As of 2023 there are many badly performing clones on the market. V2/3GHz NanoVNA uses parts like ADF4350 and AD8342 which are costly and clones have been cutting costs by using salvaged or reject parts.
See official store and look for V2 Plus4/V2 Plus4 Pro versions only to avoid getting a bad clone. We have stopped selling V2.2 versions since October 2020, so all V2 hardware that are not Plus or Plus4 are not made by us and we can not guarantee performance.
Hi,
Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB isolation. The banner spec for the pro shows 96dB dynamic range but wonder of the pro will allows tuning isolation values close to that?
Rob NZ6J
Hi,
Yes, it does a fine job. I use my pro along with the NanoVNA-QT software.
On Tue, Mar 12, 2024 at 11:03 AM Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
High isolation measurements are often more fixture limited than instrument
limited.
I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16 bit ADC.
The actual measurement SNR might be different - better, because multiple ADC
samples are averaged; worse, because a 16 bit ADC usually has 13-14 bit ENOB
(Effective number of bits) or 70-80 dB SNR. The actual measurement
performance of an ADC is affected by a bunch of things - clock noise, sampler
uncertainty, etc.
I would be challenging to verify a dynamic range like that. You’d need a
precise attenuator with 96 dB attenuation, for instance. That’s no trivial
matter.
Usually what you do is measure a few signals at various larger levels, and
then assume (verify) linearity, and extrapolate down to the noise floor.
> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J <rowlands47@gmail.com> wrote:
>
>
> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
Thanks Jim,
Very detailed response! Fixturing in this case would seem less relevant with
duplexers? They’re solidly built with n connectors. The actual attenuation in
the stop band isn’t as important as being able to accurately tune for the
null. Using the earlier model nano VNAs there was no way to reduce the
bandwidth as in the Fieldfox. The pro version seems to allow quite narrow
bandwidth. Noise is still an issue I found too, so being able to transmit the
maximum power is important. Poor stop band attenuation means desense!
Best regards,
Rob Rowlands
415 849 5667
> On Mar 12, 2024, at 9:59 PM, Jim Lux <jimlux@earthlink.net> wrote:
>
>
> High isolation measurements are often more fixture limited than instrument
limited.
>
> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16 bit ADC.
>
>
>
>
> The actual measurement SNR might be different - better, because multiple ADC
samples are averaged; worse, because a 16 bit ADC usually has 13-14 bit ENOB
(Effective number of bits) or 70-80 dB SNR. The actual measurement
performance of an ADC is affected by a bunch of things - clock noise, sampler
uncertainty, etc.
>
>
>
>
> I would be challenging to verify a dynamic range like that. You’d need a
precise attenuator with 96 dB attenuation, for instance. That’s no trivial
matter.
>
>
>
>
> Usually what you do is measure a few signals at various larger levels, and
then assume (verify) linearity, and extrapolate down to the noise floor.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
>
>
>
>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
It seems to me that your biggest concern would be with frequency accuracy.
No way to sinc the nanVNA with an external GPS disciplined time base. You
may tune the diplexer a few kHz off the desired channel.
On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
Thanks Bob,
Good advice! The best way to get around this would be to use the repeater as a
signal generator after tuning - will try that next one I do.
Do you think the v2plus pro frequency accuracy is poor? Will check the spec.
Best regards,
Rob Rowlands
415 849 5667
> On Mar 13, 2024, at 9:12 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> It seems to me that your biggest concern would be with frequency accuracy.
No way to sinc the nanVNA with an external GPS disciplined time base. You may
tune the diplexer a few kHz off the desired channel.
>
>
>
>
> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>> Thanks Jim,
>>
>>
>
>>
>> Very detailed response! Fixturing in this case would seem less relevant
with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>
>>
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>
>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>
>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16 bit ADC.
>>>
>>>
>
>>>
>>> The actual measurement SNR might be different - better, because multiple
ADC samples are averaged; worse, because a 16 bit ADC usually has 13-14 bit
ENOB (Effective number of bits) or 70-80 dB SNR. The actual measurement
performance of an ADC is affected by a bunch of things - clock noise, sampler
uncertainty, etc.
>>>
>>>
>
>>>
>>> I would be challenging to verify a dynamic range like that. You’d need a
precise attenuator with 96 dB attenuation, for instance. That’s no trivial
matter.
>>>
>>>
>
>>>
>>> Usually what you do is measure a few signals at various larger levels, and
then assume (verify) linearity, and extrapolate down to the noise floor.
>>>
>>>
>
>>>
>>>
>
>>>
>>>
>
>>>
>>>
>
>>>
>>>
>
>>>
>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>
>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
when you come in the 90 to 100 dB attenuation range then also the cables must
be of superb quality ... and an analyzer needs to be super tight shielded
between the two channels (I guess our small nanos are not good enough)
... and there may be changes in the response of the filter if temp changes..
so it maybe is better not to tune for that very deep notch at 100 plus dB but
have that notch a tiny bit wider and only 90 to 95 db
if you then use on the repeater site a transceiver that has a synced roofing
filter (some Motorola radios have that) those 90 or 95dB may be enough
dg9bfc sigi
Am 13.03.2024 17:10 schrieb Bob W0EG <morrisnc7@gmail.com>:
> It seems to me that your biggest concern would be with frequency accuracy.
No way to sinc the nanVNA with an external GPS disciplined time base. You may
tune the diplexer a few kHz off the desired channel.
>
>
>
>
> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>> Thanks Jim,
>>
>>
>
>>
>> Very detailed response! Fixturing in this case would seem less relevant
with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>
>>
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>
>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>
>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16 bit ADC.
>>>
>>>
>
>>>
>>> The actual measurement SNR might be different - better, because multiple
ADC samples are averaged; worse, because a 16 bit ADC usually has 13-14 bit
ENOB (Effective number of bits) or 70-80 dB SNR. The actual measurement
performance of an ADC is affected by a bunch of things - clock noise, sampler
uncertainty, etc.
>>>
>>>
>
>>>
>>> I would be challenging to verify a dynamic range like that. You’d need a
precise attenuator with 96 dB attenuation, for instance. That’s no trivial
matter.
>>>
>>>
>
>>>
>>> Usually what you do is measure a few signals at various larger levels, and
then assume (verify) linearity, and extrapolate down to the noise floor.
>>>
>>>
>
>>>
>>>
>
>>>
>>>
>
>>>
>>>
>
>>>
>>>
>
>>>
>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>
>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
If the tcxo is 1ppm, then at 430 MHz, the maximum error would be 430 Hz.
On the NanoVNA, 1ppm is the spec.
If one happens to have an external standard and a counter, you could measure the output of the NanoVNA and apply the appropriate corrections.
Looking at the BOM, it looks like the oscillator is a YSO680PR which is a programmable source. And it comes in three grades 20, 25, 50 ppm, so yeah, that would be a problem.
20 ppm at 400 MHz is 8 kHz,
So comparing against an external reference might be wise. you could probably do it by setting up for a sweep around 10 MHz (assuming you have a 10 MHz standard), feeding the standard (at say, 0 dBm) into the Ch1 port, and seeing where the S21 magnitude peaks. Yeah, the phase is unknown, but it's tuning the receiver through 10 MHz, and the magnitude should work.
what about replacing it with a more accurate tcxo (0.1, 0.2 or 0.5 ppm
unit)???
dg9bfc sigi
Am 14.03.2024 um 01:38 schrieb Jim Lux:
Thanks Jim, I’m also getting a pretty strong FM signal here I could use as a
standard too!
Best regards,
Rob Rowlands
415 849 5667
> On Mar 13, 2024, at 10:30 PM, Jim Lux <jimlux@earthlink.net> wrote:
>
>
>
>
> Looking at the BOM, it looks like the oscillator is a YSO680PR which is a
programmable source. And it comes in three grades 20, 25, 50 ppm, so yeah,
that would be a problem.
>
>
>
> 20 ppm at 400 MHz is 8 kHz,
>
>
>
> So comparing against an external reference might be wise. you could
probably do it by setting up for a sweep around 10 MHz (assuming you have a 10
MHz standard), feeding the standard (at say, 0 dBm) into the Ch1 port, and
seeing where the S21 magnitude peaks. Yeah, the phase is unknown, but it's
tuning the receiver through 10 MHz, and the magnitude should work.
>
>
>
>
>
>
>
Don’t know but it does not have a TCXO or an oven. Even the best equipment
drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
Hi Bob,
Here’s a very rough comparison using tinySA ultra between a NanoVNA-F V2 by
SeeSii radiating at c. 88.5MHz compared with a previously measured carrier
marker from our NPR station with no modulation. The delta of 577Hz is pretty
good for cheap kit don’t you think? I don’t have a V2 Plus 4 pro yet to test.
When I’ve time I will do the same test with my Keysight Fieldfox.
Best regards,
Rob Rowlands
415 849 5667
> On Mar 14, 2024, at 8:59 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> Don’t know but it does not have a TCXO or an oven. Even the best equipment
drifts and the the crystal ages so require re-calibration. I’ll try checking
mine with a frequency counter using a GOS reference.
>
>
>
>
> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>> Thanks Bob,
>>
>>
>
>>
>> Good advice! The best way to get around this would be to use the repeater
as a signal generator after tuning - will try that next one I do.
>>
>>
>
>>
>> Do you think the v2plus pro frequency accuracy is poor? Will check the
spec.
>>
>>
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>
>>>
>>>
>>> It seems to me that your biggest concern would be with frequency accuracy.
No way to sinc the nanVNA with an external GPS disciplined time base. You may
tune the diplexer a few kHz off the desired channel.
>>>
>>>
>
>>>
>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>
>>>> Thanks Jim,
>>>>
>>>>
>
>>>>
>>>> Very detailed response! Fixturing in this case would seem less relevant
with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>
>>>>
>
>>>>
>>>> Best regards,
>>>>
>>>> Rob Rowlands
>>>>
>>>> 415 849 5667
>>>>
>>>>
>
>>>>
>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>
>>>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>>>
>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16 bit
ADC.
>>>>>
>>>>>
>
>>>>>
>>>>> The actual measurement SNR might be different - better, because multiple
ADC samples are averaged; worse, because a 16 bit ADC usually has 13-14 bit
ENOB (Effective number of bits) or 70-80 dB SNR. The actual measurement
performance of an ADC is affected by a bunch of things - clock noise, sampler
uncertainty, etc.
>>>>>
>>>>>
>
>>>>>
>>>>> I would be challenging to verify a dynamic range like that. You’d need a
precise attenuator with 96 dB attenuation, for instance. That’s no trivial
matter.
>>>>>
>>>>>
>
>>>>>
>>>>> Usually what you do is measure a few signals at various larger levels,
and then assume (verify) linearity, and extrapolate down to the noise floor.
>>>>>
>>>>>
>
>>>>>
>>>>>
>
>>>>>
>>>>>
>
>>>>>
>>>>>
>
>>>>>
>>>>>
>
>>>>>
>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>
>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
Hi Siegfried,
Thanks, but getting better than 10ppm in a hobby device seems unrealistic and
I’m not doing surgery!
Best regards,
Rob Rowlands
415 849 5667
> On Mar 14, 2024, at 8:59 AM, Siegfried Jackstien
<siegfried.jackstien@freenet.de> wrote:
>
>
>
>
> what about replacing it with a more accurate tcxo (0.1, 0.2 or 0.5 ppm
unit)???
>
>
> dg9bfc sigi
>
>
> Am 14.03.2024 um 01:38 schrieb Jim Lux:
>
>
>> Looking at the BOM, it looks like the oscillator is a YSO680PR which is a
programmable source. And it comes in three grades 20, 25, 50 ppm, so yeah,
that would be a problem.
>>
>>
>>
>> 20 ppm at 400 MHz is 8 kHz,
>>
>>
>>
>> So comparing against an external reference might be wise. you could
probably do it by setting up for a sweep around 10 MHz (assuming you have a 10
MHz standard), feeding the standard (at say, 0 dBm) into the Ch1 port, and
seeing where the S21 magnitude peaks. Yeah, the phase is unknown, but it's
tuning the receiver through 10 MHz, and the magnitude should work.
>>
>>
>>
>>
>>
>>
>>
If it is “programmable”, is it “tweakable”? can it be calibrated against a standard? (GPSDO)
Frank
Certainly. Assuming one can find one with the right pinout.
> On Mar 14, 2024, at 8:59 AM, Siegfried Jackstien
<siegfried.jackstien@freenet.de> wrote:
>
>
>
>
> what about replacing it with a more accurate tcxo (0.1, 0.2 or 0.5 ppm
unit)???
>
>
> dg9bfc sigi
>
>
> Am 14.03.2024 um 01:38 schrieb Jim Lux:
>
>
>> Looking at the BOM, it looks like the oscillator is a YSO680PR which is a
programmable source. And it comes in three grades 20, 25, 50 ppm, so yeah,
that would be a problem.
>>
>>
>>
>> 20 ppm at 400 MHz is 8 kHz,
>>
>>
>>
>> So comparing against an external reference might be wise. you could
probably do it by setting up for a sweep around 10 MHz (assuming you have a 10
MHz standard), feeding the standard (at say, 0 dBm) into the Ch1 port, and
seeing where the S21 magnitude peaks. Yeah, the phase is unknown, but it's
tuning the receiver through 10 MHz, and the magnitude should work.
>>
>>
>>
>>
>>
>>
>>
FM signals are wide band, you need something really narrow.
> On Mar 14, 2024, at 8:59 AM, Rob Rowlands NZ6J <rowlands47@gmail.com> wrote:
>
>
> Thanks Jim, I’m also getting a pretty strong FM signal here I could use as
a standard too!
>
>
>
>
> Best regards,
>
> Rob Rowlands
>
> 415 849 5667
>
>
>
>
>> On Mar 13, 2024, at 10:30 PM, Jim Lux <jimlux@earthlink.net> wrote:
>
>
>
>>
>>
>> Looking at the BOM, it looks like the oscillator is a YSO680PR which is a
programmable source. And it comes in three grades 20, 25, 50 ppm, so yeah,
that would be a problem.
>>
>>
>>
>> 20 ppm at 400 MHz is 8 kHz,
>>
>>
>>
>> So comparing against an external reference might be wise. you could
probably do it by setting up for a sweep around 10 MHz (assuming you have a 10
MHz standard), feeding the standard (at say, 0 dBm) into the Ch1 port, and
seeing where the S21 magnitude peaks. Yeah, the phase is unknown, but it's
tuning the receiver through 10 MHz, and the magnitude should work.
>>
>>
>>
>>
>>
>>
>>
Hi Frank,
I’m not sure, but probably not going to find out! Absolute accuracy is
probably not needed in this case. If I get a chance to run it against a good
counter will post results.
Best regards,
Rob Rowlands
415 849 5667
> On Mar 14, 2024, at 9:59 PM, cocopuppy <cocopuppy@bellsouth.net> wrote:
>
>
>
>
> If it is “programmable”, is it “tweakable”? can it be calibrated against a
standard? (GPSDO)
>
> Frank
>
>
>
> **From:** NanoVNAV2@groups.io <NanoVNAV2@groups.io> **On Behalf Of**
Siegfried Jackstien
> **Sent:** Thursday, March 14, 2024 2:58 AM
> **To:** NanoVNAV2@groups.io
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro
>
>
>
> what about replacing it with a more accurate tcxo (0.1, 0.2 or 0.5 ppm
unit)???
>
> dg9bfc sigi
>
> Am 14.03.2024 um 01:38 schrieb Jim Lux:
>
>> Looking at the BOM, it looks like the oscillator is a YSO680PR which is a
programmable source. And it comes in three grades 20, 25, 50 ppm, so yeah,
that would be a problem.
>>
>>
>>
>> 20 ppm at 400 MHz is 8 kHz,
>>
>>
>>
>> So comparing against an external reference might be wise. you could
probably do it by setting up for a sweep around 10 MHz (assuming you have a 10
MHz standard), feeding the standard (at say, 0 dBm) into the Ch1 port, and
seeing where the S21 magnitude peaks. Yeah, the phase is unknown, but it's
tuning the receiver through 10 MHz, and the magnitude should work.
>>
>>
>>
>>
>>
>>
>>
Yes, good. Would the delta be 5X at 440MHz? That would be 4kHz off.
On Fri, Mar 15, 2024 at 12:58 AM Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
1ppm oscillators are a pretty standard item. That’s what’s in the NanoVNA
original.
A casual browse of digikey finds hundreds… A bit less than $2. Delivery times
on oscillators tends to be long, unless it’s a frequency that’s common.
Here’s an example
[
---
| [516](https://www.ctscorp.com/wp-content/uploads/516.pdf)[PDF Document · 889
KB](https://www.ctscorp.com/wp-content/uploads/516.pdf)
---
](https://www.ctscorp.com/wp-content/uploads/516.pdf)
> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J <rowlands47@gmail.com> wrote:
>
>
> Hi Siegfried,
>
>
>
>
> Thanks, but getting better than 10ppm in a hobby device seems unrealistic
and I’m not doing surgery!
>
>
>
>
> Best regards,
>
> Rob Rowlands
>
> 415 849 5667
>
>
>
>
>> On Mar 14, 2024, at 8:59 AM, Siegfried Jackstien
<siegfried.jackstien@freenet.de> wrote:
>
>
>
>>
>>
>> what about replacing it with a more accurate tcxo (0.1, 0.2 or 0.5 ppm
unit)???
>
>>
>> dg9bfc sigi
>
>>
>> Am 14.03.2024 um 01:38 schrieb Jim Lux:
>
>>
>>> Looking at the BOM, it looks like the oscillator is a YSO680PR which is a
programmable source. And it comes in three grades 20, 25, 50 ppm, so yeah,
that would be a problem.
>>>
>>>
>>>
>>> 20 ppm at 400 MHz is 8 kHz,
>>>
>>>
>>>
>>> So comparing against an external reference might be wise. you could
probably do it by setting up for a sweep around 10 MHz (assuming you have a 10
MHz standard), feeding the standard (at say, 0 dBm) into the Ch1 port, and
seeing where the S21 magnitude peaks. Yeah, the phase is unknown, but it's
tuning the receiver through 10 MHz, and the magnitude should work.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
In the US, FM broadcast has to be within 2000 Hz. At 100 MHz, that’s 20 ppm,
which is fairly loose. In practice, they probably are better, but no
guarantees.
Same for AM - 20 ppm.
<https://www.law.cornell.edu/cfr/text/47/73.1545>
WWV would be better (but is kind of weak unless you live in Ft. Collins or
Kauai)
> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J <rowlands47@gmail.com> wrote:
>
>
> Hi Bob,
>
>
>
>
> Here’s a very rough comparison using tinySA ultra between a NanoVNA-F V2 by
SeeSii radiating at c. 88.5MHz compared with a previously measured carrier
marker from our NPR station with no modulation. The delta of 577Hz is pretty
good for cheap kit don’t you think? I don’t have a V2 Plus 4 pro yet to test.
>
>
>
>
> <image0.jpeg>
>
>
>
>
> When I’ve time I will do the same test with my Keysight Fieldfox.
>
>
>
>
> Best regards,
>
> Rob Rowlands
>
> 415 849 5667
>
>
>
>
>> On Mar 14, 2024, at 8:59 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>>
>>
>> Don’t know but it does not have a TCXO or an oven. Even the best equipment
drifts and the the crystal ages so require re-calibration. I’ll try checking
mine with a frequency counter using a GOS reference.
>>
>>
>
>>
>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>
>>> Thanks Bob,
>>>
>>>
>
>>>
>>> Good advice! The best way to get around this would be to use the repeater
as a signal generator after tuning - will try that next one I do.
>>>
>>>
>
>>>
>>> Do you think the v2plus pro frequency accuracy is poor? Will check the
spec.
>>>
>>>
>
>>>
>>> Best regards,
>>>
>>> Rob Rowlands
>>>
>>> 415 849 5667
>>>
>>>
>
>>>
>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>
>>>>
>>>>
>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>
>>>>
>
>>>>
>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>
>>>>> Thanks Jim,
>>>>>
>>>>>
>
>>>>>
>>>>> Very detailed response! Fixturing in this case would seem less relevant
with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>
>>>>>
>
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Rob Rowlands
>>>>>
>>>>> 415 849 5667
>>>>>
>>>>>
>
>>>>>
>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>
>>>>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>>>>
>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16 bit
ADC.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> The actual measurement SNR might be different - better, because
multiple ADC samples are averaged; worse, because a 16 bit ADC usually has
13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> I would be challenging to verify a dynamic range like that. You’d need
a precise attenuator with 96 dB attenuation, for instance. That’s no trivial
matter.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> Usually what you do is measure a few signals at various larger levels,
and then assume (verify) linearity, and extrapolate down to the noise floor.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>
>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
Hi Bob,
Agreed! Let’s see how good the pro is when I get one!
Best regards,
Rob Rowlands
415 849 5667
> On Mar 15, 2024, at 8:59 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> Yes, good. Would the delta be 5X at 440MHz? That would be 4kHz off.
>
>
>
>
> On Fri, Mar 15, 2024 at 12:58 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>> Hi Bob,
>>
>>
>
>>
>> Here’s a very rough comparison using tinySA ultra between a NanoVNA-F V2 by
SeeSii radiating at c. 88.5MHz compared with a previously measured carrier
marker from our NPR station with no modulation. The delta of 577Hz is pretty
good for cheap kit don’t you think? I don’t have a V2 Plus 4 pro yet to test.
>>
>>
>
>>
>> <image0.jpeg>
>>
>>
>
>>
>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>
>>
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>
>>>
>>
>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>
>>>
>
>>>
>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>
>>>> Thanks Bob,
>>>>
>>>>
>
>>>>
>>>> Good advice! The best way to get around this would be to use the repeater
as a signal generator after tuning - will try that next one I do.
>>>>
>>>>
>
>>>>
>>>> Do you think the v2plus pro frequency accuracy is poor? Will check the
spec.
>>>>
>>>>
>
>>>>
>>>> Best regards,
>>>>
>>>> Rob Rowlands
>>>>
>>>> 415 849 5667
>>>>
>>>>
>
>>>>
>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>
>>>>>
>>>>>
>>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>>
>>>>>
>
>>>>>
>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>
>>>>>> Thanks Jim,
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> Very detailed response! Fixturing in this case would seem less
relevant with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> Best regards,
>>>>>>
>>>>>> Rob Rowlands
>>>>>>
>>>>>> 415 849 5667
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>
>>>>>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>>>>>
>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16 bit
ADC.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> The actual measurement SNR might be different - better, because
multiple ADC samples are averaged; worse, because a 16 bit ADC usually has
13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> I would be challenging to verify a dynamic range like that. You’d need
a precise attenuator with 96 dB attenuation, for instance. That’s no trivial
matter.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Usually what you do is measure a few signals at various larger levels,
and then assume (verify) linearity, and extrapolate down to the noise floor.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>
>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
>>
>>> _._,_._,_
* * *
I’m amazed that 20 ppm is acceptable! How come we don’t hear heterodynes, or
does the fm capture effect suppress them?
Best regards,
Rob Rowlands
415 849 5667
> On Mar 15, 2024, at 8:59 AM, Jim Lux <jimlux@earthlink.net> wrote:
>
>
> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz, that’s 20
ppm, which is fairly loose. In practice, they probably are better, but no
guarantees.
>
> Same for AM - 20 ppm.
>
>
>
>
> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>
>
>
>
> WWV would be better (but is kind of weak unless you live in Ft. Collins or
Kauai)
>
>
>
>
>
>
>
>
>
>
>
>
>
>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
>
>
>
>> Hi Bob,
>>
>>
>
>>
>> Here’s a very rough comparison using tinySA ultra between a NanoVNA-F V2 by
SeeSii radiating at c. 88.5MHz compared with a previously measured carrier
marker from our NPR station with no modulation. The delta of 577Hz is pretty
good for cheap kit don’t you think? I don’t have a V2 Plus 4 pro yet to test.
>>
>>
>
>>
>> <image0.jpeg>
>>
>>
>
>>
>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>
>>
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>>
>>>
>>>
>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>
>>>
>
>>>
>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>
>>>> Thanks Bob,
>>>>
>>>>
>
>>>>
>>>> Good advice! The best way to get around this would be to use the repeater
as a signal generator after tuning - will try that next one I do.
>>>>
>>>>
>
>>>>
>>>> Do you think the v2plus pro frequency accuracy is poor? Will check the
spec.
>>>>
>>>>
>
>>>>
>>>> Best regards,
>>>>
>>>> Rob Rowlands
>>>>
>>>> 415 849 5667
>>>>
>>>>
>
>>>>
>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>
>>>>>
>>>>>
>>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>>
>>>>>
>
>>>>>
>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>
>>>>>> Thanks Jim,
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> Very detailed response! Fixturing in this case would seem less
relevant with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> Best regards,
>>>>>>
>>>>>> Rob Rowlands
>>>>>>
>>>>>> 415 849 5667
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>
>>>>>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>>>>>
>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16 bit
ADC.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> The actual measurement SNR might be different - better, because
multiple ADC samples are averaged; worse, because a 16 bit ADC usually has
13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> I would be challenging to verify a dynamic range like that. You’d need
a precise attenuator with 96 dB attenuation, for instance. That’s no trivial
matter.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Usually what you do is measure a few signals at various larger levels,
and then assume (verify) linearity, and extrapolate down to the noise floor.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>
>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
I have a good counter (OCXO) and a GPSDO . I’m going to see how well my VNA2 Plus and Tiny SA look
Thanks’
It’s a ratio. So yes.
But as noted, broadcast stations can be 20 ppm off.
What’s the accuracy of the TinySA?
Realistically, if you’re going to be tuning things to a gnat’s eyelash,
frequency wise, it’s worth it to get a frequency standard of some sort. Good
10 MHz OCXOs show up surplus all the time in the $50-100 range. And you can
get a good 1pps from a variety of inexpensive $10-20 GPS modules - typical raw
performance is 20-100 ns/second (so 0.02 to 0.1 ppm) on a single shot
measurement - much better if you average. In a GPS disciplined oscillator, or
just a counter using the 1pps on your 10 MHz, you can do substantially better
by averaging over time.
Comparing against WWV is good to a few Hz.
But be careful. Once you have one decent time/frequency source, you’ll be
tempted to get more, to improve it, just a little bit. And first thing you
know, you’re making deals for hydrogen masers and cesium clocks from sketchy
sources - my precious.
> On Mar 15, 2024, at 8:59 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> Yes, good. Would the delta be 5X at 440MHz? That would be 4kHz off.
>
>
>
>
> On Fri, Mar 15, 2024 at 12:58 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>> Hi Bob,
>>
>>
>
>>
>> Here’s a very rough comparison using tinySA ultra between a NanoVNA-F V2 by
SeeSii radiating at c. 88.5MHz compared with a previously measured carrier
marker from our NPR station with no modulation. The delta of 577Hz is pretty
good for cheap kit don’t you think? I don’t have a V2 Plus 4 pro yet to test.
>>
>>
>
>>
>> <image0.jpeg>
>>
>>
>
>>
>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>
>>
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>
>>>
>>
>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>
>>>
>
>>>
>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>
>>>> Thanks Bob,
>>>>
>>>>
>
>>>>
>>>> Good advice! The best way to get around this would be to use the repeater
as a signal generator after tuning - will try that next one I do.
>>>>
>>>>
>
>>>>
>>>> Do you think the v2plus pro frequency accuracy is poor? Will check the
spec.
>>>>
>>>>
>
>>>>
>>>> Best regards,
>>>>
>>>> Rob Rowlands
>>>>
>>>> 415 849 5667
>>>>
>>>>
>
>>>>
>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>
>>>>>
>>>>>
>>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>>
>>>>>
>
>>>>>
>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>
>>>>>> Thanks Jim,
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> Very detailed response! Fixturing in this case would seem less
relevant with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> Best regards,
>>>>>>
>>>>>> Rob Rowlands
>>>>>>
>>>>>> 415 849 5667
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>
>>>>>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>>>>>
>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16 bit
ADC.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> The actual measurement SNR might be different - better, because
multiple ADC samples are averaged; worse, because a 16 bit ADC usually has
13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> I would be challenging to verify a dynamic range like that. You’d need
a precise attenuator with 96 dB attenuation, for instance. That’s no trivial
matter.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Usually what you do is measure a few signals at various larger levels,
and then assume (verify) linearity, and extrapolate down to the noise floor.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>
>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
>>
>>> _._,_._,_
* * *
If you are tuning 440 MHz cavities there is no case where you need more
than 5 kHz accuracy. The cavity notches will move around far more than
that with normal temperature changes. That is why we traditionally used
such a wide split on 440 MHz.
50ppm is far more than enough resolution or stability.
A tuning a cavity isn't anything remotely like netting a local
oscillator to center a 10kHz crystal filter or a discriminator! The pass
tuning will be extremely wide and the notch won't be all that narrow and
rigid in frequency.
In the 1970s we used regular radios, attenuator pads, and drifty old
vacuum tube signal generators.
On 3/14/2024 1:24 PM, Rob Rowlands NZ6J wrote:
FM has 100 kHz deviation, so the center frequency isn’t very critical (the
detector is insensitive to it). And licensing makes sure that nobody else on
your channel is anywhere close to near your power, so yeah, capture effect.
On AM you could get heterodynes, but just as with FM, your license protects
you from anyone close by. Aircraft use AM, and heterodynes are a feature of
life.
Broadcast doesn’t use SSB (in general), which is where frequency accuracy
would be important, for “no need to use clarifier” on speech. 20Hz (1ppm at 20
MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be intolerable.
There are “simulbroadcast” on the same frequency in EU for TV (and maybe FM),
all transmitting the same signal, and for that, the frequency control has to
be much better.
> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
>
>
> I’m amazed that 20 ppm is acceptable! How come we don’t hear heterodynes,
or does the fm capture effect suppress them?
>
>
>
>
> Best regards,
>
> Rob Rowlands
>
> 415 849 5667
>
>
>
>
>> On Mar 15, 2024, at 8:59 AM, Jim Lux <jimlux@earthlink.net> wrote:
>
>
>
>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz, that’s 20
ppm, which is fairly loose. In practice, they probably are better, but no
guarantees.
>>
>> Same for AM - 20 ppm.
>>
>>
>
>>
>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>
>>
>
>>
>> WWV would be better (but is kind of weak unless you live in Ft. Collins or
Kauai)
>>
>>
>
>>
>>
>
>>
>>
>
>>
>>
>
>>
>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
>
>
>>
>>> Hi Bob,
>>>
>>>
>
>>>
>>> Here’s a very rough comparison using tinySA ultra between a NanoVNA-F V2
by SeeSii radiating at c. 88.5MHz compared with a previously measured carrier
marker from our NPR station with no modulation. The delta of 577Hz is pretty
good for cheap kit don’t you think? I don’t have a V2 Plus 4 pro yet to test.
>>>
>>>
>
>>>
>>> <image0.jpeg>
>>>
>>>
>
>>>
>>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>>
>>>
>
>>>
>>> Best regards,
>>>
>>> Rob Rowlands
>>>
>>> 415 849 5667
>>>
>>>
>
>>>
>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>>>
>>>>
>>>>
>>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>>
>>>>
>
>>>>
>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>
>>>>> Thanks Bob,
>>>>>
>>>>>
>
>>>>>
>>>>> Good advice! The best way to get around this would be to use the
repeater as a signal generator after tuning - will try that next one I do.
>>>>>
>>>>>
>
>>>>>
>>>>> Do you think the v2plus pro frequency accuracy is poor? Will check the
spec.
>>>>>
>>>>>
>
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Rob Rowlands
>>>>>
>>>>> 415 849 5667
>>>>>
>>>>>
>
>>>>>
>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>
>>>>>>
>>>>>>
>>>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>
>>>>>>> Thanks Jim,
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Very detailed response! Fixturing in this case would seem less
relevant with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Best regards,
>>>>>>>
>>>>>>> Rob Rowlands
>>>>>>>
>>>>>>> 415 849 5667
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>
>>>>>>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>>>>>>
>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16 bit
ADC.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> The actual measurement SNR might be different - better, because
multiple ADC samples are averaged; worse, because a 16 bit ADC usually has
13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> I would be challenging to verify a dynamic range like that. You’d
need a precise attenuator with 96 dB attenuation, for instance. That’s no
trivial matter.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> Usually what you do is measure a few signals at various larger
levels, and then assume (verify) linearity, and extrapolate down to the noise
floor.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>
>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
I thought the OP was tuning duplexes for amateur radio repeaters. Ham FM
uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
On Sat, Mar 16, 2024 at 12:58 AM Jim Lux <jimlux@earthlink.net> wrote:
FM broadcast.. much wider deviation, and subcarriers too. So 20 ppm frequency
tolerance is just fine.
> On Mar 16, 2024, at 9:30 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
>
>
>
> I thought the OP was tuning duplexes for amateur radio repeaters. Ham FM
uses 25 kHz channel spacing, most public service now uses 12.5 kHz spacing.
NBFM deviation is narrower as is most digital (like P25 or DMR).
>
>
>
>
> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>> FM has 100 kHz deviation, so the center frequency isn’t very critical (the
detector is insensitive to it). And licensing makes sure that nobody else on
your channel is anywhere close to near your power, so yeah, capture effect.
>>
>>
>
>>
>> On AM you could get heterodynes, but just as with FM, your license protects
you from anyone close by. Aircraft use AM, and heterodynes are a feature of
life.
>>
>>
>
>>
>> Broadcast doesn’t use SSB (in general), which is where frequency accuracy
would be important, for “no need to use clarifier” on speech. 20Hz (1ppm at 20
MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be intolerable.
>>
>>
>
>>
>> There are “simulbroadcast” on the same frequency in EU for TV (and maybe
FM), all transmitting the same signal, and for that, the frequency control has
to be much better.
>>
>>
>
>>
>>
>
>>
>>
>
>>
>>
>
>>
>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>
>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear heterodynes,
or does the fm capture effect suppress them?
>>
>>>
>
>>>
>>> Best regards,
>>>
>>> Rob Rowlands
>>>
>>> 415 849 5667
>>>
>>>
>
>>>
>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>
>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz, that’s 20
ppm, which is fairly loose. In practice, they probably are better, but no
guarantees.
>>>>
>>>> Same for AM - 20 ppm.
>>>>
>>>>
>
>>>>
>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>
>>>>
>
>>>>
>>>> WWV would be better (but is kind of weak unless you live in Ft. Collins
or Kauai)
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>
>>>>> Hi Bob,
>>>>>
>>>>>
>
>>>>>
>>>>> Here’s a very rough comparison using tinySA ultra between a NanoVNA-F V2
by SeeSii radiating at c. 88.5MHz compared with a previously measured carrier
marker from our NPR station with no modulation. The delta of 577Hz is pretty
good for cheap kit don’t you think? I don’t have a V2 Plus 4 pro yet to test.
>>>>>
>>>>>
>
>>>>>
>>>>> <image0.jpeg>
>>>>>
>>>>>
>
>>>>>
>>>>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>>>>
>>>>>
>
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Rob Rowlands
>>>>>
>>>>> 415 849 5667
>>>>>
>>>>>
>
>>>>>
>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>
>>>>>>
>>>>>>
>>>>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>
>>>>>>> Thanks Bob,
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Good advice! The best way to get around this would be to use the
repeater as a signal generator after tuning - will try that next one I do.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will check the
spec.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Best regards,
>>>>>>>
>>>>>>> Rob Rowlands
>>>>>>>
>>>>>>> 415 849 5667
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>
>>>>>>>>> Thanks Jim,
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Very detailed response! Fixturing in this case would seem less
relevant with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>>
>>>>>>>>> Rob Rowlands
>>>>>>>>>
>>>>>>>>> 415 849 5667
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>>
>>>>>>>>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>>>>>>>>
>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16
bit ADC.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> The actual measurement SNR might be different - better, because
multiple ADC samples are averaged; worse, because a 16 bit ADC usually has
13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> I would be challenging to verify a dynamic range like that. You’d
need a precise attenuator with 96 dB attenuation, for instance. That’s no
trivial matter.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> Usually what you do is measure a few signals at various larger
levels, and then assume (verify) linearity, and extrapolate down to the noise
floor.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>>
>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
>>
>>> _._,_._,_
* * *
I am confused. Why do you need a diplexer for FM broadcast transmission?
Coupling two transmitters on different channels to a single antenna? I
usually associate diplexers with repeaters.
On Sun, Mar 17, 2024 at 2:28 AM Jim Lux <jimlux@earthlink.net> wrote:
I’m tuning duplexers for ham 440 repeaters
Best regards,
Rob Rowlands
415 849 5667
> On Mar 17, 2024, at 11:28 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> I am confused. Why do you need a diplexer for FM broadcast transmission?
Coupling two transmitters on different channels to a single antenna? I
usually associate diplexers with repeaters.
>
>
>
>
> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>> FM broadcast.. much wider deviation, and subcarriers too. So 20 ppm
frequency tolerance is just fine.
>>
>>
>
>>
>>
>
>>
>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>
>>>
>>
>>>
>
>>>
>>> I thought the OP was tuning duplexes for amateur radio repeaters. Ham FM
uses 25 kHz channel spacing, most public service now uses 12.5 kHz spacing.
NBFM deviation is narrower as is most digital (like P25 or DMR).
>>>
>>>
>
>>>
>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>
>>>> FM has 100 kHz deviation, so the center frequency isn’t very critical
(the detector is insensitive to it). And licensing makes sure that nobody else
on your channel is anywhere close to near your power, so yeah, capture effect.
>>>>
>>>>
>
>>>>
>>>> On AM you could get heterodynes, but just as with FM, your license
protects you from anyone close by. Aircraft use AM, and heterodynes are a
feature of life.
>>>>
>>>>
>
>>>>
>>>> Broadcast doesn’t use SSB (in general), which is where frequency accuracy
would be important, for “no need to use clarifier” on speech. 20Hz (1ppm at 20
MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be intolerable.
>>>>
>>>>
>
>>>>
>>>> There are “simulbroadcast” on the same frequency in EU for TV (and maybe
FM), all transmitting the same signal, and for that, the frequency control has
to be much better.
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>
>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them?
>>>>
>>>>>
>
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Rob Rowlands
>>>>>
>>>>> 415 849 5667
>>>>>
>>>>>
>
>>>>>
>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>
>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz, that’s
20 ppm, which is fairly loose. In practice, they probably are better, but no
guarantees.
>>>>>>
>>>>>> Same for AM - 20 ppm.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> WWV would be better (but is kind of weak unless you live in Ft. Collins
or Kauai)
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>
>>>>>>> Hi Bob,
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Here’s a very rough comparison using tinySA ultra between a NanoVNA-F
V2 by SeeSii radiating at c. 88.5MHz compared with a previously measured
carrier marker from our NPR station with no modulation. The delta of 577Hz is
pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4 pro yet to
test.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> <image0.jpeg>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Best regards,
>>>>>>>
>>>>>>> Rob Rowlands
>>>>>>>
>>>>>>> 415 849 5667
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>
>>>>>>>>> Thanks Bob,
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Good advice! The best way to get around this would be to use the
repeater as a signal generator after tuning - will try that next one I do.
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will check
the spec.
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>>
>>>>>>>>> Rob Rowlands
>>>>>>>>>
>>>>>>>>> 415 849 5667
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>
>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Very detailed response! Fixturing in this case would seem less
relevant with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Best regards,
>>>>>>>>>>>
>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>
>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>>>>
>>>>>>>>>>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>>>>>>>>>>
>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16
bit ADC.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> The actual measurement SNR might be different - better, because
multiple ADC samples are averaged; worse, because a 16 bit ADC usually has
13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> I would be challenging to verify a dynamic range like that. You’d
need a precise attenuator with 96 dB attenuation, for instance. That’s no
trivial matter.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> Usually what you do is measure a few signals at various larger
levels, and then assume (verify) linearity, and extrapolate down to the noise
floor.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>>>>
>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
>>>>
>>>>> > _._,_._,_
* * *
I think it has to do with freq stability and deviation (not the modulation) of the duplexer when calibrating it. It 20ppm “deviation” is good enough for broadcast, it should be OK for amateur use
Does that help?
Frank
He said duplexers which I assume are hi-Q cavity type.
The six-can commercial duplexers in my 440MHz repeater are about 1.5 MHz
wide pass at 3dB down. The notches barely change depth over about 1 MHz BW.
73 Tom
They are On 3/17/2024 1:05 PM, Bob W0EG wrote:
> I am confused. Why do you need a diplexer for FM broadcast
> transmission? Coupling two transmitters on different channels to a
> single antenna? I usually associate diplexers with repeaters.
>
> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux <jimlux@earthlink.net> wrote:
>
> FM broadcast.. much wider deviation, and subcarriers too. So 20
> ppm frequency tolerance is just fine.
>
>
>> On Mar 16, 2024, at 9:30 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>>
>>
>>
>> I thought the OP was tuning duplexes for amateur radio
>> repeaters. Ham FM uses 25 kHz channel spacing, most public
>> service now uses 12.5 kHz spacing. NBFM deviation is narrower as
>> is most digital (like P25 or DMR).
>>
>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux <jimlux@earthlink.net>
>> wrote:
>>
>> FM has 100 kHz deviation, so the center frequency isn’t very
>> critical (the detector is insensitive to it). And licensing
>> makes sure that nobody else on your channel is anywhere close
>> to near your power, so yeah, capture effect.
>>
>> On AM you could get heterodynes, but just as with FM, your
>> license protects you from anyone close by. Aircraft use AM,
>> and heterodynes are a feature of life.
>>
>> Broadcast doesn’t use SSB (in general), which is where
>> frequency accuracy would be important, for “no need to use
>> clarifier” on speech. 20Hz (1ppm at 20 MHz) is good enough
>> for that. 20 ppm (400 Hz at 20 MHz) would be intolerable.
>>
>> There are “simulbroadcast” on the same frequency in EU for TV
>> (and maybe FM), all transmitting the same signal, and for
>> that, the frequency control has to be much better.
>>
>>
>>
>>
>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
>>> <rowlands47@gmail.com> wrote:
>>>
>>> I’m amazed that 20 ppm is acceptable! How come we don’t
>>> hear heterodynes, or does the fm capture effect suppress them?
>>>
>>> Best regards,
>>> Rob Rowlands
>>> 415 849 5667
>>>
>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux <jimlux@earthlink.net>
>>>> wrote:
>>>>
>>>> In the US, FM broadcast has to be within 2000 Hz. At 100
>>>> MHz, that’s 20 ppm, which is fairly loose. In practice,
>>>> they probably are better, but no guarantees.
>>>> Same for AM - 20 ppm.
>>>>
>>>> https://www.law.cornell.edu/cfr/text/47/73.1545
>>>>
>>>> WWV would be better (but is kind of weak unless you live in
>>>> Ft. Collins or Kauai)
>>>>
>>>>
>>>>
>>>>
>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
>>>>> <rowlands47@gmail.com> wrote:
>>>>>
>>>>> Hi Bob,
>>>>>
>>>>> Here’s a very rough comparison using tinySA ultra between
>>>>> a NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared
>>>>> with a previously measured carrier marker from our NPR
>>>>> station with no modulation. The delta of 577Hz is pretty
>>>>> good for cheap kit don’t you think? I don’t have a V2 Plus
>>>>> 4 pro yet to test.
>>>>>
>>>>> <image0.jpeg>
>>>>>
>>>>> When I’ve time I will do the same test with my Keysight
>>>>> Fieldfox.
>>>>>
>>>>> Best regards,
>>>>> Rob Rowlands
>>>>> 415 849 5667
>>>>>
>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
>>>>>> <morrisnc7@gmail.com> wrote:
>>>>>>
>>>>>>
>>>>>> Don’t know but it does not have a TCXO or an oven. Even
>>>>>> the best equipment drifts and the the crystal ages so
>>>>>> require re-calibration. I’ll try checking mine with a
>>>>>> frequency counter using a GOS reference.
>>>>>>
>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>
>>>>>> Thanks Bob,
>>>>>>
>>>>>> Good advice! The best way to get around this would be
>>>>>> to use the repeater as a signal generator after
>>>>>> tuning - will try that next one I do.
>>>>>>
>>>>>> Do you think the v2plus pro frequency accuracy is
>>>>>> poor? Will check the spec.
>>>>>>
>>>>>> Best regards,
>>>>>> Rob Rowlands
>>>>>> 415 849 5667
>>>>>>
>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
>>>>>>> <morrisnc7@gmail.com> wrote:
>>>>>>>
>>>>>>>
>>>>>>> It seems to me that your biggest concern would be
>>>>>>> with frequency accuracy. No way to sinc the nanVNA
>>>>>>> with an external GPS disciplined time base. You may
>>>>>>> tune the diplexer a few kHz off the desired channel.
>>>>>>>
>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
>>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>>
>>>>>>> Thanks Jim,
>>>>>>>
>>>>>>> Very detailed response! Fixturing in this case
>>>>>>> would seem less relevant with duplexers? They’re
>>>>>>> solidly built with n connectors. The actual
>>>>>>> attenuation in the stop band isn’t as important
>>>>>>> as being able to accurately tune for the null.
>>>>>>> Using the earlier model nano VNAs there was no
>>>>>>> way to reduce the bandwidth as in the Fieldfox.
>>>>>>> The pro version seems to allow quite narrow
>>>>>>> bandwidth. Noise is still an issue I found too,
>>>>>>> so being able to transmit the maximum power is
>>>>>>> important. Poor stop band attenuation means desense!
>>>>>>>
>>>>>>> Best regards,
>>>>>>> Rob Rowlands
>>>>>>> 415 849 5667
>>>>>>>
>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
>>>>>>>> <jimlux@earthlink.net> wrote:
>>>>>>>>
>>>>>>>> High isolation measurements are often more
>>>>>>>> fixture limited than instrument limited.
>>>>>>>> I suspect, though, that the 96 dB happens to be
>>>>>>>> 6 dB/bit for a 16 bit ADC.
>>>>>>>>
>>>>>>>> The actual measurement SNR might be different -
>>>>>>>> better, because multiple ADC samples are
>>>>>>>> averaged; worse, because a 16 bit ADC usually
>>>>>>>> has 13-14 bit ENOB (Effective number of bits)
>>>>>>>> or 70-80 dB SNR. The actual measurement
>>>>>>>> performance of an ADC is affected by a bunch of
>>>>>>>> things - clock noise, sampler uncertainty, etc.
>>>>>>>>
>>>>>>>> I would be challenging to verify a dynamic
>>>>>>>> range like that. You’d need a precise
>>>>>>>> attenuator with 96 dB attenuation, for
>>>>>>>> instance. That’s no trivial matter.
>>>>>>>>
>>>>>>>> Usually what you do is measure a few signals at
>>>>>>>> various larger levels, and then assume (verify)
>>>>>>>> linearity, and extrapolate down to the noise
>>>>>>>> floor.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
>>>>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> Ive been tuning 440 duplexers with a Keysight
>>>>>>>>> Fieldfox to about 80dB isolation. The banner
>>>>>>>>> spec for the pro shows 96dB dynamic range but
>>>>>>>>> wonder of the pro will allows tuning isolation
>>>>>>>>> values close to that?
>>>>>>>>>
>>>>>>>>> Rob NZ6J
>>>>>>>
>
--
This email has been checked for viruses by AVG antivirus software.
www.avg.com
Greetings Bob,
A newbie to the group but been in commercial FM . Two run two transmitters into a Tee, dumps as much energy into the opposing transmitter. As a result, BOTH transmitters will make harmonic variations. One being TX1 + TX2, and assorted other band splattering excitement. PLUS TX1 - TX2 and more bad stuff.
Then just for fun, TX2 + TX1 and you get the idea..
So some would say a second antenna for TX2. Now you still have to filter the antennas. One way is filter cans BPBR or space between.
Hope this helps.
Newbie Kevin
>From my iPhone
It’s not..
It’s related to using a broadcast station as a frequency reference, so you can
calibrate the frequency accuracy of your NanoVNA.
The upshot is that broadcast stations are only required to be within 20 ppm,
so they make a crummy reference if you need 1ppm accuracy to tune a narrowband
diplexer - at 440 MHz, 1 ppm is 440 Hz. 20 ppm is 8.8 kHz, which is a
substantial fraction of the channel spacing/bandwidth for a narrow band FM
repeater.
> On Mar 17, 2024, at 11:28 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> I am confused. Why do you need a diplexer for FM broadcast transmission?
Coupling two transmitters on different channels to a single antenna? I
usually associate diplexers with repeaters.
>
>
>
>
> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>> FM broadcast.. much wider deviation, and subcarriers too. So 20 ppm
frequency tolerance is just fine.
>>
>>
>
>>
>>
>
>>
>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>
>>>
>>
>>>
>
>>>
>>> I thought the OP was tuning duplexes for amateur radio repeaters. Ham FM
uses 25 kHz channel spacing, most public service now uses 12.5 kHz spacing.
NBFM deviation is narrower as is most digital (like P25 or DMR).
>>>
>>>
>
>>>
>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>
>>>> FM has 100 kHz deviation, so the center frequency isn’t very critical
(the detector is insensitive to it). And licensing makes sure that nobody else
on your channel is anywhere close to near your power, so yeah, capture effect.
>>>>
>>>>
>
>>>>
>>>> On AM you could get heterodynes, but just as with FM, your license
protects you from anyone close by. Aircraft use AM, and heterodynes are a
feature of life.
>>>>
>>>>
>
>>>>
>>>> Broadcast doesn’t use SSB (in general), which is where frequency accuracy
would be important, for “no need to use clarifier” on speech. 20Hz (1ppm at 20
MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be intolerable.
>>>>
>>>>
>
>>>>
>>>> There are “simulbroadcast” on the same frequency in EU for TV (and maybe
FM), all transmitting the same signal, and for that, the frequency control has
to be much better.
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>
>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them?
>>>>
>>>>>
>
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Rob Rowlands
>>>>>
>>>>> 415 849 5667
>>>>>
>>>>>
>
>>>>>
>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>
>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz, that’s
20 ppm, which is fairly loose. In practice, they probably are better, but no
guarantees.
>>>>>>
>>>>>> Same for AM - 20 ppm.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> WWV would be better (but is kind of weak unless you live in Ft. Collins
or Kauai)
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>
>>>>>>> Hi Bob,
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Here’s a very rough comparison using tinySA ultra between a NanoVNA-F
V2 by SeeSii radiating at c. 88.5MHz compared with a previously measured
carrier marker from our NPR station with no modulation. The delta of 577Hz is
pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4 pro yet to
test.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> <image0.jpeg>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Best regards,
>>>>>>>
>>>>>>> Rob Rowlands
>>>>>>>
>>>>>>> 415 849 5667
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>
>>>>>>>>> Thanks Bob,
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Good advice! The best way to get around this would be to use the
repeater as a signal generator after tuning - will try that next one I do.
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will check
the spec.
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>>
>>>>>>>>> Rob Rowlands
>>>>>>>>>
>>>>>>>>> 415 849 5667
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>
>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Very detailed response! Fixturing in this case would seem less
relevant with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Best regards,
>>>>>>>>>>>
>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>
>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>>>>
>>>>>>>>>>>> High isolation measurements are often more fixture limited than
instrument limited.
>>>>>>>>>>>>
>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a 16
bit ADC.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> The actual measurement SNR might be different - better, because
multiple ADC samples are averaged; worse, because a 16 bit ADC usually has
13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> I would be challenging to verify a dynamic range like that. You’d
need a precise attenuator with 96 dB attenuation, for instance. That’s no
trivial matter.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> Usually what you do is measure a few signals at various larger
levels, and then assume (verify) linearity, and extrapolate down to the noise
floor.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>>>>
>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
>>>>
>>>>> > _._,_._,_
* * *
Less tower wind load.
One antenna.
One feedline.
Glenn
On 3/17/2024 1:05 PM, Bob W0EG wrote:
> I am confused. Why do you need a diplexer for FM broadcast
> transmission? Coupling two transmitters on different channels to a
> single antenna? I usually associate diplexers with repeaters.
>
> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux <jimlux@earthlink.net> wrote:
>
> FM broadcast.. much wider deviation, and subcarriers too. So 20
> ppm frequency tolerance is just fine.
>
>
>> On Mar 16nn, 2024, at 9:30 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>>
>>
>>
>> I thought the OP was tuning duplexes for amateur radio
>> repeaters. Ham FM uses 25 kHz channel spacing, most public
>> service now uses 12.5 kHz spacing. NBFM deviation is narrower as
>> is most digital (like P25 or DMR).
>>
>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux <jimlux@earthlink.net>
>> wrote:
>>
>> FM has 100 kHz deviation, so the center frequency isn’t very
>> critical (the detector is insensitive to it). And licensing
>> makes sure that nobody else on your channel is anywhere close
>> to near your power, so yeah, capture effect.
>>
>> On AM you could get heterodynes, but just as with FM, your
>> license protects you from anyone close by. Aircraft use AM,
>> and heterodynes are a feature of life.
>>
>> Broadcast doesn’t use SSB (in general), which is where
>> frequency accuracy would be important, for “no need to use
>> clarifier” on speech. 20Hz (1ppm at 20 MHz) is good enough
>> for that. 20 ppm (400 Hz at 20 MHz) would be intolerable.
>>
>> There are “simulbroadcast” on the same frequency in EU for TV
>> (and maybe FM), all transmitting the same signal, and for
>> that, the frequency control has to be much better.
>>
>>
>>
>>
>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
>>> <rowlands47@gmail.com> wrote:
>>>
>>> I’m amazed that 20 ppm is acceptable! How come we don’t
>>> hear heterodynes, or does the fm capture effect suppress them?
>>>
>>> Best regards,
>>> Rob Rowlands
>>> 415 849 5667
>>>
>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux <jimlux@earthlink.net>
>>>> wrote:
>>>>
>>>> In the US, FM broadcast has to be within 2000 Hz. At 100
>>>> MHz, that’s 20 ppm, which is fairly loose. In practice,
>>>> they probably are better, but no guarantees.
>>>> Same for AM - 20 ppm.
>>>>
>>>> https://www.law.cornell.edu/cfr/text/47/73.1545
>>>>
>>>> WWV would be better (but is kind of weak unless you live in
>>>> Ft. Collins or Kauai)
>>>>
>>>>
>>>>
>>>>
>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
>>>>> <rowlands47@gmail.com> wrote:
>>>>>
>>>>> Hi Bob,
>>>>>
>>>>> Here’s a very rough comparison using tinySA ultra between
>>>>> a NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared
>>>>> with a previously measured carrier marker from our NPR
>>>>> station with no modulation. The delta of 577Hz is pretty
>>>>> good for cheap kit don’t you think? I don’t have a V2 Plus
>>>>> 4 pro yet to test.
>>>>>
>>>>> <image0.jpeg>
>>>>>
>>>>> When I’ve time I will do the same test with my Keysight
>>>>> Fieldfox.
>>>>>
>>>>> Best regards,
>>>>> Rob Rowlands
>>>>> 415 849 5667
>>>>>
>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
>>>>>> <morrisnc7@gmail.com> wrote:
>>>>>>
>>>>>>
>>>>>> Don’t know but it does not have a TCXO or an oven. Even
>>>>>> the best equipment drifts and the the crystal ages so
>>>>>> require re-calibration. I’ll try checking mine with a
>>>>>> frequency counter using a GOS reference.
>>>>>>
>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>
>>>>>> Thanks Bob,
>>>>>>
>>>>>> Good advice! The best way to get around this would be
>>>>>> to use the repeater as a signal generator after
>>>>>> tuning - will try that next one I do.
>>>>>>
>>>>>> Do you think the v2plus pro frequency accuracy is
>>>>>> poor? Will check the spec.
>>>>>>
>>>>>> Best regards,
>>>>>> Rob Rowlands
>>>>>> 415 849 5667
>>>>>>
>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
>>>>>>> <morrisnc7@gmail.com> wrote:
>>>>>>>
>>>>>>>
>>>>>>> It seems to me that your biggest concern would be
>>>>>>> with frequency accuracy. No way to sinc the nanVNA
>>>>>>> with an external GPS disciplined time base. You may
>>>>>>> tune the diplexer a few kHz off the desired channel.
>>>>>>>
>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
>>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>>
>>>>>>> Thanks Jim,
>>>>>>>
>>>>>>> Very detailed response! Fixturing in this case
>>>>>>> would seem less relevant with duplexers? They’re
>>>>>>> solidly built with n connectors. The actual
>>>>>>> attenuation in the stop band isn’t as important
>>>>>>> as being able to accurately tune for the null.
>>>>>>> Using the earlier model nano VNAs there was no
>>>>>>> way to reduce the bandwidth as in the Fieldfox.
>>>>>>> The pro version seems to allow quite narrow
>>>>>>> bandwidth. Noise is still an issue I found too,
>>>>>>> so being able to transmit the maximum power is
>>>>>>> important. Poor stop band attenuation means desense!
>>>>>>>
>>>>>>> Best regards,
>>>>>>> Rob Rowlands
>>>>>>> 415 849 5667
>>>>>>>
>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
>>>>>>>> <jimlux@earthlink.net> wrote:
>>>>>>>>
>>>>>>>> High isolation measurements are often more
>>>>>>>> fixture limited than instrument limited.
>>>>>>>> I suspect, though, that the 96 dB happens to be
>>>>>>>> 6 dB/bit for a 16 bit ADC.
>>>>>>>>
>>>>>>>> The actual measurement SNR might be different -
>>>>>>>> better, because multiple ADC samples are
>>>>>>>> averaged; worse, because a 16 bit ADC usually
>>>>>>>> has 13-14 bit ENOB (Effective number of bits)
>>>>>>>> or 70-80 dB SNR. The actual measurement
>>>>>>>> performance of an ADC is affected by a bunch of
>>>>>>>> things - clock noise, sampler uncertainty, etc.
>>>>>>>>
>>>>>>>> I would be challenging to verify a dynamic
>>>>>>>> range like that. You’d need a precise
>>>>>>>> attenuator with 96 dB attenuation, for
>>>>>>>> instance. That’s no trivial matter.
>>>>>>>>
>>>>>>>> Usually what you do is measure a few signals at
>>>>>>>> various larger levels, and then assume (verify)
>>>>>>>> linearity, and extrapolate down to the noise
>>>>>>>> floor.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
>>>>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> Ive been tuning 440 duplexers with a Keysight
>>>>>>>>> Fieldfox to about 80dB isolation. The banner
>>>>>>>>> spec for the pro shows 96dB dynamic range but
>>>>>>>>> wonder of the pro will allows tuning isolation
>>>>>>>>> values close to that?
>>>>>>>>>
>>>>>>>>> Rob NZ6J
>>>>>>>
>
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIVwb4uiv@arrl.net AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
The Keysight Fieldfox has a PC program that will adjust the TCXO to match a
connected 10MHz reference. I will check my nanoVNA with a frequency
counter connected to a GPS reference.
On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
Hi Bob,
That’d be great. I don’t have access to a disciplined counter. What you think
about using the NOAA weather radios on 162 MHz as ersatz standards? They must
be synchronized as their coverages overlap, and I’ve not heard heterodynes?
Additionally they have short periods of silence when the carrier can be used
to calibrate our cheap RF stuff?
Best regards,
Rob Rowlands
415 849 5667
> On Mar 18, 2024, at 8:29 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> The Keysight Fieldfox has a PC program that will adjust the TCXO to match a
connected 10MHz reference. I will check my nanoVNA with a frequency counter
connected to a GPS reference.
>
>
>
>
> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>> I’m tuning duplexers for ham 440 repeaters
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>
>>>
>>
>>> I am confused. Why do you need a diplexer for FM broadcast transmission?
Coupling two transmitters on different channels to a single antenna? I
usually associate diplexers with repeaters.
>>>
>>>
>
>>>
>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>
>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20 ppm
frequency tolerance is just fine.
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>
>>>>>
>>>>
>>>>>
>
>>>>>
>>>>> I thought the OP was tuning duplexes for amateur radio repeaters. Ham
FM uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
>>>>>
>>>>>
>
>>>>>
>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>>>
>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very critical
(the detector is insensitive to it). And licensing makes sure that nobody else
on your channel is anywhere close to near your power, so yeah, capture effect.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> On AM you could get heterodynes, but just as with FM, your license
protects you from anyone close by. Aircraft use AM, and heterodynes are a
feature of life.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> Broadcast doesn’t use SSB (in general), which is where frequency
accuracy would be important, for “no need to use clarifier” on speech. 20Hz
(1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be
intolerable.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> There are “simulbroadcast” on the same frequency in EU for TV (and
maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>
>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them?
>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Best regards,
>>>>>>>
>>>>>>> Rob Rowlands
>>>>>>>
>>>>>>> 415 849 5667
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>
>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz, that’s
20 ppm, which is fairly loose. In practice, they probably are better, but no
guarantees.
>>>>>>>>
>>>>>>>> Same for AM - 20 ppm.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> WWV would be better (but is kind of weak unless you live in Ft.
Collins or Kauai)
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>
>>>>>>>>> Hi Bob,
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test.
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> <image0.jpeg>
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>>
>>>>>>>>> Rob Rowlands
>>>>>>>>>
>>>>>>>>> 415 849 5667
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>
>>>>>>>>>>> Thanks Bob,
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Good advice! The best way to get around this would be to use the
repeater as a signal generator after tuning - will try that next one I do.
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will check
the spec.
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Best regards,
>>>>>>>>>>>
>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>
>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>>>
>>>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Very detailed response! Fixturing in this case would seem less
relevant with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>
>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>
>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> High isolation measurements are often more fixture limited
than instrument limited.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a
16 bit ADC.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> The actual measurement SNR might be different - better, because
multiple ADC samples are averaged; worse, because a 16 bit ADC usually has
13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like that.
You’d need a precise attenuator with 96 dB attenuation, for instance. That’s
no trivial matter.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Usually what you do is measure a few signals at various larger
levels, and then assume (verify) linearity, and extrapolate down to the noise
floor.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
>>>>>>
>>>>>>> > > _._,_._,_
* * *
That kind of thing is why the FieldFox costs what it does.
It could be added to PC software pretty easily, not sure it would fit in the
firmware in the NanoVNA2 itself.
But while it’s just a few lines of code to implement, it does have a
“maintenance tail”
> On Mar 18, 2024, at 8:29 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> The Keysight Fieldfox has a PC program that will adjust the TCXO to match a
connected 10MHz reference. I will check my nanoVNA with a frequency counter
connected to a GPS reference.
>
>
>
>
> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>> I’m tuning duplexers for ham 440 repeaters
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>
>>>
>>
>>> I am confused. Why do you need a diplexer for FM broadcast transmission?
Coupling two transmitters on different channels to a single antenna? I
usually associate diplexers with repeaters.
>>>
>>>
>
>>>
>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>
>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20 ppm
frequency tolerance is just fine.
>>>>
>>>>
>
>>>>
>>>>
>
>>>>
>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>
>>>>>
>>>>
>>>>>
>
>>>>>
>>>>> I thought the OP was tuning duplexes for amateur radio repeaters. Ham
FM uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
>>>>>
>>>>>
>
>>>>>
>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>>>
>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very critical
(the detector is insensitive to it). And licensing makes sure that nobody else
on your channel is anywhere close to near your power, so yeah, capture effect.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> On AM you could get heterodynes, but just as with FM, your license
protects you from anyone close by. Aircraft use AM, and heterodynes are a
feature of life.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> Broadcast doesn’t use SSB (in general), which is where frequency
accuracy would be important, for “no need to use clarifier” on speech. 20Hz
(1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be
intolerable.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> There are “simulbroadcast” on the same frequency in EU for TV (and
maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>
>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them?
>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Best regards,
>>>>>>>
>>>>>>> Rob Rowlands
>>>>>>>
>>>>>>> 415 849 5667
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>
>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz, that’s
20 ppm, which is fairly loose. In practice, they probably are better, but no
guarantees.
>>>>>>>>
>>>>>>>> Same for AM - 20 ppm.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> WWV would be better (but is kind of weak unless you live in Ft.
Collins or Kauai)
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>
>>>>>>>>> Hi Bob,
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test.
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> <image0.jpeg>
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>>
>>>>>>>>> Rob Rowlands
>>>>>>>>>
>>>>>>>>> 415 849 5667
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>
>>>>>>>>>>> Thanks Bob,
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Good advice! The best way to get around this would be to use the
repeater as a signal generator after tuning - will try that next one I do.
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will check
the spec.
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Best regards,
>>>>>>>>>>>
>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>
>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>>>
>>>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Very detailed response! Fixturing in this case would seem less
relevant with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>
>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>
>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> High isolation measurements are often more fixture limited
than instrument limited.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a
16 bit ADC.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> The actual measurement SNR might be different - better, because
multiple ADC samples are averaged; worse, because a 16 bit ADC usually has
13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like that.
You’d need a precise attenuator with 96 dB attenuation, for instance. That’s
no trivial matter.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Usually what you do is measure a few signals at various larger
levels, and then assume (verify) linearity, and extrapolate down to the noise
floor.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
>>>>>>
>>>>>>> > > _._,_._,_
* * *
NOAA Weather radio is FM, so you’d not hear heterodynes. They’re probably 20
ppm. If there’s two on the same frequency, the FM capture effect gets the
stronger one.
WWV or WWVH are 1ppm (as received with ionospheric variations).
> On Mar 18, 2024, at 9:59 PM, Rob Rowlands NZ6J <rowlands47@gmail.com> wrote:
>
>
>
>
>
>
> Hi Bob,
>
>
>
>
> That’d be great. I don’t have access to a disciplined counter. What you
think about using the NOAA weather radios on 162 MHz as ersatz standards? They
must be synchronized as their coverages overlap, and I’ve not heard
heterodynes? Additionally they have short periods of silence when the carrier
can be used to calibrate our cheap RF stuff?
>
>
>
>
> Best regards,
>
> Rob Rowlands
>
> 415 849 5667
>
>
>
>
>> On Mar 18, 2024, at 8:29 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>>
>>
>> The Keysight Fieldfox has a PC program that will adjust the TCXO to match a
connected 10MHz reference. I will check my nanoVNA with a frequency counter
connected to a GPS reference.
>>
>>
>
>>
>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>
>>> I’m tuning duplexers for ham 440 repeaters
>
>>>
>>> Best regards,
>>>
>>> Rob Rowlands
>>>
>>> 415 849 5667
>>>
>>>
>
>>>
>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>
>>>>
>>>
>>>> I am confused. Why do you need a diplexer for FM broadcast transmission?
Coupling two transmitters on different channels to a single antenna? I
usually associate diplexers with repeaters.
>>>>
>>>>
>
>>>>
>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>>
>>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20 ppm
frequency tolerance is just fine.
>>>>>
>>>>>
>
>>>>>
>>>>>
>
>>>>>
>>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>
>>>>>>
>>>>>
>>>>>>
>
>>>>>>
>>>>>> I thought the OP was tuning duplexes for amateur radio repeaters. Ham
FM uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>>>>
>>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very critical
(the detector is insensitive to it). And licensing makes sure that nobody else
on your channel is anywhere close to near your power, so yeah, capture effect.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> On AM you could get heterodynes, but just as with FM, your license
protects you from anyone close by. Aircraft use AM, and heterodynes are a
feature of life.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> Broadcast doesn’t use SSB (in general), which is where frequency
accuracy would be important, for “no need to use clarifier” on speech. 20Hz
(1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be
intolerable.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> There are “simulbroadcast” on the same frequency in EU for TV (and
maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better.
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>
>>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them?
>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>>
>>>>>>>> Rob Rowlands
>>>>>>>>
>>>>>>>> 415 849 5667
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>
>>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz,
that’s 20 ppm, which is fairly loose. In practice, they probably are better,
but no guarantees.
>>>>>>>>>
>>>>>>>>> Same for AM - 20 ppm.
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> WWV would be better (but is kind of weak unless you live in Ft.
Collins or Kauai)
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>
>>>>>>>>>> Hi Bob,
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> <image0.jpeg>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> Best regards,
>>>>>>>>>>
>>>>>>>>>> Rob Rowlands
>>>>>>>>>>
>>>>>>>>>> 415 849 5667
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>>
>>>>>>>>>>>> Thanks Bob,
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> Good advice! The best way to get around this would be to use the
repeater as a signal generator after tuning - will try that next one I do.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will
check the spec.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>
>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>
>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> It seems to me that your biggest concern would be with frequency
accuracy. No way to sinc the nanVNA with an external GPS disciplined time
base. You may tune the diplexer a few kHz off the desired channel.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Very detailed response! Fixturing in this case would seem less
relevant with duplexers? They’re solidly built with n connectors. The actual
attenuation in the stop band isn’t as important as being able to accurately
tune for the null. Using the earlier model nano VNAs there was no way to
reduce the bandwidth as in the Fieldfox. The pro version seems to allow quite
narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> High isolation measurements are often more fixture limited
than instrument limited.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for a
16 bit ADC.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> The actual measurement SNR might be different - better,
because multiple ADC samples are averaged; worse, because a 16 bit ADC usually
has 13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like that.
You’d need a precise attenuator with 96 dB attenuation, for instance. That’s
no trivial matter.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Usually what you do is measure a few signals at various larger
levels, and then assume (verify) linearity, and extrapolate down to the noise
floor.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
>>>>>>>
>>>>>>>> > > _._,_._,_
* * *
NanoVNA set to CW 440 MHz. Off by over 500kHz
On Tue, Mar 19, 2024 at 12:59 AM Jim Lux <jimlux@earthlink.net> wrote:
The weather stations are not synchronized.
Each is its own transmitter, the only connection to the transmitter is
audio, antenna and power.
Glenn
On 3/18/2024 12:10 PM, Rob Rowlands NZ6J wrote:
>
> Hi Bob,
>
> That’d be great. I don’t have access to a disciplined counter. What
> you think about using the NOAA weather radios on 162 MHz as ersatz
> standards? They must be synchronized as their coverages overlap, and
> I’ve not heard heterodynes? Additionally they have short periods of
> silence when the carrier can be used to calibrate our cheap RF stuff?
>
> Best regards,
> Rob Rowlands
> 415 849 5667
>
>> On Mar 18, 2024, at 8:29 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>>
>>
>> The Keysight Fieldfox has a PC program that will adjust the TCXO to
>> match a connected 10MHz reference. I will check my nanoVNA with a
>> frequency counter connected to a GPS reference.
>>
>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
>> <rowlands47@gmail.com> wrote:
>>
>> I’m tuning duplexers for ham 440 repeaters
>> Best regards,
>> Rob Rowlands
>> 415 849 5667
>>
>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>>>
>>>
>>> I am confused. Why do you need a diplexer for FM broadcast
>>> transmission? Coupling two transmitters on different channels
>>> to a single antenna? I usually associate diplexers with repeaters.
>>>
>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux <jimlux@earthlink.net>
>>> wrote:
>>>
>>> FM broadcast.. much wider deviation, and subcarriers too.
>>> So 20 ppm frequency tolerance is just fine.
>>>
>>>
>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG <morrisnc7@gmail.com>
>>>> wrote:
>>>>
>>>>
>>>>
>>>> I thought the OP was tuning duplexes for amateur radio
>>>> repeaters. Ham FM uses 25 kHz channel spacing, most public
>>>> service now uses 12.5 kHz spacing. NBFM deviation is
>>>> narrower as is most digital (like P25 or DMR).
>>>>
>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
>>>> <jimlux@earthlink.net> wrote:
>>>>
>>>> FM has 100 kHz deviation, so the center frequency isn’t
>>>> very critical (the detector is insensitive to it). And
>>>> licensing makes sure that nobody else on your channel
>>>> is anywhere close to near your power, so yeah, capture
>>>> effect.
>>>>
>>>> On AM you could get heterodynes, but just as with FM,
>>>> your license protects you from anyone close by.
>>>> Aircraft use AM, and heterodynes are a feature of life.
>>>>
>>>> Broadcast doesn’t use SSB (in general), which is where
>>>> frequency accuracy would be important, for “no need to
>>>> use clarifier” on speech. 20Hz (1ppm at 20 MHz) is good
>>>> enough for that. 20 ppm (400 Hz at 20 MHz) would be
>>>> intolerable.
>>>>
>>>> There are “simulbroadcast” on the same frequency in EU
>>>> for TV (and maybe FM), all transmitting the same
>>>> signal, and for that, the frequency control has to be
>>>> much better.
>>>>
>>>>
>>>>
>>>>
>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
>>>>> <rowlands47@gmail.com> wrote:
>>>>>
>>>>> I’m amazed that 20 ppm is acceptable! How come we
>>>>> don’t hear heterodynes, or does the fm capture effect
>>>>> suppress them?
>>>>>
>>>>> Best regards,
>>>>> Rob Rowlands
>>>>> 415 849 5667
>>>>>
>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
>>>>>> <jimlux@earthlink.net> wrote:
>>>>>>
>>>>>> In the US, FM broadcast has to be within 2000 Hz. At
>>>>>> 100 MHz, that’s 20 ppm, which is fairly loose. In
>>>>>> practice, they probably are better, but no guarantees.
>>>>>> Same for AM - 20 ppm.
>>>>>>
>>>>>> https://www.law.cornell.edu/cfr/text/47/73.1545
>>>>>>
>>>>>> WWV would be better (but is kind of weak unless you
>>>>>> live in Ft. Collins or Kauai)
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
>>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>>
>>>>>>> Hi Bob,
>>>>>>>
>>>>>>> Here’s a very rough comparison using tinySA ultra
>>>>>>> between a NanoVNA-F V2 by SeeSii radiating at c.
>>>>>>> 88.5MHz compared with a previously measured carrier
>>>>>>> marker from our NPR station with no modulation. The
>>>>>>> delta of 577Hz is pretty good for cheap kit don’t
>>>>>>> you think? I don’t have a V2 Plus 4 pro yet to test.
>>>>>>>
>>>>>>> <image0.jpeg>
>>>>>>>
>>>>>>> When I’ve time I will do the same test with my
>>>>>>> Keysight Fieldfox.
>>>>>>>
>>>>>>> Best regards,
>>>>>>> Rob Rowlands
>>>>>>> 415 849 5667
>>>>>>>
>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
>>>>>>>> <morrisnc7@gmail.com> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> Don’t know but it does not have a TCXO or an oven.
>>>>>>>> Even the best equipment drifts and the the crystal
>>>>>>>> ages so require re-calibration. I’ll try checking
>>>>>>>> mine with a frequency counter using a GOS reference.
>>>>>>>>
>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
>>>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>>>
>>>>>>>> Thanks Bob,
>>>>>>>>
>>>>>>>> Good advice! The best way to get around this
>>>>>>>> would be to use the repeater as a signal
>>>>>>>> generator after tuning - will try that next one
>>>>>>>> I do.
>>>>>>>>
>>>>>>>> Do you think the v2plus pro frequency accuracy
>>>>>>>> is poor? Will check the spec.
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>> Rob Rowlands
>>>>>>>> 415 849 5667
>>>>>>>>
>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
>>>>>>>>> <morrisnc7@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> It seems to me that your biggest concern would
>>>>>>>>> be with frequency accuracy. No way to
>>>>>>>>> sinc the nanVNA with an external GPS
>>>>>>>>> disciplined time base. You may tune the
>>>>>>>>> diplexer a few kHz off the desired channel.
>>>>>>>>>
>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands
>>>>>>>>> NZ6J <rowlands47@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>> Thanks Jim,
>>>>>>>>>
>>>>>>>>> Very detailed response! Fixturing in this
>>>>>>>>> case would seem less relevant with
>>>>>>>>> duplexers? They’re solidly built with n
>>>>>>>>> connectors. The actual attenuation in the
>>>>>>>>> stop band isn’t as important as being able
>>>>>>>>> to accurately tune for the null. Using the
>>>>>>>>> earlier model nano VNAs there was no way
>>>>>>>>> to reduce the bandwidth as in the
>>>>>>>>> Fieldfox. The pro version seems to allow
>>>>>>>>> quite narrow bandwidth. Noise is still an
>>>>>>>>> issue I found too, so being able to
>>>>>>>>> transmit the maximum power is important.
>>>>>>>>> Poor stop band attenuation means desense!
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>> Rob Rowlands
>>>>>>>>> 415 849 5667
>>>>>>>>>
>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
>>>>>>>>>> <jimlux@earthlink.net> wrote:
>>>>>>>>>>
>>>>>>>>>> High isolation measurements are often
>>>>>>>>>> more fixture limited than instrument
>>>>>>>>>> limited.
>>>>>>>>>> I suspect, though, that the 96 dB happens
>>>>>>>>>> to be 6 dB/bit for a 16 bit ADC.
>>>>>>>>>>
>>>>>>>>>> The actual measurement SNR might be
>>>>>>>>>> different - better, because multiple ADC
>>>>>>>>>> samples are averaged; worse, because a 16
>>>>>>>>>> bit ADC usually has 13-14 bit ENOB
>>>>>>>>>> (Effective number of bits) or 70-80 dB
>>>>>>>>>> SNR. The actual measurement performance
>>>>>>>>>> of an ADC is affected by a bunch of
>>>>>>>>>> things - clock noise, sampler
>>>>>>>>>> uncertainty, etc.
>>>>>>>>>>
>>>>>>>>>> I would be challenging to verify a
>>>>>>>>>> dynamic range like that. You’d need a
>>>>>>>>>> precise attenuator with 96 dB
>>>>>>>>>> attenuation, for instance. That’s no
>>>>>>>>>> trivial matter.
>>>>>>>>>>
>>>>>>>>>> Usually what you do is measure a few
>>>>>>>>>> signals at various larger levels, and
>>>>>>>>>> then assume (verify) linearity, and
>>>>>>>>>> extrapolate down to the noise floor.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob
>>>>>>>>>>> Rowlands NZ6J <rowlands47@gmail.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> Ive been tuning 440 duplexers with a
>>>>>>>>>>> Keysight Fieldfox to about 80dB
>>>>>>>>>>> isolation. The banner spec for the pro
>>>>>>>>>>> shows 96dB dynamic range but wonder of
>>>>>>>>>>> the pro will allows tuning isolation
>>>>>>>>>>> values close to that?
>>>>>>>>>>>
>>>>>>>>>>> Rob NZ6J
>>>>>>>>>
>
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIVwb4uiv@arrl.net AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
On Tue, Mar 19, 2024 at 10:11 AM Bob Morris <morrisnc7@gmail.com> wrote:
I should note that the “CW” output from the nano is not a pure sine wave,
more of a rounded off square wave. So it is possible that the counter may
have issues with the signal. I try to have a look at it on a spectrum
analyzer also synced to the 10MHz reference. Also, when measuring a
10MHz signal on this counter, removing the GPS reference only changed the
reading by twenty five Hz.
On Tue, Mar 19, 2024 at 11:14 AM Bob Morris <morrisnc7@gmail.com> wrote:
Thanks Glenn,
How come we don’t hear heterodynes, perhaps I need to listen on AM?
Best regards,
Rob Rowlands
415 849 5667
> On Mar 19, 2024, at 9:29 AM, Glenn Little <glennmaillist@bellsouth.net>
wrote:
>
>
> The weather stations are not synchronized.
> Each is its own transmitter, the only connection to the transmitter is
audio, antenna and power.
>
> Glenn
>
>
>
> On 3/18/2024 12:10 PM, Rob Rowlands NZ6J wrote:
>
>
>>
>>
>> Hi Bob,
>>
>>
>
>>
>> That’d be great. I don’t have access to a disciplined counter. What you
think about using the NOAA weather radios on 162 MHz as ersatz standards? They
must be synchronized as their coverages overlap, and I’ve not heard
heterodynes? Additionally they have short periods of silence when the carrier
can be used to calibrate our cheap RF stuff?
>>
>>
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 18, 2024, at 8:29 AM, Bob W0EG
[<morrisnc7@gmail.com>](mailto:morrisnc7@gmail.com) wrote:
>
>
>>
>>>
>>>
>>> The Keysight Fieldfox has a PC program that will adjust the TCXO to match
a connected 10MHz reference. I will check my nanoVNA with a frequency counter
connected to a GPS reference.
>>>
>>>
>
>>>
>>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>
>>>> I’m tuning duplexers for ham 440 repeaters
>
>>>>
>>>> Best regards,
>>>>
>>>> Rob Rowlands
>>>>
>>>> 415 849 5667
>>>>
>>>>
>
>>>>
>>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>
>>>>>
>>>>
>>>>> I am confused. Why do you need a diplexer for FM broadcast
transmission? Coupling two transmitters on different channels to a single
antenna? I usually associate diplexers with repeaters.
>>>>>
>>>>>
>
>>>>>
>>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>>>
>>>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20 ppm
frequency tolerance is just fine.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>
>>>>>>>
>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> I thought the OP was tuning duplexes for amateur radio repeaters. Ham
FM uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>>>>>
>>>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very critical
(the detector is insensitive to it). And licensing makes sure that nobody else
on your channel is anywhere close to near your power, so yeah, capture effect.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> On AM you could get heterodynes, but just as with FM, your license
protects you from anyone close by. Aircraft use AM, and heterodynes are a
feature of life.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> Broadcast doesn’t use SSB (in general), which is where frequency
accuracy would be important, for “no need to use clarifier” on speech. 20Hz
(1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be
intolerable.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> There are “simulbroadcast” on the same frequency in EU for TV (and
maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>
>>>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them?
>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>>
>>>>>>>>> Rob Rowlands
>>>>>>>>>
>>>>>>>>> 415 849 5667
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>>
>>>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz,
that’s 20 ppm, which is fairly loose. In practice, they probably are better,
but no guarantees.
>>>>>>>>>>
>>>>>>>>>> Same for AM - 20 ppm.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> WWV would be better (but is kind of weak unless you live in Ft.
Collins or Kauai)
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>>
>>>>>>>>>>> Hi Bob,
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test.
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> <image0.jpeg>
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Best regards,
>>>>>>>>>>>
>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>
>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>>>
>>>>>>>>>>>>> Thanks Bob,
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Good advice! The best way to get around this would be to use the
repeater as a signal generator after tuning - will try that next one I do.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will
check the spec.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>
>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>
>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> It seems to me that your biggest concern would be with
frequency accuracy. No way to sinc the nanVNA with an external GPS
disciplined time base. You may tune the diplexer a few kHz off the desired
channel.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Very detailed response! Fixturing in this case would seem
less relevant with duplexers? They’re solidly built with n connectors. The
actual attenuation in the stop band isn’t as important as being able to
accurately tune for the null. Using the earlier model nano VNAs there was no
way to reduce the bandwidth as in the Fieldfox. The pro version seems to allow
quite narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> High isolation measurements are often more fixture limited
than instrument limited.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for
a 16 bit ADC.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> The actual measurement SNR might be different - better,
because multiple ADC samples are averaged; worse, because a 16 bit ADC usually
has 13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like that.
You’d need a precise attenuator with 96 dB attenuation, for instance. That’s
no trivial matter.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Usually what you do is measure a few signals at various
larger levels, and then assume (verify) linearity, and extrapolate down to
the noise floor.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
>
>
>
>
>
> --
> -----------------------------------------------------------------------
> Glenn Little ARRL Technical Specialist QCWA LM 28417
> Amateur Callsign: WB4UIV
[wb4uiv@arrl.net](mailto:wb4uiv@arrl.net) AMSAT LM 2178
> QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
> "It is not the class of license that the Amateur holds but the class
> of the Amateur that holds the license"
_._,_._,_
* * *
Hi Bob,
I just tested the 440MHz CW output of my NanoVNA-H4 with the Fieldfox sync’d to GPS.
Attached is the FF Spectrum Analyzer plot with markers showing the Nano output at 439.99924MHz. This would be 760Hz low, or 1.73ppm if my math is correct. Not bad don’t you think? I used to work with stratum 3 telecom clocks at 4.6ppm!
I also looked at the frequency delta between the FieldFox internal clock and GPS, and only saw about 100Hz. I would have expected your HP 5385 counter to be better as it probably has an oven?
Just for giggles I have ordered this OCXO from Amazon that should be interesting – for $20 it might be useful. https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8 <https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1> &psc=1 Also ordered a $60 GPS disciplined source from Ali express https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu <https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa> &gatewayAdapt=glo2usa
Keeping time here..
73,
Rob NZ6J
415 849 5667
I am not sure how you would use external signals into the VNA as the VNA is
not a spectrum analyzer. The receivers are broadband and assume that they
are seeing stimulation from the VNA’s output.
On Tue, Mar 19, 2024 at 12:29 PM Jim Lux <jimlux@earthlink.net> wrote:
FM makes heterodyne beat notes almost the same as AM, except signal
levels have to be closer. Part of our 2M net training is teaching users
to recognize a background beat note or squeal usually means someone
weaker is doubling with the stronger station.
On 3/19/2024 9:30 AM, Jim Lux wrote:
> NOAA Weather radio is FM, so you’d not hear heterodynes. They’re
> probably 20 ppm. If there’s two on the same frequency, the FM capture
> effect gets the stronger one.
>
> WWV or WWVH are 1ppm (as received with ionospheric variations).
>
>
>> On Mar 18, 2024, at 9:59 PM, Rob Rowlands NZ6J <rowlands47@gmail.com>
>> wrote:
>>
>>
>>
>> Hi Bob,
>>
>> That’d be great. I don’t have access to a disciplined counter. What
>> you think about using the NOAA weather radios on 162 MHz as ersatz
>> standards? They must be synchronized as their coverages overlap, and
>> I’ve not heard heterodynes? Additionally they have short periods of
>> silence when the carrier can be used to calibrate our cheap RF stuff?
>>
>> Best regards,
>> Rob Rowlands
>> 415 849 5667
>>
>>> On Mar 18, 2024, at 8:29 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>>>
>>>
>>> The Keysight Fieldfox has a PC program that will adjust the TCXO to
>>> match a connected 10MHz reference. I will check my nanoVNA with a
>>> frequency counter connected to a GPS reference.
>>>
>>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
>>> <rowlands47@gmail.com> wrote:
>>>
>>> I’m tuning duplexers for ham 440 repeaters
>>> Best regards,
>>> Rob Rowlands
>>> 415 849 5667
>>>
>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>>>>
>>>>
>>>> I am confused. Why do you need a diplexer for FM broadcast
>>>> transmission? Coupling two transmitters on different channels
>>>> to a single antenna? I usually associate diplexers with
>>>> repeaters.
>>>>
>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux <jimlux@earthlink.net>
>>>> wrote:
>>>>
>>>> FM broadcast.. much wider deviation, and subcarriers too.
>>>> So 20 ppm frequency tolerance is just fine.
>>>>
>>>>
>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
>>>>> <morrisnc7@gmail.com> wrote:
>>>>>
>>>>>
>>>>>
>>>>> I thought the OP was tuning duplexes for amateur radio
>>>>> repeaters. Ham FM uses 25 kHz channel spacing, most
>>>>> public service now uses 12.5 kHz spacing. NBFM deviation
>>>>> is narrower as is most digital (like P25 or DMR).
>>>>>
>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
>>>>> <jimlux@earthlink.net> wrote:
>>>>>
>>>>> FM has 100 kHz deviation, so the center frequency
>>>>> isn’t very critical (the detector is insensitive to
>>>>> it). And licensing makes sure that nobody else on your
>>>>> channel is anywhere close to near your power, so yeah,
>>>>> capture effect.
>>>>>
>>>>> On AM you could get heterodynes, but just as with FM,
>>>>> your license protects you from anyone close by.
>>>>> Aircraft use AM, and heterodynes are a feature of life.
>>>>>
>>>>> Broadcast doesn’t use SSB (in general), which is where
>>>>> frequency accuracy would be important, for “no need to
>>>>> use clarifier” on speech. 20Hz (1ppm at 20 MHz) is
>>>>> good enough for that. 20 ppm (400 Hz at 20 MHz) would
>>>>> be intolerable.
>>>>>
>>>>> There are “simulbroadcast” on the same frequency in EU
>>>>> for TV (and maybe FM), all transmitting the same
>>>>> signal, and for that, the frequency control has to be
>>>>> much better.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>
>>>>>> I’m amazed that 20 ppm is acceptable! How come we
>>>>>> don’t hear heterodynes, or does the fm capture effect
>>>>>> suppress them?
>>>>>>
>>>>>> Best regards,
>>>>>> Rob Rowlands
>>>>>> 415 849 5667
>>>>>>
>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
>>>>>>> <jimlux@earthlink.net> wrote:
>>>>>>>
>>>>>>> In the US, FM broadcast has to be within 2000 Hz.
>>>>>>> At 100 MHz, that’s 20 ppm, which is fairly loose. In
>>>>>>> practice, they probably are better, but no guarantees.
>>>>>>> Same for AM - 20 ppm.
>>>>>>>
>>>>>>> https://www.law.cornell.edu/cfr/text/47/73.1545
>>>>>>>
>>>>>>> WWV would be better (but is kind of weak unless you
>>>>>>> live in Ft. Collins or Kauai)
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
>>>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>>>
>>>>>>>> Hi Bob,
>>>>>>>>
>>>>>>>> Here’s a very rough comparison using tinySA ultra
>>>>>>>> between a NanoVNA-F V2 by SeeSii radiating at c.
>>>>>>>> 88.5MHz compared with a previously measured carrier
>>>>>>>> marker from our NPR station with no modulation. The
>>>>>>>> delta of 577Hz is pretty good for cheap kit don’t
>>>>>>>> you think? I don’t have a V2 Plus 4 pro yet to test.
>>>>>>>>
>>>>>>>> <image0.jpeg>
>>>>>>>>
>>>>>>>> When I’ve time I will do the same test with my
>>>>>>>> Keysight Fieldfox.
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>> Rob Rowlands
>>>>>>>> 415 849 5667
>>>>>>>>
>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
>>>>>>>>> <morrisnc7@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Don’t know but it does not have a TCXO or an
>>>>>>>>> oven. Even the best equipment drifts and the the
>>>>>>>>> crystal ages so require re-calibration. I’ll try
>>>>>>>>> checking mine with a frequency counter using a GOS
>>>>>>>>> reference.
>>>>>>>>>
>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
>>>>>>>>> <rowlands47@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>> Thanks Bob,
>>>>>>>>>
>>>>>>>>> Good advice! The best way to get around this
>>>>>>>>> would be to use the repeater as a signal
>>>>>>>>> generator after tuning - will try that next
>>>>>>>>> one I do.
>>>>>>>>>
>>>>>>>>> Do you think the v2plus pro frequency accuracy
>>>>>>>>> is poor? Will check the spec.
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>> Rob Rowlands
>>>>>>>>> 415 849 5667
>>>>>>>>>
>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
>>>>>>>>>> <morrisnc7@gmail.com> wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> It seems to me that your biggest concern
>>>>>>>>>> would be with frequency accuracy. No way to
>>>>>>>>>> sinc the nanVNA with an external GPS
>>>>>>>>>> disciplined time base. You may tune the
>>>>>>>>>> diplexer a few kHz off the desired channel.
>>>>>>>>>>
>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands
>>>>>>>>>> NZ6J <rowlands47@gmail.com> wrote:
>>>>>>>>>>
>>>>>>>>>> Thanks Jim,
>>>>>>>>>>
>>>>>>>>>> Very detailed response! Fixturing in this
>>>>>>>>>> case would seem less relevant with
>>>>>>>>>> duplexers? They’re solidly built with n
>>>>>>>>>> connectors. The actual attenuation in the
>>>>>>>>>> stop band isn’t as important as being
>>>>>>>>>> able to accurately tune for the null.
>>>>>>>>>> Using the earlier model nano VNAs there
>>>>>>>>>> was no way to reduce the bandwidth as in
>>>>>>>>>> the Fieldfox. The pro version seems to
>>>>>>>>>> allow quite narrow bandwidth. Noise is
>>>>>>>>>> still an issue I found too, so being able
>>>>>>>>>> to transmit the maximum power is
>>>>>>>>>> important. Poor stop band attenuation
>>>>>>>>>> means desense!
>>>>>>>>>>
>>>>>>>>>> Best regards,
>>>>>>>>>> Rob Rowlands
>>>>>>>>>> 415 849 5667
>>>>>>>>>>
>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
>>>>>>>>>>> <jimlux@earthlink.net> wrote:
>>>>>>>>>>>
>>>>>>>>>>> High isolation measurements are often
>>>>>>>>>>> more fixture limited than instrument
>>>>>>>>>>> limited.
>>>>>>>>>>> I suspect, though, that the 96 dB
>>>>>>>>>>> happens to be 6 dB/bit for a 16 bit ADC.
>>>>>>>>>>>
>>>>>>>>>>> The actual measurement SNR might be
>>>>>>>>>>> different - better, because multiple ADC
>>>>>>>>>>> samples are averaged; worse, because a
>>>>>>>>>>> 16 bit ADC usually has 13-14 bit ENOB
>>>>>>>>>>> (Effective number of bits) or 70-80 dB
>>>>>>>>>>> SNR. The actual measurement performance
>>>>>>>>>>> of an ADC is affected by a bunch of
>>>>>>>>>>> things - clock noise, sampler
>>>>>>>>>>> uncertainty, etc.
>>>>>>>>>>>
>>>>>>>>>>> I would be challenging to verify a
>>>>>>>>>>> dynamic range like that. You’d need a
>>>>>>>>>>> precise attenuator with 96 dB
>>>>>>>>>>> attenuation, for instance. That’s no
>>>>>>>>>>> trivial matter.
>>>>>>>>>>>
>>>>>>>>>>> Usually what you do is measure a few
>>>>>>>>>>> signals at various larger levels, and
>>>>>>>>>>> then assume (verify) linearity, and
>>>>>>>>>>> extrapolate down to the noise floor.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob
>>>>>>>>>>>> Rowlands NZ6J <rowlands47@gmail.com> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> Hi,
>>>>>>>>>>>>
>>>>>>>>>>>> Ive been tuning 440 duplexers with a
>>>>>>>>>>>> Keysight Fieldfox to about 80dB
>>>>>>>>>>>> isolation. The banner spec for the pro
>>>>>>>>>>>> shows 96dB dynamic range but wonder of
>>>>>>>>>>>> the pro will allows tuning isolation
>>>>>>>>>>>> values close to that?
>>>>>>>>>>>>
>>>>>>>>>>>> Rob NZ6J
>>>>>>>>>>
>
--
This email has been checked for viruses by AVG antivirus software.
www.avg.com
That looks really good. Perhaps my counter has difficulty with the nest
square wave output. I’ll try looking at it with a spectrum analyzer and an
oscilloscope.
On Wed, Mar 20, 2024 at 6:00 AM Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
I’d be looking to replace the crystal or oscillator. That’s WAY beyond the
typical 20 ppm for crummy crystals or the 1ppm for a decent TCXO.
(The original NanoVNA has a 1ppm TCXO, don’t know what the other ones use)
> On Mar 19, 2024, at 9:29 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> <IMG_5039.jpeg>
>
> NanoVNA set to CW 440 MHz. Off by over 500kHz
>
>
>
>
> On Tue, Mar 19, 2024 at 12:59 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>> That kind of thing is why the FieldFox costs what it does.
>>
>> It could be added to PC software pretty easily, not sure it would fit in
the firmware in the NanoVNA2 itself.
>>
>> But while it’s just a few lines of code to implement, it does have a
“maintenance tail”
>>
>>
>
>>
>>
>
>>
>>> On Mar 18, 2024, at 8:29 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>
>>>
>>
>>> The Keysight Fieldfox has a PC program that will adjust the TCXO to match
a connected 10MHz reference. I will check my nanoVNA with a frequency counter
connected to a GPS reference.
>>>
>>>
>
>>>
>>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>
>>>> I’m tuning duplexers for ham 440 repeaters
>
>>>>
>>>> Best regards,
>>>>
>>>> Rob Rowlands
>>>>
>>>> 415 849 5667
>>>>
>>>>
>
>>>>
>>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>
>>>>>
>>>>
>>>>> I am confused. Why do you need a diplexer for FM broadcast
transmission? Coupling two transmitters on different channels to a single
antenna? I usually associate diplexers with repeaters.
>>>>>
>>>>>
>
>>>>>
>>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>>>
>>>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20 ppm
frequency tolerance is just fine.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>
>
>>>>>>
>>>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>
>>>>>>>
>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> I thought the OP was tuning duplexes for amateur radio repeaters. Ham
FM uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
>>>>>>>
>>>>>>>
>
>>>>>>>
>>>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>>>>>>>
>>>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very critical
(the detector is insensitive to it). And licensing makes sure that nobody else
on your channel is anywhere close to near your power, so yeah, capture effect.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> On AM you could get heterodynes, but just as with FM, your license
protects you from anyone close by. Aircraft use AM, and heterodynes are a
feature of life.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> Broadcast doesn’t use SSB (in general), which is where frequency
accuracy would be important, for “no need to use clarifier” on speech. 20Hz
(1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be
intolerable.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>> There are “simulbroadcast” on the same frequency in EU for TV (and
maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better.
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>
>
>>>>>>>>
>>>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>
>>>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them?
>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>>
>>>>>>>>> Rob Rowlands
>>>>>>>>>
>>>>>>>>> 415 849 5667
>>>>>>>>>
>>>>>>>>>
>
>>>>>>>>>
>>>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>>
>>>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz,
that’s 20 ppm, which is fairly loose. In practice, they probably are better,
but no guarantees.
>>>>>>>>>>
>>>>>>>>>> Same for AM - 20 ppm.
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>> WWV would be better (but is kind of weak unless you live in Ft.
Collins or Kauai)
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>
>
>>>>>>>>>>
>>>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>>
>>>>>>>>>>> Hi Bob,
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test.
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> <image0.jpeg>
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> When I’ve time I will do the same test with my Keysight Fieldfox.
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>> Best regards,
>>>>>>>>>>>
>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>
>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>
>>>>>>>>>>>
>
>>>>>>>>>>>
>>>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the best
equipment drifts and the the crystal ages so require re-calibration. I’ll try
checking mine with a frequency counter using a GOS reference.
>>>>>>>>>>>>
>>>>>>>>>>>>
>
>>>>>>>>>>>>
>>>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>>>
>>>>>>>>>>>>> Thanks Bob,
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Good advice! The best way to get around this would be to use the
repeater as a signal generator after tuning - will try that next one I do.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will
check the spec.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>
>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>
>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> It seems to me that your biggest concern would be with
frequency accuracy. No way to sinc the nanVNA with an external GPS
disciplined time base. You may tune the diplexer a few kHz off the desired
channel.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Very detailed response! Fixturing in this case would seem
less relevant with duplexers? They’re solidly built with n connectors. The
actual attenuation in the stop band isn’t as important as being able to
accurately tune for the null. Using the earlier model nano VNAs there was no
way to reduce the bandwidth as in the Fieldfox. The pro version seems to allow
quite narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>
>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> High isolation measurements are often more fixture limited
than instrument limited.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit for
a 16 bit ADC.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> The actual measurement SNR might be different - better,
because multiple ADC samples are averaged; worse, because a 16 bit ADC usually
has 13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like that.
You’d need a precise attenuator with 96 dB attenuation, for instance. That’s
no trivial matter.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Usually what you do is measure a few signals at various
larger levels, and then assume (verify) linearity, and extrapolate down to
the noise floor.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
>>>>>>>>
>>>>>>>>> > > > _._,_._,_
* * *
Hi Bob,
I’m sure all the NanoVNA models have square wave outputs, as does the
Fieldfox. My objective here was to look at the fundamental frequency on a gps
disciplined SA to see how far off frequency it was when set to 440MHz. The
existence of all the harmonics shouldn’t be a problem tuning a duplexer, but
could be with other DUTs.
Best regards,
Rob Rowlands
415 849 5667
> On Mar 20, 2024, at 8:43 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> Rob,
>
> Your VNA model is different from my nanoVNA V2 Plus four in that the "CW"
output on mine is a square wave and thus has infinite sidebands aand appears
as a very broad signal on my spectrum analyzer. However, the center frequency
does seem to be reasonably accurate. Attached photos show the signal in a 2
MHz span, one on auto and one on a slow one second sweep. Going to a 2 kHz
sweep like on your Field Fox gives a line across the top..
>
>
>
>
>
>
>
> On Wed, Mar 20, 2024 at 8:34 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>> That looks really good. Perhaps my counter has difficulty with the nest
square wave output. I’ll try looking at it with a spectrum analyzer and an
oscilloscope.
>>
>>
>
>>
>> On Wed, Mar 20, 2024 at 6:00 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>
>>> Hi Bob, __ __
>>>
>>> __ __
>>>
>>> I just tested the 440MHz CW output of my NanoVNA-H4 with the Fieldfox
sync’d to GPS. __ __
>>>
>>> __ __
>>>
>>> Attached is the FF Spectrum Analyzer plot with markers showing the Nano
output at 439.99924MHz. This would be 760Hz low, or 1.73ppm if my math is
correct. Not bad don’t you think? I used to work with stratum 3 telecom clocks
at 4.6ppm! __ __
>>>
>>> __ __
>>>
>>> I also looked at the frequency delta between the FieldFox internal clock
and GPS, and only saw about 100Hz. I would have expected your HP 5385 counter
to be better as it probably has an oven? __ __
>>>
>>> __ __
>>>
>>> Just for giggles I have ordered this OCXO from Amazon that should be
interesting – for $20 it might be
useful.[https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
Also ordered a $60 GPS disciplined source from Ali express
[https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa)
__ __
>>>
>>> __ __
>>>
>>> Keeping time here.. __ __
>>>
>>> __ __
>>>
>>> 73, __ __
>>>
>>> __ __
>>>
>>> Rob NZ6J __ __
>>>
>>> 415 849 5667 __ __
>>>
>>> __ __
>>>
>>> __ __
>>>
>>> **From:** [NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
<[NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)> **On Behalf Of** Bob W0EG
> **Sent:** Tuesday, March 19, 2024 8:37 AM
> **To:** [NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro __ __
>>>
>>> __ __
>>>
>>> I should note that the “CW” output from the nano is not a pure sine wave,
more of a rounded off square wave. So it is possible that the counter may
have issues with the signal. I try to have a look at it on a spectrum
analyzer also synced to the 10MHz reference. Also, when measuring a 10MHz
signal on this counter, removing the GPS reference only changed the reading by
twenty five Hz. __ __
>>>
>>> __ __
>>>
>>> On Tue, Mar 19, 2024 at 11:14 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>
>>>> < image001.jpg>
>>>>
>>>> __ __
>>>>
>>>> __ __
>>>>
>>>> __ __
>>>>
>>>> On Tue, Mar 19, 2024 at 10:11 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>
>>>>> < image002.jpg>
>>>>>
>>>>> __ __
>>>>>
>>>>> NanoVNA set to CW 440 MHz. Off by over 500kHz __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> On Tue, Mar 19, 2024 at 12:59 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>
>>>>>> That kind of thing is why the FieldFox costs what it does. __ __
>>>>>>
>>>>>> It could be added to PC software pretty easily, not sure it would fit
in the firmware in the NanoVNA2 itself. __ __
>>>>>>
>>>>>> But while it’s just a few lines of code to implement, it does have a
“maintenance tail” __ __
>>>>>>
>>>>>> __ __
>>>>>>
>>>>>>
>
> __ __
>>>>>>
>>>>>>> On Mar 18, 2024, at 8:29 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>
>>>>>>> __ __
>>>>>>
>>>>>>> The Keysight Fieldfox has a PC program that will adjust the TCXO to
match a connected 10MHz reference. I will check my nanoVNA with a frequency
counter connected to a GPS reference. __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>
>>>>>>>> I’m tuning duplexers for ham 440 repeaters __ __
>>>>>>>>
>>>>>>>> Best regards, __ __
>>>>>>>>
>>>>>>>> Rob Rowlands __ __
>>>>>>>>
>>>>>>>> 415 849 5667 __ __
>>>>>>>>
>>>>>>>>
>
> __ __
>>>>>>>>
>>>>>>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>
>>>>>>>>> __ __
>>>>>>>>
>>>>>>>>> I am confused. Why do you need a diplexer for FM broadcast
transmission? Coupling two transmitters on different channels to a single
antenna? I usually associate diplexers with repeaters. __ __
>>>>>>>>>
>>>>>>>>> __ __
>>>>>>>>>
>>>>>>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>
>>>>>>>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20
ppm frequency tolerance is just fine. __ __
>>>>>>>>>>
>>>>>>>>>> __ __
>>>>>>>>>>
>>>>>>>>>>
>
> __ __
>>>>>>>>>>
>>>>>>>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>
>>>>>>>>>>> __ __
>>>>>>>>>>
>>>>>>>>>>> __ __
>>>>>>>>>>>
>>>>>>>>>>> I thought the OP was tuning duplexes for amateur radio repeaters.
Ham FM uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
__ __
>>>>>>>>>>>
>>>>>>>>>>> __ __
>>>>>>>>>>>
>>>>>>>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>
>>>>>>>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very
critical (the detector is insensitive to it). And licensing makes sure that
nobody else on your channel is anywhere close to near your power, so yeah,
capture effect. __ __
>>>>>>>>>>>>
>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>> On AM you could get heterodynes, but just as with FM, your
license protects you from anyone close by. Aircraft use AM, and heterodynes
are a feature of life. __ __
>>>>>>>>>>>>
>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>> Broadcast doesn’t use SSB (in general), which is where frequency
accuracy would be important, for “no need to use clarifier” on speech. 20Hz
(1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be
intolerable. __ __
>>>>>>>>>>>>
>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>> There are “simulbroadcast” on the same frequency in EU for TV
(and maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better. __ __
>>>>>>>>>>>>
>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>
>>>>>>>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>
>>>>>>>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them? __ __
>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz,
that’s 20 ppm, which is fairly loose. In practice, they probably are better,
but no guarantees. __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Same for AM - 20 ppm. __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> WWV would be better (but is kind of weak unless you live in Ft.
Collins or Kauai) __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Hi Bob, __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test. __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> < image0.jpeg> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> When I’ve time I will do the same test with my Keysight
Fieldfox. __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the
best equipment drifts and the the crystal ages so require re-calibration.
I’ll try checking mine with a frequency counter using a GOS reference. __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Thanks Bob, __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Good advice! The best way to get around this would be to use
the repeater as a signal generator after tuning - will try that next one I do.
__ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will
check the spec. __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> It seems to me that your biggest concern would be with
frequency accuracy. No way to sinc the nanVNA with an external GPS
disciplined time base. You may tune the diplexer a few kHz off the desired
channel. __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Thanks Jim, __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Very detailed response! Fixturing in this case would
seem less relevant with duplexers? They’re solidly built with n connectors.
The actual attenuation in the stop band isn’t as important as being able to
accurately tune for the null. Using the earlier model nano VNAs there was no
way to reduce the bandwidth as in the Fieldfox. The pro version seems to allow
quite narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense! __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> High isolation measurements are often more fixture
limited than instrument limited. __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit
for a 16 bit ADC. __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> The actual measurement SNR might be different - better,
because multiple ADC samples are averaged; worse, because a 16 bit ADC usually
has 13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc. __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like
that. You’d need a precise attenuator with 96 dB attenuation, for instance.
That’s no trivial matter. __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Usually what you do is measure a few signals at various
larger levels, and then assume (verify) linearity, and extrapolate down to
the noise floor. __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J ____
>>>
>>> __
>
> <IMG_5049.JPG>
>
> <IMG_5048.JPG>
>
> <IMG_5046.JPG>
_._,_._,_
* * *
10 MHz CW output form my nano.
On Wed, Mar 20, 2024 at 11:43 AM Bob W0EG via groups.io <morrisnc7=
gmail.com@groups.io> wrote:
Hi Bob,
I did some harmonic analysis on the GPS Disciplined FieldFox of my two NanoVNAs and also the Sig Gen output on my Tiny SA Ultra, with very interesting results:
1. The NanoVNA-F V2 gave the expected integer multiples of 440MHz with odd harmonics dominant
2. The NanoVNA-H 4 unusually had non integer “harmonics”, suggesting it generates its stimulus by heterodyning?
3.
My TinySA Ultra signal generator mode produced no visible harmonics and was also very close to nominal 440MHz
This is a detailed span at 2kHz, using the same setup I used on the Nano – while its hard to believe Tiny SA sig gen appears to be only 40 Hz off nominal . Just to be sure I checked that the Fieldfox GPS receiver is seeing 14 satellites.
My bottom line on all this is that I needn’t worry about frequency accuracy using these low cost RF tools to tune duplexers. Your opinion?
73,
Rob
415 849 5667
Hi Bob,
Is it possible the flat spectrum you saw on 2kHz span was from the RBW
setting? I saw the same thing on my Fieldfox, but choosing auto RBW took care
of it!
Best regards,
Rob Rowlands
415 849 5667
> On Mar 20, 2024, at 10:55 AM, Rob Rowlands <rowlands47@gmail.com> wrote:
>
>
>
>
> Hi Bob,
>
>
>
> I did some harmonic analysis on the GPS Disciplined FieldFox of my two
NanoVNAs and also the Sig Gen output on my Tiny SA Ultra, with very
interesting results:
>
>
>
> 1. The NanoVNA-F V2 gave the expected integer multiples of 440MHz with odd
harmonics dominant
>
>
> <image003.jpg>
>
>
>
>
> 2. The NanoVNA-H 4 unusually had non integer “harmonics”, suggesting it
generates its stimulus by heterodyning?
>
>
> 3. <image004.jpg>
>
>
>
>
>
>
>
> My TinySA Ultra signal generator mode produced no visible harmonics and was
also very close to nominal 440MHz
>
>
>
>
> <image005.jpg>
>
> This is a detailed span at 2kHz, using the same setup I used on the Nano –
while its hard to believe Tiny SA sig gen appears to be only 40 Hz off nominal
. Just to be sure I checked that the Fieldfox GPS receiver is seeing 14
satellites.
>
>
>
> <image006.jpg>
>
> My bottom line on all this is that I needn’t worry about frequency accuracy
using these low cost RF tools to tune duplexers. Your opinion?
>
>
>
> 73,
>
>
>
> Rob
>
> 415 849 5667
>
>
>
> **From:** NanoVNAV2@groups.io <NanoVNAV2@groups.io> **On Behalf Of** Bob
W0EG
> **Sent:** Wednesday, March 20, 2024 7:48 AM
> **To:** NanoVNAV2@groups.io
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro
>
>
>
> Rob,
>
> Your VNA model is different from my nanoVNA V2 Plus four in that the "CW"
output on mine is a square wave and thus has infinite sidebands aand appears
as a very broad signal on my spectrum analyzer. However, the center frequency
does seem to be reasonably accurate. Attached photos show the signal in a 2
MHz span, one on auto and one on a slow one second sweep. Going to a 2 kHz
sweep like on your Field Fox gives a line across the top..
>
>
>
>
>
> On Wed, Mar 20, 2024 at 8:34 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>> That looks really good. Perhaps my counter has difficulty with the nest
square wave output. I’ll try looking at it with a spectrum analyzer and an
oscilloscope.
>>
>>
>>
>> On Wed, Mar 20, 2024 at 6:00 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>
>>> Hi Bob,
>>>
>>>
>>>
>>> I just tested the 440MHz CW output of my NanoVNA-H4 with the Fieldfox
sync’d to GPS.
>>>
>>>
>>>
>>> Attached is the FF Spectrum Analyzer plot with markers showing the Nano
output at 439.99924MHz. This would be 760Hz low, or 1.73ppm if my math is
correct. Not bad don’t you think? I used to work with stratum 3 telecom clocks
at 4.6ppm!
>>>
>>>
>>>
>>> I also looked at the frequency delta between the FieldFox internal clock
and GPS, and only saw about 100Hz. I would have expected your HP 5385 counter
to be better as it probably has an oven?
>>>
>>>
>>>
>>> Just for giggles I have ordered this OCXO from Amazon that should be
interesting – for $20 it might be useful.
[https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
Also ordered a $60 GPS disciplined source from Ali express
[https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa)
>>>
>>>
>>>
>>> Keeping time here..
>>>
>>>
>>>
>>> 73,
>>>
>>>
>>>
>>> Rob NZ6J
>>>
>>> 415 849 5667
>>>
>>>
>>>
>>>
>>>
>>> **From:** [ NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
<[NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)> **On Behalf Of** Bob W0EG
> **Sent:** Tuesday, March 19, 2024 8:37 AM
> **To:** [ NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro
>>>
>>>
>>>
>>> I should note that the “CW” output from the nano is not a pure sine wave,
more of a rounded off square wave. So it is possible that the counter may
have issues with the signal. I try to have a look at it on a spectrum
analyzer also synced to the 10MHz reference. Also, when measuring a 10MHz
signal on this counter, removing the GPS reference only changed the reading by
twenty five Hz.
>>>
>>>
>>>
>>> On Tue, Mar 19, 2024 at 11:14 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>
>>>> <image001.jpg>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Tue, Mar 19, 2024 at 10:11 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>
>>>>> <image002.jpg>
>>>>>
>>>>> NanoVNA set to CW 440 MHz. Off by over 500kHz
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Mar 19, 2024 at 12:59 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>
>>>>>> That kind of thing is why the FieldFox costs what it does.
>>>>>>
>>>>>> It could be added to PC software pretty easily, not sure it would fit
in the firmware in the NanoVNA2 itself.
>>>>>>
>>>>>> But while it’s just a few lines of code to implement, it does have a
“maintenance tail”
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> On Mar 18, 2024, at 8:29 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>
>>>>>>>
>>>>>>
>>>>>>> The Keysight Fieldfox has a PC program that will adjust the TCXO to
match a connected 10MHz reference. I will check my nanoVNA with a frequency
counter connected to a GPS reference.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>
>>>>>>>> I’m tuning duplexers for ham 440 repeaters
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>>
>>>>>>>> Rob Rowlands
>>>>>>>>
>>>>>>>> 415 849 5667
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>> I am confused. Why do you need a diplexer for FM broadcast
transmission? Coupling two transmitters on different channels to a single
antenna? I usually associate diplexers with repeaters.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>
>>>>>>>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20
ppm frequency tolerance is just fine.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> I thought the OP was tuning duplexes for amateur radio repeaters.
Ham FM uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very
critical (the detector is insensitive to it). And licensing makes sure that
nobody else on your channel is anywhere close to near your power, so yeah,
capture effect.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On AM you could get heterodynes, but just as with FM, your
license protects you from anyone close by. Aircraft use AM, and heterodynes
are a feature of life.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Broadcast doesn’t use SSB (in general), which is where frequency
accuracy would be important, for “no need to use clarifier” on speech. 20Hz
(1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be
intolerable.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> There are “simulbroadcast” on the same frequency in EU for TV
(and maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them?
>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>
>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>
>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz,
that’s 20 ppm, which is fairly loose. In practice, they probably are better,
but no guarantees.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Same for AM - 20 ppm.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> WWV would be better (but is kind of weak unless you live in Ft.
Collins or Kauai)
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Hi Bob,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> <image0.jpeg>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> When I’ve time I will do the same test with my Keysight
Fieldfox.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the
best equipment drifts and the the crystal ages so require re-calibration.
I’ll try checking mine with a frequency counter using a GOS reference.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Thanks Bob,
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Good advice! The best way to get around this would be to use
the repeater as a signal generator after tuning - will try that next one I do.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will
check the spec.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> It seems to me that your biggest concern would be with
frequency accuracy. No way to sinc the nanVNA with an external GPS
disciplined time base. You may tune the diplexer a few kHz off the desired
channel.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Very detailed response! Fixturing in this case would seem
less relevant with duplexers? They’re solidly built with n connectors. The
actual attenuation in the stop band isn’t as important as being able to
accurately tune for the null. Using the earlier model nano VNAs there was no
way to reduce the bandwidth as in the Fieldfox. The pro version seems to allow
quite narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> High isolation measurements are often more fixture
limited than instrument limited.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit
for a 16 bit ADC.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> The actual measurement SNR might be different - better,
because multiple ADC samples are averaged; worse, because a 16 bit ADC usually
has 13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like
that. You’d need a precise attenuator with 96 dB attenuation, for instance.
That’s no trivial matter.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Usually what you do is measure a few signals at various
larger levels, and then assume (verify) linearity, and extrapolate down to
the noise floor.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
On Tue, Mar 19, 2024 at 09:29 AM, Jim Lux wrote:
>
> NOAA Weather radio is FM, so you’d not hear heterodynes.
So are 2 meter ham repeaters FM. There is a system here in Washington State that has a number of repeaters on the same frequency, and I can hear always at least two of them at my house, and I think sometimes three, possibly more. Take my word for it, you do hear heterodynes on FM. I have a little elevation at my house, and I hear things that those in town probably do not hear, so the majority of the system users probably don't have to put up with what I put up with. I'll put it this way: I do not have that frequency in my scan list.
On Fri, Mar 15, 2024 at 10:39 AM, Jim Lux wrote:
>
> What’s the accuracy of the TinySA?
I believe the tinySA Ultra is rated at ±1 pm over -10 to +50° C.
Rob,
The clean signal in your photo sure looks like a sign wave. I don’t see any
side bands. Can you post a photo with a wider span? My nano seems
different. I would be surprised if a very expensive analyzer like the
Keysight Fieldfox had square wave outputs.
On Thu, Mar 21, 2024 at 12:29 AM Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
I have an old HP 8945E analyzer and the RBW only goes down to 1KHz. It was
in auto but changing BW to 1KHz gives the same result. I’ll see if I can
access a better analyzer some time next week (after recovering from COVID).
On Thu, Mar 21, 2024 at 12:30 AM Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
The one with every harmonic (not just odd) means that the output isn’t a
square wave, it’s pulses. The lower the duty cycle (i.e. narrower the pulses
relative to the period) the less quickly the harmonics fall off. In the limit
(an infinitely narrow pulse), the power spectrum is a series of impulses of
equal amplitude.
> On Mar 20, 2024, at 9:33 PM, Rob Rowlands NZ6J <rowlands47@gmail.com> wrote:
>
>
>
>
> Hi Bob,
>
>
>
> I did some harmonic analysis on the GPS Disciplined FieldFox of my two
NanoVNAs and also the Sig Gen output on my Tiny SA Ultra, with very
interesting results:
>
>
>
> 1. The NanoVNA-F V2 gave the expected integer multiples of 440MHz with odd
harmonics dominant
>
>
> <image003.jpg>
>
>
>
>
> 2. The NanoVNA-H 4 unusually had non integer “harmonics”, suggesting it
generates its stimulus by heterodyning?
>
>
> 3. <image004.jpg>
>
>
>
>
>
>
>
> My TinySA Ultra signal generator mode produced no visible harmonics and was
also very close to nominal 440MHz
>
>
>
>
> <image005.jpg>
>
> This is a detailed span at 2kHz, using the same setup I used on the Nano –
while its hard to believe Tiny SA sig gen appears to be only 40 Hz off nominal
. Just to be sure I checked that the Fieldfox GPS receiver is seeing 14
satellites.
>
>
>
> <image006.jpg>
>
> My bottom line on all this is that I needn’t worry about frequency accuracy
using these low cost RF tools to tune duplexers. Your opinion?
>
>
>
> 73,
>
>
>
> Rob
>
> 415 849 5667
>
>
>
> **From:** NanoVNAV2@groups.io <NanoVNAV2@groups.io> **On Behalf Of** Bob
W0EG
> **Sent:** Wednesday, March 20, 2024 7:48 AM
> **To:** NanoVNAV2@groups.io
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro
>
>
>
> Rob,
>
> Your VNA model is different from my nanoVNA V2 Plus four in that the "CW"
output on mine is a square wave and thus has infinite sidebands aand appears
as a very broad signal on my spectrum analyzer. However, the center frequency
does seem to be reasonably accurate. Attached photos show the signal in a 2
MHz span, one on auto and one on a slow one second sweep. Going to a 2 kHz
sweep like on your Field Fox gives a line across the top..
>
>
>
>
>
> On Wed, Mar 20, 2024 at 8:34 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>> That looks really good. Perhaps my counter has difficulty with the nest
square wave output. I’ll try looking at it with a spectrum analyzer and an
oscilloscope.
>>
>>
>>
>> On Wed, Mar 20, 2024 at 6:00 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>
>>> Hi Bob,
>>>
>>>
>>>
>>> I just tested the 440MHz CW output of my NanoVNA-H4 with the Fieldfox
sync’d to GPS.
>>>
>>>
>>>
>>> Attached is the FF Spectrum Analyzer plot with markers showing the Nano
output at 439.99924MHz. This would be 760Hz low, or 1.73ppm if my math is
correct. Not bad don’t you think? I used to work with stratum 3 telecom clocks
at 4.6ppm!
>>>
>>>
>>>
>>> I also looked at the frequency delta between the FieldFox internal clock
and GPS, and only saw about 100Hz. I would have expected your HP 5385 counter
to be better as it probably has an oven?
>>>
>>>
>>>
>>> Just for giggles I have ordered this OCXO from Amazon that should be
interesting – for $20 it might be useful.
[https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
Also ordered a $60 GPS disciplined source from Ali express
[https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa)
>>>
>>>
>>>
>>> Keeping time here..
>>>
>>>
>>>
>>> 73,
>>>
>>>
>>>
>>> Rob NZ6J
>>>
>>> 415 849 5667
>>>
>>>
>>>
>>>
>>>
>>> **From:** [ NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
<[NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)> **On Behalf Of** Bob W0EG
> **Sent:** Tuesday, March 19, 2024 8:37 AM
> **To:** [ NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro
>>>
>>>
>>>
>>> I should note that the “CW” output from the nano is not a pure sine wave,
more of a rounded off square wave. So it is possible that the counter may
have issues with the signal. I try to have a look at it on a spectrum
analyzer also synced to the 10MHz reference. Also, when measuring a 10MHz
signal on this counter, removing the GPS reference only changed the reading by
twenty five Hz.
>>>
>>>
>>>
>>> On Tue, Mar 19, 2024 at 11:14 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>
>>>> <image001.jpg>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Tue, Mar 19, 2024 at 10:11 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>
>>>>> <image002.jpg>
>>>>>
>>>>> NanoVNA set to CW 440 MHz. Off by over 500kHz
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Mar 19, 2024 at 12:59 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>
>>>>>> That kind of thing is why the FieldFox costs what it does.
>>>>>>
>>>>>> It could be added to PC software pretty easily, not sure it would fit
in the firmware in the NanoVNA2 itself.
>>>>>>
>>>>>> But while it’s just a few lines of code to implement, it does have a
“maintenance tail”
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> On Mar 18, 2024, at 8:29 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>
>>>>>>>
>>>>>>
>>>>>>> The Keysight Fieldfox has a PC program that will adjust the TCXO to
match a connected 10MHz reference. I will check my nanoVNA with a frequency
counter connected to a GPS reference.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>
>>>>>>>> I’m tuning duplexers for ham 440 repeaters
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>>
>>>>>>>> Rob Rowlands
>>>>>>>>
>>>>>>>> 415 849 5667
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>> I am confused. Why do you need a diplexer for FM broadcast
transmission? Coupling two transmitters on different channels to a single
antenna? I usually associate diplexers with repeaters.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>
>>>>>>>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20
ppm frequency tolerance is just fine.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> I thought the OP was tuning duplexes for amateur radio repeaters.
Ham FM uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very
critical (the detector is insensitive to it). And licensing makes sure that
nobody else on your channel is anywhere close to near your power, so yeah,
capture effect.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On AM you could get heterodynes, but just as with FM, your
license protects you from anyone close by. Aircraft use AM, and heterodynes
are a feature of life.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Broadcast doesn’t use SSB (in general), which is where frequency
accuracy would be important, for “no need to use clarifier” on speech. 20Hz
(1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be
intolerable.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> There are “simulbroadcast” on the same frequency in EU for TV
(and maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them?
>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>
>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>
>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz,
that’s 20 ppm, which is fairly loose. In practice, they probably are better,
but no guarantees.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Same for AM - 20 ppm.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> WWV would be better (but is kind of weak unless you live in Ft.
Collins or Kauai)
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Hi Bob,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> <image0.jpeg>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> When I’ve time I will do the same test with my Keysight
Fieldfox.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the
best equipment drifts and the the crystal ages so require re-calibration.
I’ll try checking mine with a frequency counter using a GOS reference.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Thanks Bob,
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Good advice! The best way to get around this would be to use
the repeater as a signal generator after tuning - will try that next one I do.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor? Will
check the spec.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> It seems to me that your biggest concern would be with
frequency accuracy. No way to sinc the nanVNA with an external GPS
disciplined time base. You may tune the diplexer a few kHz off the desired
channel.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Very detailed response! Fixturing in this case would seem
less relevant with duplexers? They’re solidly built with n connectors. The
actual attenuation in the stop band isn’t as important as being able to
accurately tune for the null. Using the earlier model nano VNAs there was no
way to reduce the bandwidth as in the Fieldfox. The pro version seems to allow
quite narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> High isolation measurements are often more fixture
limited than instrument limited.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit
for a 16 bit ADC.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> The actual measurement SNR might be different - better,
because multiple ADC samples are averaged; worse, because a 16 bit ADC usually
has 13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like
that. You’d need a precise attenuator with 96 dB attenuation, for instance.
That’s no trivial matter.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Usually what you do is measure a few signals at various
larger levels, and then assume (verify) linearity, and extrapolate down to
the noise floor.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
I’m pretty sure the Keysight FieldFox has a sine output. It may not have the
spectral purity of a good RF signal generator, but significant harmonic
content in a $10,000 instrument would be unusual.
> On Mar 20, 2024, at 9:29 PM, Rob Rowlands NZ6J <rowlands47@gmail.com> wrote:
>
>
> Hi Bob,
>
>
>
>
> I’m sure all the NanoVNA models have square wave outputs, as does the
Fieldfox. My objective here was to look at the fundamental frequency on a gps
disciplined SA to see how far off frequency it was when set to 440MHz. The
existence of all the harmonics shouldn’t be a problem tuning a duplexer, but
could be with other DUTs.
>
>
>
>
> Best regards,
>
> Rob Rowlands
>
> 415 849 5667
>
>
>
>
>> On Mar 20, 2024, at 8:43 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>>
>>
>> Rob,
>>
>> Your VNA model is different from my nanoVNA V2 Plus four in that the "CW"
output on mine is a square wave and thus has infinite sidebands aand appears
as a very broad signal on my spectrum analyzer. However, the center frequency
does seem to be reasonably accurate. Attached photos show the signal in a 2
MHz span, one on auto and one on a slow one second sweep. Going to a 2 kHz
sweep like on your Field Fox gives a line across the top..
>>
>>
>
>>
>>
>
>>
>> On Wed, Mar 20, 2024 at 8:34 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>>
>>> That looks really good. Perhaps my counter has difficulty with the nest
square wave output. I’ll try looking at it with a spectrum analyzer and an
oscilloscope.
>>>
>>>
>
>>>
>>> On Wed, Mar 20, 2024 at 6:00 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>
>>>> Hi Bob, __ __
>>>>
>>>> __ __
>>>>
>>>> I just tested the 440MHz CW output of my NanoVNA-H4 with the Fieldfox
sync’d to GPS. __ __
>>>>
>>>> __ __
>>>>
>>>> Attached is the FF Spectrum Analyzer plot with markers showing the Nano
output at 439.99924MHz. This would be 760Hz low, or 1.73ppm if my math is
correct. Not bad don’t you think? I used to work with stratum 3 telecom clocks
at 4.6ppm! __ __
>>>>
>>>> __ __
>>>>
>>>> I also looked at the frequency delta between the FieldFox internal clock
and GPS, and only saw about 100Hz. I would have expected your HP 5385 counter
to be better as it probably has an oven? __ __
>>>>
>>>> __ __
>>>>
>>>> Just for giggles I have ordered this OCXO from Amazon that should be
interesting – for $20 it might be
useful.[https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
Also ordered a $60 GPS disciplined source from Ali express
[https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa)
__ __
>>>>
>>>> __ __
>>>>
>>>> Keeping time here.. __ __
>>>>
>>>> __ __
>>>>
>>>> 73, __ __
>>>>
>>>> __ __
>>>>
>>>> Rob NZ6J __ __
>>>>
>>>> 415 849 5667 __ __
>>>>
>>>> __ __
>>>>
>>>> __ __
>>>>
>>>> **From:** [NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
<[NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)> **On Behalf Of** Bob W0EG
> **Sent:** Tuesday, March 19, 2024 8:37 AM
> **To:** [NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro __ __
>>>>
>>>> __ __
>>>>
>>>> I should note that the “CW” output from the nano is not a pure sine wave,
more of a rounded off square wave. So it is possible that the counter may
have issues with the signal. I try to have a look at it on a spectrum
analyzer also synced to the 10MHz reference. Also, when measuring a 10MHz
signal on this counter, removing the GPS reference only changed the reading by
twenty five Hz. __ __
>>>>
>>>> __ __
>>>>
>>>> On Tue, Mar 19, 2024 at 11:14 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>
>>>>> < image001.jpg>
>>>>>
>>>>> __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> On Tue, Mar 19, 2024 at 10:11 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>
>>>>>> < image002.jpg>
>>>>>>
>>>>>> __ __
>>>>>>
>>>>>> NanoVNA set to CW 440 MHz. Off by over 500kHz __ __
>>>>>>
>>>>>> __ __
>>>>>>
>>>>>> On Tue, Mar 19, 2024 at 12:59 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>
>>>>>>> That kind of thing is why the FieldFox costs what it does. __ __
>>>>>>>
>>>>>>> It could be added to PC software pretty easily, not sure it would fit
in the firmware in the NanoVNA2 itself. __ __
>>>>>>>
>>>>>>> But while it’s just a few lines of code to implement, it does have a
“maintenance tail” __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>>
>
> __ __
>>>>>>>
>>>>>>>> On Mar 18, 2024, at 8:29 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>
>>>>>>>> __ __
>>>>>>>
>>>>>>>> The Keysight Fieldfox has a PC program that will adjust the TCXO to
match a connected 10MHz reference. I will check my nanoVNA with a frequency
counter connected to a GPS reference. __ __
>>>>>>>>
>>>>>>>> __ __
>>>>>>>>
>>>>>>>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>
>>>>>>>>> I’m tuning duplexers for ham 440 repeaters __ __
>>>>>>>>>
>>>>>>>>> Best regards, __ __
>>>>>>>>>
>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>
>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>
>>>>>>>>>
>
> __ __
>>>>>>>>>
>>>>>>>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>
>>>>>>>>>> __ __
>>>>>>>>>
>>>>>>>>>> I am confused. Why do you need a diplexer for FM broadcast
transmission? Coupling two transmitters on different channels to a single
antenna? I usually associate diplexers with repeaters. __ __
>>>>>>>>>>
>>>>>>>>>> __ __
>>>>>>>>>>
>>>>>>>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>
>>>>>>>>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20
ppm frequency tolerance is just fine. __ __
>>>>>>>>>>>
>>>>>>>>>>> __ __
>>>>>>>>>>>
>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>
>>>>>>>>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>
>>>>>>>>>>>> __ __
>>>>>>>>>>>
>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>> I thought the OP was tuning duplexes for amateur radio repeaters.
Ham FM uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
__ __
>>>>>>>>>>>>
>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>
>>>>>>>>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very
critical (the detector is insensitive to it). And licensing makes sure that
nobody else on your channel is anywhere close to near your power, so yeah,
capture effect. __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> On AM you could get heterodynes, but just as with FM, your
license protects you from anyone close by. Aircraft use AM, and heterodynes
are a feature of life. __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> Broadcast doesn’t use SSB (in general), which is where frequency
accuracy would be important, for “no need to use clarifier” on speech. 20Hz
(1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be
intolerable. __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> There are “simulbroadcast” on the same frequency in EU for TV
(and maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better. __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them? __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100
MHz, that’s 20 ppm, which is fairly loose. In practice, they probably are
better, but no guarantees. __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Same for AM - 20 ppm. __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> WWV would be better (but is kind of weak unless you live in
Ft. Collins or Kauai) __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Hi Bob, __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test. __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> < image0.jpeg> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> When I’ve time I will do the same test with my Keysight
Fieldfox. __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even
the best equipment drifts and the the crystal ages so require re-calibration.
I’ll try checking mine with a frequency counter using a GOS reference. __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Thanks Bob, __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Good advice! The best way to get around this would be to
use the repeater as a signal generator after tuning - will try that next one I
do. __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor?
Will check the spec. __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> It seems to me that your biggest concern would be with
frequency accuracy. No way to sinc the nanVNA with an external GPS
disciplined time base. You may tune the diplexer a few kHz off the desired
channel. __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Thanks Jim, __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Very detailed response! Fixturing in this case would
seem less relevant with duplexers? They’re solidly built with n connectors.
The actual attenuation in the stop band isn’t as important as being able to
accurately tune for the null. Using the earlier model nano VNAs there was no
way to reduce the bandwidth as in the Fieldfox. The pro version seems to allow
quite narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense! __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> High isolation measurements are often more fixture
limited than instrument limited. __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit
for a 16 bit ADC. __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> The actual measurement SNR might be different - better,
because multiple ADC samples are averaged; worse, because a 16 bit ADC usually
has 13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc. __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like
that. You’d need a precise attenuator with 96 dB attenuation, for instance.
That’s no trivial matter. __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Usually what you do is measure a few signals at various
larger levels, and then assume (verify) linearity, and extrapolate down to
the noise floor. __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J ____
>>>>
>>>> __
>>
>> <IMG_5049.JPG>
>>
>> <IMG_5048.JPG>
>>
>> <IMG_5046.JPG>
_._,_._,_
* * *
Probably why my counters have trouble accuracy measuring the frequency. Of
course a near true square wave at 440 MHz would require a nano second rise
time and not possible in such a low cost instrument. My oscilloscope has
a rated 200 MHz bandwidth so I will further round off the rise time.
Looking at the 440 MHz signal on the scope, it appears unstable.
On Thu, Mar 21, 2024 at 11:59 AM Jim Lux <jimlux@earthlink.net> wrote:
Hi Bob,
Here’s the wider plot showing 3rd harmonic down 23dB, not a square wave but
definitely not a pure sinewave. My understanding is VNAs have tunable receive
filters, so harmonic content of the generator isn't material.
Best regards,
Rob Rowlands
415 849 5667
> On Mar 21, 2024, at 8:59 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> Rob,
>
>
>
>
> The clean signal in your photo sure looks like a sign wave. I don’t see any
side bands. Can you post a photo with a wider span? My nano seems different.
I would be surprised if a very expensive analyzer like the Keysight Fieldfox
had square wave outputs.
>
>
>
>
> On Thu, Mar 21, 2024 at 12:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>> Hi Bob,
>>
>>
>
>>
>> I’m sure all the NanoVNA models have square wave outputs, as does the
Fieldfox. My objective here was to look at the fundamental frequency on a gps
disciplined SA to see how far off frequency it was when set to 440MHz. The
existence of all the harmonics shouldn’t be a problem tuning a duplexer, but
could be with other DUTs.
>>
>>
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 20, 2024, at 8:43 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>
>>>
>>>
>>> Rob,
>>>
>>> Your VNA model is different from my nanoVNA V2 Plus four in that the "CW"
output on mine is a square wave and thus has infinite sidebands aand appears
as a very broad signal on my spectrum analyzer. However, the center frequency
does seem to be reasonably accurate. Attached photos show the signal in a 2
MHz span, one on auto and one on a slow one second sweep. Going to a 2 kHz
sweep like on your Field Fox gives a line across the top..
>>>
>>>
>
>>>
>>>
>
>>>
>>> On Wed, Mar 20, 2024 at 8:34 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>>>
>>>> That looks really good. Perhaps my counter has difficulty with the nest
square wave output. I’ll try looking at it with a spectrum analyzer and an
oscilloscope.
>>>>
>>>>
>
>>>>
>>>> On Wed, Mar 20, 2024 at 6:00 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>
>>>>> Hi Bob, __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> I just tested the 440MHz CW output of my NanoVNA-H4 with the Fieldfox
sync’d to GPS. __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> Attached is the FF Spectrum Analyzer plot with markers showing the Nano
output at 439.99924MHz. This would be 760Hz low, or 1.73ppm if my math is
correct. Not bad don’t you think? I used to work with stratum 3 telecom clocks
at 4.6ppm! __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> I also looked at the frequency delta between the FieldFox internal clock
and GPS, and only saw about 100Hz. I would have expected your HP 5385 counter
to be better as it probably has an oven? __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> Just for giggles I have ordered this OCXO from Amazon that should be
interesting – for $20 it might be
useful.[https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
Also ordered a $60 GPS disciplined source from Ali express
[https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa)
__ __
>>>>>
>>>>> __ __
>>>>>
>>>>> Keeping time here.. __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> 73, __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> Rob NZ6J __ __
>>>>>
>>>>> 415 849 5667 __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> **From:** [NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
<[NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)> **On Behalf Of** Bob W0EG
> **Sent:** Tuesday, March 19, 2024 8:37 AM
> **To:** [NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> I should note that the “CW” output from the nano is not a pure sine
wave, more of a rounded off square wave. So it is possible that the counter
may have issues with the signal. I try to have a look at it on a spectrum
analyzer also synced to the 10MHz reference. Also, when measuring a 10MHz
signal on this counter, removing the GPS reference only changed the reading by
twenty five Hz. __ __
>>>>>
>>>>> __ __
>>>>>
>>>>> On Tue, Mar 19, 2024 at 11:14 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>
>>>>>> < image001.jpg>
>>>>>>
>>>>>> __ __
>>>>>>
>>>>>> __ __
>>>>>>
>>>>>> __ __
>>>>>>
>>>>>> On Tue, Mar 19, 2024 at 10:11 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>
>>>>>>> < image002.jpg>
>>>>>>>
>>>>>>> __ __
>>
>>> > > > > NanoVNA set to CW 440 MHz. Off by over 500kHz __ __
>>
>>> > > > > > > > > > __ __
>>>>>>>
>>>>>>> On Tue, Mar 19, 2024 at 12:59 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>
>>>>>>>> That kind of thing is why the FieldFox costs what it does. __ __
>>>>>>>>
>>>>>>>> It could be added to PC software pretty easily, not sure it would fit
in the firmware in the NanoVNA2 itself. __ __
>>>>>>>>
>>>>>>>> But while it’s just a few lines of code to implement, it does have a
“maintenance tail” __ __
>>>>>>>>
>>>>>>>> __ __
>>>>>>>>
>>>>>>>>
>
> __ __
>>>>>>>>
>>>>>>>>> On Mar 18, 2024, at 8:29 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>
>>>>>>>>> __ __
>>>>>>>>
>>>>>>>>> The Keysight Fieldfox has a PC program that will adjust the TCXO to
match a connected 10MHz reference. I will check my nanoVNA with a frequency
counter connected to a GPS reference. __ __
>>>>>>>>>
>>>>>>>>> __ __
>>>>>>>>>
>>>>>>>>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>
>>>>>>>>>> I’m tuning duplexers for ham 440 repeaters __ __
>>>>>>>>>>
>>>>>>>>>> Best regards, __ __
>>>>>>>>>>
>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>
>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>
>>>>>>>>>>
>
> __ __
>>>>>>>>>>
>>>>>>>>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>
>>>>>>>>>>> __ __
>>>>>>>>>>
>>>>>>>>>>> I am confused. Why do you need a diplexer for FM broadcast
transmission? Coupling two transmitters on different channels to a single
antenna? I usually associate diplexers with repeaters. __ __
>>>>>>>>>>>
>>>>>>>>>>> __ __
>>>>>>>>>>>
>>>>>>>>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>
>>>>>>>>>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20
ppm frequency tolerance is just fine. __ __
>>>>>>>>>>>>
>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>
>>>>>>>>>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> I thought the OP was tuning duplexes for amateur radio
repeaters. Ham FM uses 25 kHz channel spacing, most public service now uses
12.5 kHz spacing. NBFM deviation is narrower as is most digital (like P25 or
DMR). __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very
critical (the detector is insensitive to it). And licensing makes sure that
nobody else on your channel is anywhere close to near your power, so yeah,
capture effect. __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On AM you could get heterodynes, but just as with FM, your
license protects you from anyone close by. Aircraft use AM, and heterodynes
are a feature of life. __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Broadcast doesn’t use SSB (in general), which is where
frequency accuracy would be important, for “no need to use clarifier” on
speech. 20Hz (1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20
MHz) would be intolerable. __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> There are “simulbroadcast” on the same frequency in EU for TV
(and maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better. __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them? __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100
MHz, that’s 20 ppm, which is fairly loose. In practice, they probably are
better, but no guarantees. __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Same for AM - 20 ppm. __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> WWV would be better (but is kind of weak unless you live in
Ft. Collins or Kauai) __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Hi Bob, __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test. __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> < image0.jpeg> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> When I’ve time I will do the same test with my Keysight
Fieldfox. __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even
the best equipment drifts and the the crystal ages so require re-calibration.
I’ll try checking mine with a frequency counter using a GOS reference. __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Thanks Bob, __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Good advice! The best way to get around this would be to
use the repeater as a signal generator after tuning - will try that next one I
do. __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor?
Will check the spec. __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> It seems to me that your biggest concern would be with
frequency accuracy. No way to sinc the nanVNA with an external GPS
disciplined time base. You may tune the diplexer a few kHz off the desired
channel. __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Thanks Jim, __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Very detailed response! Fixturing in this case would
seem less relevant with duplexers? They’re solidly built with n connectors.
The actual attenuation in the stop band isn’t as important as being able to
accurately tune for the null. Using the earlier model nano VNAs there was no
way to reduce the bandwidth as in the Fieldfox. The pro version seems to allow
quite narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense! __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> High isolation measurements are often more fixture
limited than instrument limited. __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6
dB/bit for a 16 bit ADC. __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> The actual measurement SNR might be different - better,
because multiple ADC samples are averaged; worse, because a 16 bit ADC usually
has 13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc. __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like
that. You’d need a precise attenuator with 96 dB attenuation, for instance.
That’s no trivial matter. __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Usually what you do is measure a few signals at various
larger levels, and then assume (verify) linearity, and extrapolate down to
the noise floor. __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J ____
>>
>>> > > > > __
>>>
>>> <IMG_5049.JPG>
>>>
>>> <IMG_5048.JPG>
>>>
>>> <IMG_5046.JPG>
_._,_._,_
* * *
Hi Jim,
That’s very perceptive of you! However I’m not buying it as I just listened to
the VNA 440MHz output on an FT817 in SSB mode - nice clean heterodyne.
Best regards,
Rob Rowlands
415 849 5667
> On Mar 21, 2024, at 8:59 AM, Jim Lux <jimlux@earthlink.net> wrote:
>
>
> The one with every harmonic (not just odd) means that the output isn’t a
square wave, it’s pulses. The lower the duty cycle (i.e. narrower the pulses
relative to the period) the less quickly the harmonics fall off. In the limit
(an infinitely narrow pulse), the power spectrum is a series of impulses of
equal amplitude.
>
>
>
>
>
>
>
>
>
>
>
>
>
>> On Mar 20, 2024, at 9:33 PM, Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
>
>
>
>>
>>
>> Hi Bob,
>>
>>
>>
>> I did some harmonic analysis on the GPS Disciplined FieldFox of my two
NanoVNAs and also the Sig Gen output on my Tiny SA Ultra, with very
interesting results:
>>
>>
>>
>> 1. The NanoVNA-F V2 gave the expected integer multiples of 440MHz with
odd harmonics dominant
>
>>
>> <image003.jpg>
>>
>>
>
>
>> 2. The NanoVNA-H 4 unusually had non integer “harmonics”, suggesting it
generates its stimulus by heterodyning?
>
>
>> 3. <image004.jpg>
>>
>>
>>
>>
>>
>>
>>
>> My TinySA Ultra signal generator mode produced no visible harmonics and was
also very close to nominal 440MHz
>>
>>
>
>>
>> <image005.jpg>
>>
>> This is a detailed span at 2kHz, using the same setup I used on the Nano –
while its hard to believe Tiny SA sig gen appears to be only 40 Hz off nominal
. Just to be sure I checked that the Fieldfox GPS receiver is seeing 14
satellites.
>
>
>>
>> <image006.jpg>
>>
>> My bottom line on all this is that I needn’t worry about frequency accuracy
using these low cost RF tools to tune duplexers. Your opinion?
>>
>>
>>
>> 73,
>>
>>
>>
>> Rob
>>
>> 415 849 5667
>>
>>
>>
>> **From:** NanoVNAV2@groups.io <NanoVNAV2@groups.io> **On Behalf Of** Bob
W0EG
> **Sent:** Wednesday, March 20, 2024 7:48 AM
> **To:** NanoVNAV2@groups.io
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro
>>
>>
>>
>> Rob,
>>
>> Your VNA model is different from my nanoVNA V2 Plus four in that the "CW"
output on mine is a square wave and thus has infinite sidebands aand appears
as a very broad signal on my spectrum analyzer. However, the center frequency
does seem to be reasonably accurate. Attached photos show the signal in a 2
MHz span, one on auto and one on a slow one second sweep. Going to a 2 kHz
sweep like on your Field Fox gives a line across the top..
>>
>>
>>
>>
>>
>> On Wed, Mar 20, 2024 at 8:34 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>
>>> That looks really good. Perhaps my counter has difficulty with the nest
square wave output. I’ll try looking at it with a spectrum analyzer and an
oscilloscope.
>>>
>>>
>>>
>>> On Wed, Mar 20, 2024 at 6:00 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>
>>>> Hi Bob,
>>>>
>>>>
>>>>
>>>> I just tested the 440MHz CW output of my NanoVNA-H4 with the Fieldfox
sync’d to GPS.
>>>>
>>>>
>>>>
>>>> Attached is the FF Spectrum Analyzer plot with markers showing the Nano
output at 439.99924MHz. This would be 760Hz low, or 1.73ppm if my math is
correct. Not bad don’t you think? I used to work with stratum 3 telecom clocks
at 4.6ppm!
>>>>
>>>>
>>>>
>>>> I also looked at the frequency delta between the FieldFox internal clock
and GPS, and only saw about 100Hz. I would have expected your HP 5385 counter
to be better as it probably has an oven?
>>>>
>>>>
>>>>
>>>> Just for giggles I have ordered this OCXO from Amazon that should be
interesting – for $20 it might be useful.
[https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
Also ordered a $60 GPS disciplined source from Ali express
[https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa)
>>>>
>>>>
>>>>
>>>> Keeping time here..
>>>>
>>>>
>>>>
>>>> 73,
>>>>
>>>>
>>>>
>>>> Rob NZ6J
>>>>
>>>> 415 849 5667
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> **From:** [ NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
<[NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)> **On Behalf Of** Bob W0EG
> **Sent:** Tuesday, March 19, 2024 8:37 AM
> **To:** [ NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro
>>>>
>>>>
>>>>
>>>> I should note that the “CW” output from the nano is not a pure sine wave,
more of a rounded off square wave. So it is possible that the counter may
have issues with the signal. I try to have a look at it on a spectrum
analyzer also synced to the 10MHz reference. Also, when measuring a 10MHz
signal on this counter, removing the GPS reference only changed the reading by
twenty five Hz.
>>>>
>>>>
>>>>
>>>> On Tue, Mar 19, 2024 at 11:14 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>
>>>>> <image001.jpg>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Mar 19, 2024 at 10:11 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>
>>>>>> <image002.jpg>
>>>>>>
>>>>>> NanoVNA set to CW 440 MHz. Off by over 500kHz
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Tue, Mar 19, 2024 at 12:59 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>
>>>>>>> That kind of thing is why the FieldFox costs what it does.
>>>>>>>
>>>>>>> It could be added to PC software pretty easily, not sure it would fit
in the firmware in the NanoVNA2 itself.
>>>>>>>
>>>>>>> But while it’s just a few lines of code to implement, it does have a
“maintenance tail”
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> On Mar 18, 2024, at 8:29 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>> The Keysight Fieldfox has a PC program that will adjust the TCXO to
match a connected 10MHz reference. I will check my nanoVNA with a frequency
counter connected to a GPS reference.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>
>>>>>>>>> I’m tuning duplexers for ham 440 repeaters
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>>
>>>>>>>>> Rob Rowlands
>>>>>>>>>
>>>>>>>>> 415 849 5667
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> I am confused. Why do you need a diplexer for FM broadcast
transmission? Coupling two transmitters on different channels to a single
antenna? I usually associate diplexers with repeaters.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>>
>>>>>>>>>>> FM broadcast.. much wider deviation, and subcarriers too. So 20
ppm frequency tolerance is just fine.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> I thought the OP was tuning duplexes for amateur radio repeaters.
Ham FM uses 25 kHz channel spacing, most public service now uses 12.5 kHz
spacing. NBFM deviation is narrower as is most digital (like P25 or DMR).
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very
critical (the detector is insensitive to it). And licensing makes sure that
nobody else on your channel is anywhere close to near your power, so yeah,
capture effect.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On AM you could get heterodynes, but just as with FM, your
license protects you from anyone close by. Aircraft use AM, and heterodynes
are a feature of life.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Broadcast doesn’t use SSB (in general), which is where frequency
accuracy would be important, for “no need to use clarifier” on speech. 20Hz
(1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20 MHz) would be
intolerable.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> There are “simulbroadcast” on the same frequency in EU for TV
(and maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t hear
heterodynes, or does the fm capture effect suppress them?
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100 MHz,
that’s 20 ppm, which is fairly loose. In practice, they probably are better,
but no guarantees.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Same for AM - 20 ppm.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> WWV would be better (but is kind of weak unless you live in
Ft. Collins or Kauai)
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Hi Bob,
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Here’s a very rough comparison using tinySA ultra between a
NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> <image0.jpeg>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> When I’ve time I will do the same test with my Keysight
Fieldfox.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even the
best equipment drifts and the the crystal ages so require re-calibration.
I’ll try checking mine with a frequency counter using a GOS reference.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Thanks Bob,
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Good advice! The best way to get around this would be to
use the repeater as a signal generator after tuning - will try that next one I
do.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor?
Will check the spec.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> It seems to me that your biggest concern would be with
frequency accuracy. No way to sinc the nanVNA with an external GPS
disciplined time base. You may tune the diplexer a few kHz off the desired
channel.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Very detailed response! Fixturing in this case would
seem less relevant with duplexers? They’re solidly built with n connectors.
The actual attenuation in the stop band isn’t as important as being able to
accurately tune for the null. Using the earlier model nano VNAs there was no
way to reduce the bandwidth as in the Fieldfox. The pro version seems to allow
quite narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense!
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Rob Rowlands
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> 415 849 5667
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> High isolation measurements are often more fixture
limited than instrument limited.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6 dB/bit
for a 16 bit ADC.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> The actual measurement SNR might be different - better,
because multiple ADC samples are averaged; worse, because a 16 bit ADC usually
has 13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The actual
measurement performance of an ADC is affected by a bunch of things - clock
noise, sampler uncertainty, etc.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like
that. You’d need a precise attenuator with 96 dB attenuation, for instance.
That’s no trivial matter.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Usually what you do is measure a few signals at various
larger levels, and then assume (verify) linearity, and extrapolate down to
the noise floor.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J
_._,_._,_
* * *
Rob,
Can I ask you to do one more sweep? 440 MHz center with 2 MHz span. I am
thinking that the issue with my counter is not due to harmonics but rather
phase noise/jitter creating a broad , essentially modulated signal.
Perhaps the modulation is intended and aids the receiver. It could also be
that your nano VNA is different than mine.
On Fri, Mar 22, 2024 at 2:29 AM Rob Rowlands NZ6J <rowlands47@gmail.com>
wrote:
Hi Bob,
Happy to help.
Feel free to call if you’d like to chat?
Best regards,
Rob Rowlands
415 849 5667
> On Mar 22, 2024, at 9:59 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>
>
>
>
> Rob,
>
>
>
>
> Can I ask you to do one more sweep? 440 MHz center with 2 MHz span. I am
thinking that the issue with my counter is not due to harmonics but rather
phase noise/jitter creating a broad , essentially modulated signal. Perhaps
the modulation is intended and aids the receiver. It could also be that your
nano VNA is different than mine.
>
>
>
>
> On Fri, Mar 22, 2024 at 2:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>
>> Hi Bob,
>>
>>
>
>>
>> Here’s the wider plot showing 3rd harmonic down 23dB, not a square wave but
definitely not a pure sinewave. My understanding is VNAs have tunable receive
filters, so harmonic content of the generator isn't material.
>>
>>
>
>>
>> <image0.jpeg>
>>
>>
>
>>
>> Best regards,
>>
>> Rob Rowlands
>>
>> 415 849 5667
>>
>>
>
>>
>>> On Mar 21, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>
>>>
>>
>>> Rob,
>>>
>>>
>
>>>
>>> The clean signal in your photo sure looks like a sign wave. I don’t see
any side bands. Can you post a photo with a wider span? My nano seems
different. I would be surprised if a very expensive analyzer like the
Keysight Fieldfox had square wave outputs.
>>>
>>>
>
>>>
>>> On Thu, Mar 21, 2024 at 12:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>
>>>> Hi Bob,
>>>>
>>>>
>
>>>>
>>>> I’m sure all the NanoVNA models have square wave outputs, as does the
Fieldfox. My objective here was to look at the fundamental frequency on a gps
disciplined SA to see how far off frequency it was when set to 440MHz. The
existence of all the harmonics shouldn’t be a problem tuning a duplexer, but
could be with other DUTs.
>>>>
>>>>
>
>>>>
>>>> Best regards,
>>>>
>>>> Rob Rowlands
>>>>
>>>> 415 849 5667
>>>>
>>>>
>
>>>>
>>>>> On Mar 20, 2024, at 8:43 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>
>>>>
>>>>>
>>>>>
>>>>> Rob,
>>>>>
>>>>> Your VNA model is different from my nanoVNA V2 Plus four in that the
"CW" output on mine is a square wave and thus has infinite sidebands aand
appears as a very broad signal on my spectrum analyzer. However, the center
frequency does seem to be reasonably accurate. Attached photos show the
signal in a 2 MHz span, one on auto and one on a slow one second sweep. Going
to a 2 kHz sweep like on your Field Fox gives a line across the top..
>>>>>
>>>>>
>
>>>>>
>>>>>
>
>>>>>
>>>>> On Wed, Mar 20, 2024 at 8:34 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote:
>
>>>>>
>>>>>> That looks really good. Perhaps my counter has difficulty with the
nest square wave output. I’ll try looking at it with a spectrum analyzer and
an oscilloscope.
>>>>>>
>>>>>>
>
>>>>>>
>>>>>> On Wed, Mar 20, 2024 at 6:00 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote:
>
>>>>>>
>>>>>>> Hi Bob, __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> I just tested the 440MHz CW output of my NanoVNA-H4 with the Fieldfox
sync’d to GPS. __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> Attached is the FF Spectrum Analyzer plot with markers showing the
Nano output at 439.99924MHz. This would be 760Hz low, or 1.73ppm if my math is
correct. Not bad don’t you think? I used to work with stratum 3 telecom clocks
at 4.6ppm! __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> I also looked at the frequency delta between the FieldFox internal
clock and GPS, and only saw about 100Hz. I would have expected your HP 5385
counter to be better as it probably has an oven? __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> Just for giggles I have ordered this OCXO from Amazon that should be
interesting – for $20 it might be
useful.[https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
Also ordered a $60 GPS disciplined source from Ali express
[https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa)
__ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> Keeping time here.. __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> 73, __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> Rob NZ6J __ __
>>>>>>>
>>>>>>> 415 849 5667 __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> **From:** [NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
<[NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)> **On Behalf Of** Bob W0EG
> **Sent:** Tuesday, March 19, 2024 8:37 AM
> **To:** [NanoVNAV2@groups.io](mailto:NanoVNAV2@groups.io)
> **Subject:** Re: [nanovnav2] Tuning 440 duplexers with V2 Plus4 Pro __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> I should note that the “CW” output from the nano is not a pure sine
wave, more of a rounded off square wave. So it is possible that the counter
may have issues with the signal. I try to have a look at it on a spectrum
analyzer also synced to the 10MHz reference. Also, when measuring a 10MHz
signal on this counter, removing the GPS reference only changed the reading by
twenty five Hz. __ __
>>>>>>>
>>>>>>> __ __
>>>>>>>
>>>>>>> On Tue, Mar 19, 2024 at 11:14 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>
>>>>>>>> < image001.jpg>
>>>>>>>>
>>>>>>>> __ __
>>>>>>>>
>>>>>>>> __ __
>>>>>>>>
>>>>>>>> __ __
>>>>>>>>
>>>>>>>> On Tue, Mar 19, 2024 at 10:11 AM Bob Morris
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>
>>>>>>>>> < image002.jpg>
>>>>>>>>>
>>>>>>>>> __ __
>>>>
>>>>> > > > > NanoVNA set to CW 440 MHz. Off by over 500kHz __ __
>>>>
>>>>> > > > > > > > > > __ __
>>>>>>>>>
>>>>>>>>> On Tue, Mar 19, 2024 at 12:59 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>
>>>>>>>>>> That kind of thing is why the FieldFox costs what it does. __ __
>>>>>>>>>>
>>>>>>>>>> It could be added to PC software pretty easily, not sure it would
fit in the firmware in the NanoVNA2 itself. __ __
>>>>>>>>>>
>>>>>>>>>> But while it’s just a few lines of code to implement, it does have
a “maintenance tail” __ __
>>>>>>>>>>
>>>>>>>>>> __ __
>>>>>>>>>>
>>>>>>>>>>
>
> __ __
>>>>>>>>>>
>>>>>>>>>>> On Mar 18, 2024, at 8:29 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>
>>>>>>>>>>> __ __
>>>>>>>>>>
>>>>>>>>>>> The Keysight Fieldfox has a PC program that will adjust the TCXO
to match a connected 10MHz reference. I will check my nanoVNA with a
frequency counter connected to a GPS reference. __ __
>>>>>>>>>>>
>>>>>>>>>>> __ __
>>>>>>>>>>>
>>>>>>>>>>> On Mon, Mar 18, 2024 at 4:29 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>
>>>>>>>>>>>> I’m tuning duplexers for ham 440 repeaters __ __
>>>>>>>>>>>>
>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>
>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>
>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>
>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>
>>>>>>>>>>>>> On Mar 17, 2024, at 11:28 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>
>>>>>>>>>>>>> I am confused. Why do you need a diplexer for FM broadcast
transmission? Coupling two transmitters on different channels to a single
antenna? I usually associate diplexers with repeaters. __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Sun, Mar 17, 2024 at 2:28 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>
>>>>>>>>>>>>>> FM broadcast.. much wider deviation, and subcarriers too. So
20 ppm frequency tolerance is just fine. __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mar 16, 2024, at 9:30 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> I thought the OP was tuning duplexes for amateur radio
repeaters. Ham FM uses 25 kHz channel spacing, most public service now uses
12.5 kHz spacing. NBFM deviation is narrower as is most digital (like P25 or
DMR). __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Sat, Mar 16, 2024 at 12:58 AM Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> FM has 100 kHz deviation, so the center frequency isn’t very
critical (the detector is insensitive to it). And licensing makes sure that
nobody else on your channel is anywhere close to near your power, so yeah,
capture effect. __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On AM you could get heterodynes, but just as with FM, your
license protects you from anyone close by. Aircraft use AM, and heterodynes
are a feature of life. __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Broadcast doesn’t use SSB (in general), which is where
frequency accuracy would be important, for “no need to use clarifier” on
speech. 20Hz (1ppm at 20 MHz) is good enough for that. 20 ppm (400 Hz at 20
MHz) would be intolerable. __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> There are “simulbroadcast” on the same frequency in EU for TV
(and maybe FM), all transmitting the same signal, and for that, the frequency
control has to be much better. __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Mar 15, 2024, at 10:40 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I’m amazed that 20 ppm is acceptable! How come we don’t
hear heterodynes, or does the fm capture effect suppress them? __ __
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Mar 15, 2024, at 8:59 AM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> In the US, FM broadcast has to be within 2000 Hz. At 100
MHz, that’s 20 ppm, which is fairly loose. In practice, they probably are
better, but no guarantees. __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Same for AM - 20 ppm. __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> <https://www.law.cornell.edu/cfr/text/47/73.1545> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> WWV would be better (but is kind of weak unless you live in
Ft. Collins or Kauai) __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On Mar 14, 2024, at 9:58 PM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Hi Bob, __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Here’s a very rough comparison using tinySA ultra between
a NanoVNA-F V2 by SeeSii radiating at c. 88.5MHz compared with a previously
measured carrier marker from our NPR station with no modulation. The delta of
577Hz is pretty good for cheap kit don’t you think? I don’t have a V2 Plus 4
pro yet to test. __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> < image0.jpeg> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> When I’ve time I will do the same test with my Keysight
Fieldfox. __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Mar 14, 2024, at 8:59 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Don’t know but it does not have a TCXO or an oven. Even
the best equipment drifts and the the crystal ages so require re-calibration.
I’ll try checking mine with a frequency counter using a GOS reference. __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Thu, Mar 14, 2024 at 1:30 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Thanks Bob, __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Good advice! The best way to get around this would be to
use the repeater as a signal generator after tuning - will try that next one I
do. __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Do you think the v2plus pro frequency accuracy is poor?
Will check the spec. __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On Mar 13, 2024, at 9:12 AM, Bob W0EG
<[morrisnc7@gmail.com](mailto:morrisnc7@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> It seems to me that your biggest concern would be with
frequency accuracy. No way to sinc the nanVNA with an external GPS
disciplined time base. You may tune the diplexer a few kHz off the desired
channel. __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On Wed, Mar 13, 2024 at 11:59 AM Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Thanks Jim, __ __
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Very detailed response! Fixturing in this case would
seem less relevant with duplexers? They’re solidly built with n connectors.
The actual attenuation in the stop band isn’t as important as being able to
accurately tune for the null. Using the earlier model nano VNAs there was no
way to reduce the bandwidth as in the Fieldfox. The pro version seems to allow
quite narrow bandwidth. Noise is still an issue I found too, so being able to
transmit the maximum power is important. Poor stop band attenuation means
desense! __ __
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Best regards, __ __
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Rob Rowlands __ __
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> 415 849 5667 __ __
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 9:59 PM, Jim Lux
<[jimlux@earthlink.net](mailto:jimlux@earthlink.net)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> High isolation measurements are often more fixture
limited than instrument limited. __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> I suspect, though, that the 96 dB happens to be 6
dB/bit for a 16 bit ADC. __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> The actual measurement SNR might be different -
better, because multiple ADC samples are averaged; worse, because a 16 bit ADC
usually has 13-14 bit ENOB (Effective number of bits) or 70-80 dB SNR. The
actual measurement performance of an ADC is affected by a bunch of things -
clock noise, sampler uncertainty, etc. __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> I would be challenging to verify a dynamic range like
that. You’d need a precise attenuator with 96 dB attenuation, for instance.
That’s no trivial matter. __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Usually what you do is measure a few signals at
various larger levels, and then assume (verify) linearity, and extrapolate
down to the noise floor. __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>
> __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> On Mar 12, 2024, at 8:03 AM, Rob Rowlands NZ6J
<[rowlands47@gmail.com](mailto:rowlands47@gmail.com)> wrote: __ __
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>
> Ive been tuning 440 duplexers with a Keysight Fieldfox to about 80dB
isolation. The banner spec for the pro shows 96dB dynamic range but wonder of
the pro will allows tuning isolation values close to that?
>
> Rob NZ6J ____
>>>>
>>>>> > > > > __
>>>>>
>>>>> <IMG_5049.JPG>
>>>>>
>>>>> <IMG_5048.JPG>
>>>>>
>>>>> <IMG_5046.JPG>
>>
>>> _._,_._,_
* * *
1.) A square or any distorted waveform generates harmonics of the
fundamental frequency. If that is 200 MHz then the lowest harmonic is
400 MHz. Square waves contain odd harmonics, like 600 (3rd) and 1000
(5th) MHz and higher in this example of 200 MHz. This isn't saying other
multiples cannot be present.
2.) A pulsed waveform or any amplitude or frequency modulated signal has
to generate sidebands adjacent to the carrier. It does not cause
harmonics. The bandwidth or spacing and level of sidebands depends on
the rate and amount the frequency or level changes. Frequency jitter
would fall in this class.
3.) Noise is just noise.
Even a very good cavity duplexer is in the MHz wide range on 440 MHz. A
measurement within a several tens of kilohertz on 440 MHz is more than
good enough. It isn't like we are sweeping mechanical resonators of some
type. They are just stubs and cavities.
I should measure my Nano VNAs. I have a few of them someplace.
73 Tom
On 3/22/2024 10:56 AM, Bob W0EG wrote:
> Rob,
>
> Can I ask you to do one more sweep? 440 MHz center with 2 MHz span.
> I am thinking that the issue with my counter is not due to harmonics
> but rather phase noise/jitter creating a broad , essentially modulated
> signal. Perhaps the modulation is intended and aids the receiver. It
> could also be that your nano VNA is different than mine.
>
> On Fri, Mar 22, 2024 at 2:29 AM Rob Rowlands NZ6J
> <rowlands47@gmail.com> wrote:
>
> Hi Bob,
>
> Here’s the wider plot showing 3rd harmonic down 23dB, not a square
> wave but definitely not a pure sinewave. My understanding is VNAs
> have tunable receive filters, so harmonic content of the generator
> isn't material.
>
> image0.jpeg
> Best regards,
> Rob Rowlands
> 415 849 5667
>
>> On Mar 21, 2024, at 8:59 AM, Bob W0EG <morrisnc7@gmail.com> wrote:
>>
>>
>> Rob,
>>
>> The clean signal in your photo sure looks like a sign wave. I
>> don’t see any side bands. Can you post a photo with a wider
>> span? My nano seems different. I would be surprised if a very
>> expensive analyzer like the Keysight Fieldfox had square wave
>> outputs.
>>
>> On Thu, Mar 21, 2024 at 12:29 AM Rob Rowlands NZ6J
>> <rowlands47@gmail.com> wrote:
>>
>> Hi Bob,
>>
>> I’m sure all the NanoVNA models have square wave outputs, as
>> does the Fieldfox. My objective here was to look at the
>> fundamental frequency on a gps disciplined SA to see how far
>> off frequency it was when set to 440MHz. The existence of all
>> the harmonics shouldn’t be a problem tuning a duplexer, but
>> could be with other DUTs.
>>
>> Best regards,
>> Rob Rowlands
>> 415 849 5667
>>
>>> On Mar 20, 2024, at 8:43 AM, Bob W0EG <morrisnc7@gmail.com>
>>> wrote:
>>>
>>>
>>> Rob,
>>> Your VNA model is different from my nanoVNA V2 Plus four in
>>> that the "CW" output on mine is a square wave and thus has
>>> infinite sidebands aand appears as a very broad signal on my
>>> spectrum analyzer. However, the center frequency does seem
>>> to be reasonably accurate. Attached photos show the signal
>>> in a 2 MHz span, one on auto and one on a slow one second
>>> sweep. Going to a 2 kHz sweep like on your Field Fox gives
>>> a line across the top..
>>>
>>>
>>> On Wed, Mar 20, 2024 at 8:34 AM Bob Morris
>>> <morrisnc7@gmail.com> wrote:
>>>
>>> That looks really good. Perhaps my counter has
>>> difficulty with the nest square wave output. I’ll try
>>> looking at it with a spectrum analyzer and an oscilloscope.
>>>
>>> On Wed, Mar 20, 2024 at 6:00 AM Rob Rowlands NZ6J
>>> <rowlands47@gmail.com> wrote:
>>>
>>> Hi Bob,
>>>
>>> I just tested the 440MHz CW output of my NanoVNA-H4
>>> with the Fieldfox sync’d to GPS.
>>>
>>> Attached is the FF Spectrum Analyzer plot with
>>> markers showing the Nano output at 439.99924MHz.
>>> This would be 760Hz low, or 1.73ppm if my math is
>>> correct. Not bad don’t you think? I used to work
>>> with stratum 3 telecom clocks at 4.6ppm!
>>>
>>> I also looked at the frequency delta between the
>>> FieldFox internal clock and GPS, and only saw about
>>> 100Hz. I would have expected your HP 5385 counter to
>>> be better as it probably has an oven?
>>>
>>> Just for giggles I have ordered this OCXO from
>>> Amazon that should be interesting – for $20 it might
>>> be useful.
>>> https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
>>> <https://www.amazon.com/gp/product/B0B5VJK7HJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1>
>>> Also ordered a $60 GPS disciplined source from Ali
>>> express
>>> https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa
>>> <https://www.aliexpress.us/item/3256806208168433.html?spm=a2g0o.order_detail.order_detail_item.3.255df19cxOVvgu&gatewayAdapt=glo2usa>
>>>
>>> Keeping time here..
>>>
>>> 73,
>>>
>>> Rob NZ6J
>>>
>>> 415 849 5667
>>>
>>> *From:*NanoVNAV2@groups.io <NanoVNAV2@groups.io> *On
>>> Behalf Of *Bob W0EG
>>> *Sent:* Tuesday, March 19, 2024 8:37 AM
>>> *To:* NanoVNAV2@groups.io
>>> *Subject:* Re: [nanovnav2] Tuning 440 duplexers with
>>> V2 Plus4 Pro
>>>
>>> I should note that the “CW” output from the nano is
>>> not a pure sine wave, more of a rounded off square
>>> wave. So it is possible that the counter may have
>>> issues with the signal. I try to have a look at it
>>> on a spectrum analyzer also synced to the 10MHz
>>> reference. Also, when measuring a 10MHz signal on
>>> this counter, removing the GPS reference only
>>> changed the reading by twenty five Hz.
>>>
>>> On Tue, Mar 19, 2024 at 11:14 AM Bob Morris
>>> <morrisnc7@gmail.com> wrote:
>>>
>>> <image001.jpg>
>>>
>>> On Tue, Mar 19, 2024 at 10:11 AM Bob Morris
>>> <morrisnc7@gmail.com> wrote:
>>>
>>> <image002.jpg>
>>>
>>> NanoVNA set to CW 440 MHz. Off by over 500kHz
>>>
>>> On Tue, Mar 19, 2024 at 12:59 AM Jim Lux
>>> <jimlux@earthlink.net> wrote:
>>>
>>> That kind of thing is why the FieldFox
>>> costs what it does.
>>>
>>> It could be added to PC software pretty
>>> easily, not sure it would fit in the
>>> firmware in the NanoVNA2 itself.
>>>
>>> But while it’s just a few lines of code
>>> to implement, it does have a
>>> “maintenance tail”
>>>
>>>
>>>
>>> On Mar 18, 2024, at 8:29 AM, Bob
>>> W0EG <morrisnc7@gmail.com> wrote:
>>>
>>>
>>>
>>> The Keysight Fieldfox has a PC
>>> program that will adjust the TCXO to
>>> match a connected 10MHz reference.
>>> I will check my nanoVNA with a
>>> frequency counter connected to a GPS
>>> reference.
>>>
>>> On Mon, Mar 18, 2024 at 4:29 AM Rob
>>> Rowlands NZ6J <rowlands47@gmail.com>
>>> wrote:
>>>
>>> I’m tuning duplexers for ham 440
>>> repeaters
>>>
>>> Best regards,
>>>
>>> Rob Rowlands
>>>
>>> 415 849 5667
>>>
>>>
>>>
>>> On Mar 17, 2024, at
>>> 11:28 AM, Bob W0EG
>>> <morrisnc7@gmail.com> wrote:
>>>
>>>
>>>
>>> I am confused. Why do you
>>> need a diplexer for FM
>>> broadcast transmission?
>>> Coupling two transmitters on
>>> different channels to a
>>> single antenna? I usually
>>> associate diplexers with
>>> repeaters.
>>>
>>> On Sun, Mar 17, 2024 at 2:28
>>> AM Jim Lux
>>> <jimlux@earthlink.net> wrote:
>>>
>>> FM broadcast.. much
>>> wider deviation, and
>>> subcarriers too. So 20
>>> ppm frequency tolerance
>>> is just fine.
>>>
>>>
>>>
>>> On Mar 16, 2024, at
>>> 9:30 AM, Bob W0EG
>>> <morrisnc7@gmail.com>
>>> wrote:
>>>
>>>
>>>
>>> I thought the OP was
>>> tuning duplexes for
>>> amateur radio
>>> repeaters. Ham FM
>>> uses 25 kHz channel
>>> spacing, most public
>>> service now uses
>>> 12.5 kHz spacing.
>>> NBFM deviation is
>>> narrower as is most
>>> digital (like P25 or
>>> DMR).
>>>
>>> On Sat, Mar 16, 2024
>>> at 12:58 AM Jim Lux
>>> <jimlux@earthlink.net>
>>> wrote:
>>>
>>> FM has 100 kHz
>>> deviation, so
>>> the center
>>> frequency isn’t
>>> very critical
>>> (the detector is
>>> insensitive to
>>> it). And
>>> licensing makes
>>> sure that nobody
>>> else on your
>>> channel is
>>> anywhere close
>>> to near your
>>> power, so yeah,
>>> capture effect.
>>>
>>> On AM you could
>>> get heterodynes,
>>> but just as with
>>> FM, your license
>>> protects you
>>> from anyone
>>> close by.
>>> Aircraft use AM,
>>> and heterodynes
>>> are a feature of
>>> life.
>>>
>>> Broadcast
>>> doesn’t use SSB
>>> (in general),
>>> which is where
>>> frequency
>>> accuracy would
>>> be important,
>>> for “no need to
>>> use clarifier”
>>> on speech. 20Hz
>>> (1ppm at 20 MHz)
>>> is good enough
>>> for that. 20 ppm
>>> (400 Hz at 20
>>> MHz) would be
>>> intolerable.
>>>
>>> There are
>>> “simulbroadcast”
>>> on the same
>>> frequency in EU
>>> for TV (and
>>> maybe FM), all
>>> transmitting the
>>> same signal, and
>>> for that, the
>>> frequency
>>> control has to
>>> be much better.
>>>
>>>
>>>
>>> On Mar 15,
>>> 2024, at
>>> 10:40 AM,
>>> Rob Rowlands
>>> NZ6J
>>> <rowlands47@gmail.com>
>>> wrote:
>>>
>>> I’m amazed
>>> that 20 ppm
>>> is
>>> acceptable!
>>> How come we
>>> don’t hear
>>> heterodynes,
>>> or does the
>>> fm capture
>>> effect
>>> suppress them?
>>>
>>> Best regards,
>>>
>>> Rob Rowlands
>>>
>>> 415 849 5667
>>>
>>>
>>>
>>> On Mar
>>> 15,
>>> 2024, at
>>> 8:59 AM,
>>> Jim Lux
>>> <jimlux@earthlink.net>
>>> wrote:
>>>
>>> In the
>>> US, FM
>>> broadcast
>>> has to
>>> be
>>> within
>>> 2000 Hz.
>>> At 100
>>> MHz,
>>> that’s
>>> 20 ppm,
>>> which is
>>> fairly
>>> loose.
>>> In
>>> practice,
>>> they
>>> probably
>>> are
>>> better,
>>> but no
>>> guarantees.
>>>
>>> Same for
>>> AM - 20 ppm.
>>>
>>> https://www.law.cornell.edu/cfr/text/47/73.1545
>>>
>>> WWV
>>> would be
>>> better
>>> (but is
>>> kind of
>>> weak
>>> unless
>>> you live
>>> in Ft.
>>> Collins
>>> or Kauai)
>>>
>>>
>>>
>>> On
>>> Mar
>>> 14,
>>> 2024,
>>> at
>>> 9:58 PM,
>>> Rob
>>> Rowlands
>>> NZ6J
>>> <rowlands47@gmail.com>
>>> wrote:
>>>
>>> Hi Bob,
>>>
>>> Here’s
>>> a
>>> very
>>> rough
>>> comparison
>>> using
>>> tinySA
>>> ultra
>>> between
>>> a
>>> NanoVNA-F
>>> V2
>>> by
>>> SeeSii
>>> radiating
>>> at
>>> c.
>>> 88.5MHz
>>> compared
>>> with
>>> a
>>> previously
>>> measured
>>> carrier
>>> marker
>>> from
>>> our
>>> NPR
>>> station
>>> with
>>> no
>>> modulation.
>>> The
>>> delta
>>> of
>>> 577Hz
>>> is
>>> pretty
>>> good
>>> for
>>> cheap
>>> kit
>>> don’t
>>> you
>>> think?
>>> I
>>> don’t
>>> have
>>> a V2
>>> Plus
>>> 4
>>> pro
>>> yet
>>> to test.
>>>
>>> <image0.jpeg>
>>>
>>> When
>>> I’ve
>>> time
>>> I
>>> will
>>> do
>>> the
>>> same
>>> test
>>> with
>>> my
>>> Keysight
>>> Fieldfox.
>>>
>>> Best
>>> regards,
>>>
>>> Rob
>>> Rowlands
>>>
>>> 415
>>> 849 5667
>>>
>>>
>>>
>>> On
>>> Mar
>>> 14,
>>> 2024,
>>> at
>>> 8:59 AM,
>>> Bob
>>> W0EG
>>> <morrisnc7@gmail.com>
>>> wrote:
>>>
>>>
>>>
>>> Don’t
>>> know
>>> but
>>> it
>>> does
>>> not
>>> have
>>> a
>>> TCXO
>>> or
>>> an
>>> oven.
>>> Even
>>> the
>>> best
>>> equipment
>>> drifts
>>> and
>>> the
>>> the
>>> crystal
>>> ages
>>> so
>>> require
>>> re-calibration.
>>> I’ll
>>> try
>>> checking
>>> mine
>>> with
>>> a
>>> frequency
>>> counter
>>> using
>>> a
>>> GOS
>>> reference.
>>>
>>> On
>>> Thu,
>>> Mar
>>> 14,
>>> 2024
>>> at
>>> 1:30
>>> AM
>>> Rob
>>> Rowlands
>>> NZ6J
>>> <rowlands47@gmail.com>
>>> wrote:
>>>
>>> Thanks
>>> Bob,
>>>
>>> Good
>>> advice!
>>> The
>>> best
>>> way
>>> to
>>> get
>>> around
>>> this
>>> would
>>> be
>>> to
>>> use
>>> the
>>> repeater
>>> as
>>> a
>>> signal
>>> generator
>>> after
>>> tuning
>>> -
>>> will
>>> try
>>> that
>>> next
>>> one
>>> I
>>> do.
>>>
>>>
>>> Do
>>> you
>>> think
>>> the
>>> v2plus
>>> pro
>>> frequency
>>> accuracy
>>> is
>>> poor?
>>> Will
>>> check
>>> the
>>> spec.
>>>
>>> Best
>>> regards,
>>>
>>> Rob
>>> Rowlands
>>>
>>> 415
>>> 849
>>> 5667
>>>
>>>
>>>
>>> On
>>> Mar
>>> 13,
>>> 2024,
>>> at
>>> 9:12 AM,
>>> Bob
>>> W0EG
>>> <morrisnc7@gmail.com>
>>> wrote:
>>>
>>>
>>>
>>> It
>>> seems
>>> to
>>> me
>>> that
>>> your
>>> biggest
>>> concern
>>> would
>>> be
>>> with
>>> frequency
>>> accuracy.
>>> No
>>> way
>>> to
>>> sinc the
>>> nanVNA
>>> with
>>> an
>>> external
>>> GPS
>>> disciplined time
>>> base.
>>> You
>>> may
>>> tune
>>> the
>>> diplexer
>>> a
>>> few
>>> kHz
>>> off
>>> the
>>> desired
>>> channel.
>>>
>>> On
>>> Wed,
>>> Mar
>>> 13,
>>> 2024
>>> at
>>> 11:59 AM
>>> Rob
>>> Rowlands
>>> NZ6J
>>> <rowlands47@gmail.com>
>>> wrote:
>>>
>>> Thanks
>>> Jim,
>>>
>>> Very
>>> detailed
>>> response!
>>> Fixturing
>>> in
>>> this
>>> case
>>> would
>>> seem
>>> less
>>> relevant
>>> with
>>> duplexers?
>>> They’re
>>> solidly
>>> built
>>> with
>>> n
>>> connectors.
>>> The
>>> actual
>>> attenuation
>>> in
>>> the
>>> stop
>>> band
>>> isn’t
>>> as
>>> important
>>> as
>>> being
>>> able
>>> to
>>> accurately
>>> tune
>>> for
>>> the
>>> null.
>>> Using
>>> the
>>> earlier
>>> model
>>> nano
>>> VNAs
>>> there
>>> was
>>> no
>>> way
>>> to
>>> reduce
>>> the
>>> bandwidth
>>> as
>>> in
>>> the
>>> Fieldfox.
>>> The
>>> pro
>>> version
>>> seems
>>> to
>>> allow
>>> quite
>>> narrow
>>> bandwidth.
>>> Noise
>>> is
>>> still
>>> an
>>> issue
>>> I
>>> found
>>> too,
>>> so
>>> being
>>> able
>>> to
>>> transmit
>>> the
>>> maximum
>>> power
>>> is
>>> important.
>>> Poor
>>> stop
>>> band
>>> attenuation
>>> means
>>> desense!
>>>
>>> Best
>>> regards,
>>>
>>> Rob
>>> Rowlands
>>>
>>> 415
>>> 849
>>> 5667
>>>
>>>
>>>
>>> On
>>> Mar
>>> 12,
>>> 2024,
>>> at
>>> 9:59 PM,
>>> Jim
>>> Lux
>>> <jimlux@earthlink.net>
>>> wrote:
>>>
>>> High
>>> isolation
>>> measurements
>>> are
>>> often
>>> more
>>> fixture
>>> limited
>>> than
>>> instrument
>>> limited.
>>>
>>> I
>>> suspect,
>>> though,
>>> that
>>> the
>>> 96
>>> dB
>>> happens
>>> to
>>> be
>>> 6
>>> dB/bit
>>> for
>>> a
>>> 16
>>> bit
>>> ADC.
>>>
>>> The
>>> actual
>>> measurement
>>> SNR
>>> might
>>> be
>>> different
>>> -
>>> better,
>>> because
>>> multiple
>>> ADC
>>> samples
>>> are
>>> averaged;
>>> worse,
>>> because
>>> a
>>> 16
>>> bit
>>> ADC
>>> usually
>>> has
>>> 13-14
>>> bit
>>> ENOB
>>> (Effective
>>> number
>>> of
>>> bits)
>>> or
>>> 70-80
>>> dB
>>> SNR.
>>> The
>>> actual
>>> measurement
>>> performance
>>> of
>>> an
>>> ADC
>>> is
>>> affected
>>> by
>>> a
>>> bunch
>>> of
>>> things
>>> -
>>> clock
>>> noise,
>>> sampler
>>> uncertainty,
>>> etc.
>>>
>>> I
>>> would
>>> be
>>> challenging
>>> to
>>> verify
>>> a
>>> dynamic
>>> range
>>> like
>>> that.
>>> You’d
>>> need
>>> a
>>> precise
>>> attenuator
>>> with
>>> 96
>>> dB
>>> attenuation,
>>> for
>>> instance.
>>> That’s
>>> no
>>> trivial
>>> matter.
>>>
>>>
>>> Usually
>>> what
>>> you
>>> do
>>> is
>>> measure
>>> a
>>> few
>>> signals
>>> at
>>> various
>>> larger
>>> levels,
>>> and
>>> then
>>> assume
>>> (verify)
>>> linearity,
>>> and
>>> extrapolate
>>> down
>>> to
>>> the
>>> noise
>>> floor.
>>>
>>>
>>>
>>> On
>>> Mar
>>> 12,
>>> 2024,
>>> at
>>> 8:03 AM,
>>> Rob
>>> Rowlands
>>> NZ6J
>>> <rowlands47@gmail.com>
>>> wrote:
>>>
>>> Hi,
>>>
>>> Ive
>>> been
>>> tuning
>>> 440
>>> duplexers
>>> with
>>> a
>>> Keysight
>>> Fieldfox
>>> to
>>> about
>>> 80dB
>>> isolation.
>>> The
>>> banner
>>> spec
>>> for
>>> the
>>> pro
>>> shows
>>> 96dB
>>> dynamic
>>> range
>>> but
>>> wonder
>>> of
>>> the
>>> pro
>>> will
>>> allows
>>> tuning
>>> isolation
>>> values
>>> close
>>> to
>>> that?
>>>
>>> Rob
>>> NZ6J
>>>
>>>
>>> <IMG_5049.JPG>
>>> <IMG_5048.JPG>
>>> <IMG_5046.JPG>
>>
>
--
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www.avg.com
I received my new Nano from China, and it looks good!
This is S21 of the stop band of a cheap 10MHz offset duplexer I bought to play with - not in 440 band.
As you can see the 90odd dB of dynamic range seems to be measurable. The app I am using (VNA View) has no smoothing.
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