Had to re-send, groups.io didn't recognize the address I used:

> I have been following the discussion of the output of this device with interest. Here are some captures from my SA that I would appreciate comments on.
> All show CW output set to 400 mHz.
>
> First, the harmonics to 3 gHz, this has been well commented on:
> [NANO Harm.png]
>
> Next, an attempt to view the fundamental from 30,000 feet so to speak, looks nice!
> [Nano 50 mHz RBW 300 Hz.png]
>
> Next, I was interested in a closer examination. Here is 2.5 mHz with RBW of 10 Hz:
>
> [NANO 2.50 mHz RBW 10 Hz.png]
>
> This starts to look very messy to me, aliasing or something going on, so onward we go.
>
> Here is 1mHz with RBW of 10 Hz. This plot is stable and does not change down to 1 Hz RBW:
>
> [NANO 1 mHz RBW 10 Hz.png]
>
> Still some strange stuff that looks like aliasing, but the lack of a clean fundamental is interesting. Onward we go.
>
> Next is a span of 125 kHz with resolution bandwidth of 3 Hz:
>
> [NANO 125 kHz RBO 3 Hz.jpg]
>
> This trace is stable and I imagine it to show the actual output of the digital oscillator chip. I just read in QST this morning (Local Oscillators for Transverters, by Paul Wade W1GHZ) that "In fractional-N mode, when the frequency cannot be divided by an integer, the chip switches rapidly between two integer ratios and averages them to the desired frequency". Is this what I am seeing? I am not an engineer, just an enthusiastic amateur (pun intended).
>
> JJ W0FAA
>
> PRIVILEGED AND CONFIDENTIAL DOCUMENT in accordance with Tenn. Code Ann. §§ 68-11-272 and 63-1-150.
> This E-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended only for the use of the Individual(s) named. If you are not the intended recipient of this E-mail, you are hereby notified that any dissemination or copying of this E-mail is strictly prohibited. Unencrypted email may be stored in plain text on many servers. Sensitive information should not be sent in this manner.
>
> Sent with [Proton Mail](https://pr.tn/ref/NV8FZHYH5PG0) secure email.

If your SA is an FFT unit and not a scanning SA (the original and older
designs), these may be due to aliasing. At HP, Tektronix loaned us one of
their earlier FFT SAs. It was pretty good on unmodulated signals - CW- ,
but anything with modulation, even mild digital modulation, it aliased
badly, especially at smaller RBWs. They have certainly improved, but I
still see aliasing on some digitally modulated signals.

BTW: mHz = milliHertz MHz = megaHertz

Dave - WØLEV

On Sun, Mar 24, 2024 at 4:59 AM W0FAA - JJ via groups.io <W0FAA=
protonmail.com@groups.io> wrote:

> Had to re-send, groups.io didn't recognize the address I used:
>
> I have been following the discussion of the output of this device with
> interest. Here are some captures from my SA that I would appreciate
> comments on.
> All show CW output set to 400 mHz.
>
> First, the harmonics to 3 gHz, this has been well commented on:
> [image: NANO Harm.png]
>
> Next, an attempt to view the fundamental from 30,000 feet so to speak,
> looks nice!
> [image: Nano 50 mHz RBW 300 Hz.png]
>
> Next, I was interested in a closer examination. Here is 2.5 mHz with RBW
> of 10 Hz:
>
> [image: NANO 2.50 mHz RBW 10 Hz.png]
> This starts to look very messy to me, aliasing or something going on, so
> onward we go.
>
> Here is 1mHz with RBW of 10 Hz. This plot is stable and does not change
> down to 1 Hz RBW:
>
> [image: NANO 1 mHz RBW 10 Hz.png]
>
> Still some strange stuff that looks like aliasing, but the lack of a clean
> fundamental is interesting. Onward we go.
>
> Next is a span of 125 kHz with resolution bandwidth of 3 Hz:
>
> [image: NANO 125 kHz RBO 3 Hz.jpg]
>
> This trace is stable and I imagine it to show the actual output of the
> digital oscillator chip. I just read in QST this morning (Local Oscillators
> for Transverters, by Paul Wade W1GHZ) that "In fractional-N mode, when the
> frequency cannot be divided by an integer, the chip switches rapidly
> between two integer ratios and averages them to the desired frequency". Is
> this what I am seeing? I am not an engineer, just an enthusiastic amateur
> (pun intended).
>
> JJ W0FAA
>
>
> PRIVILEGED AND CONFIDENTIAL DOCUMENT in accordance with Tenn. Code Ann. §§
> 68-11-272 and 63-1-150.
> This E-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended only
> for the use of the Individual(s) named. If you are not the intended
> recipient of this E-mail, you are hereby notified that any dissemination or
> copying of this E-mail is strictly prohibited. Unencrypted email may be
> stored in plain text on many servers. Sensitive information should not be
> sent in this manner.
>
> Sent with Proton Mail <https://pr.tn/ref/NV8FZHYH5PG0> secure email.
>
>
>
>
>

--

*Dave - WØLEV*

JJ W0FAA - Thank you for making these measurements and posting, much
appreciated. The results are not surprising; it looks to me like
modulation of the carrier by about 1 kHz with odd harmonics. This is
likely why my counter had difficulty making an accurate measurement. My
old HP spectrum analyzer only goes down to 3 kHz RBW so it’s past time for
an upgrade. The frequency accuracy is better than I expected.

This is not to in any way disparage the nanoVNA V2 Plus4, it is a fantastic
instrument considering the price. Very clever design and well suited for
measuring and adjusting linear, passive devices, such as filters and
duplexers, attenuators, directional couplers, power dividers, etc. It may
give unexpected results with some active devices such as amplifiers.

I hope that the designers can post here and add some clarity.


Bob W0EG

On Sun, Mar 24, 2024 at 12:59 AM W0FAA - JJ via groups.io <W0FAA=
protonmail.com@groups.io> wrote:

> Had to re-send, groups.io didn't recognize the address I used:
>
> I have been following the discussion of the output of this device with
> interest. Here are some captures from my SA that I would appreciate
> comments on.
> All show CW output set to 400 mHz.
>
> First, the harmonics to 3 gHz, this has been well commented on:
> [image: NANO Harm.png]
>
> Next, an attempt to view the fundamental from 30,000 feet so to speak,
> looks nice!
> [image: Nano 50 mHz RBW 300 Hz.png]
>
> Next, I was interested in a closer examination. Here is 2.5 mHz with RBW
> of 10 Hz:
>
> [image: NANO 2.50 mHz RBW 10 Hz.png]
> This starts to look very messy to me, aliasing or something going on, so
> onward we go.
>
> Here is 1mHz with RBW of 10 Hz. This plot is stable and does not change
> down to 1 Hz RBW:
>
> [image: NANO 1 mHz RBW 10 Hz.png]
>
> Still some strange stuff that looks like aliasing, but the lack of a clean
> fundamental is interesting. Onward we go.
>
> Next is a span of 125 kHz with resolution bandwidth of 3 Hz:
>
> [image: NANO 125 kHz RBO 3 Hz.jpg]
>
> This trace is stable and I imagine it to show the actual output of the
> digital oscillator chip. I just read in QST this morning (Local Oscillators
> for Transverters, by Paul Wade W1GHZ) that "In fractional-N mode, when the
> frequency cannot be divided by an integer, the chip switches rapidly
> between two integer ratios and averages them to the desired frequency". Is
> this what I am seeing? I am not an engineer, just an enthusiastic amateur
> (pun intended).
>
> JJ W0FAA
>
>
> PRIVILEGED AND CONFIDENTIAL DOCUMENT in accordance with Tenn. Code Ann. §§
> 68-11-272 and 63-1-150.
> This E-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended only
> for the use of the Individual(s) named. If you are not the intended
> recipient of this E-mail, you are hereby notified that any dissemination or
> copying of this E-mail is strictly prohibited. Unencrypted email may be
> stored in plain text on many servers. Sensitive information should not be
> sent in this manner.
>
> Sent with Proton Mail <https://pr.tn/ref/NV8FZHYH5PG0> secure email.
>
>
>
>
>

Hi Dave,



Here’s a plot I took today on a Siglent 3021XSA. With 1Hz RBW I don’t seem to
be seeing what you did! The signal is a NanoVNA parked at 100MHz in CW mode.
Will try at 440 next time.![image0.jpeg](cid:87488A01-2C51-45DC-
ADE0-73DC506E7342-L0-001)

Best regards,

Rob Rowlands

415 849 5667



> On Mar 24, 2024, at 10:59 PM, W0LEV <davearea51a@gmail.com> wrote:
>
>

> 

>

> If your SA is an FFT unit and not a scanning SA (the original and older
designs), these may be due to aliasing. At HP, Tektronix loaned us one of
their earlier FFT SAs. It was pretty good on unmodulated signals - CW- , but
anything with modulation, even mild digital modulation, it aliased badly,
especially at smaller RBWs. They have certainly improved, but I still see
aliasing on some digitally modulated signals.

>

>
>

>

> BTW: mHz = milliHertz MHz = megaHertz

>

>
>

>

> Dave - WØLEV
>

>

>
>

>

> On Sun, Mar 24, 2024 at 4:59 AM W0FAA - JJ via [groups.io](http://groups.io)
<W0FAA=[protonmail.com@groups.io](mailto:protonmail.com@groups.io)> wrote:
>

>

>> Had to re-send, [groups.io](http://groups.io) didn't recognize the address
I used:

>>

>>
>

>>

>>> I have been following the discussion of the output of this device with
interest. Here are some captures from my SA that I would appreciate comments
on.

>>>

>>> All show CW output set to 400 mHz.
>

>>>

>>>
>

>>>

>>> First, the harmonics to 3 gHz, this has been well commented on:

>>>

>>> <NANO Harm.png>

>>>

>>>
>

>>>

>>>
>

>>>

>>> Next, an attempt to view the fundamental from 30,000 feet so to speak,
looks nice!
>

>>>

>>> <Nano 50 mHz RBW 300 Hz.png>

>>>

>>>
>

>>>

>>>
>

>>>

>>> Next, I was interested in a closer examination. Here is 2.5 mHz with RBW
of 10 Hz:

>>>

>>>
>

>>>

>>> <NANO 2.50 mHz RBW 10 Hz.png>

>>>

>>>
>

>>>

>>> This starts to look very messy to me, aliasing or something going on, so
onward we go.

>>>

>>>
>

>>>

>>> Here is 1mHz with RBW of 10 Hz. This plot is stable and does not change
down to 1 Hz RBW:

>>>

>>>
>

>>>

>>> <NANO 1 mHz RBW 10 Hz.png>

>>>

>>>
>

>>>

>>>
>

>>>

>>> Still some strange stuff that looks like aliasing, but the lack of a clean
fundamental is interesting. Onward we go.

>>>

>>>
>

>>>

>>> Next is a span of 125 kHz with resolution bandwidth of 3 Hz:

>>>

>>>
>

>>>

>>> <NANO 125 kHz RBO 3 Hz.jpg>

>>>

>>>
>

>>>

>>>
>

>>>

>>> This trace is stable and I imagine it to show the actual output of the
digital oscillator chip. I just read in QST this morning (Local Oscillators
for Transverters, by Paul Wade W1GHZ) that "In fractional-N mode, when the
frequency cannot be divided by an integer, the chip switches rapidly between
two integer ratios and averages them to the desired frequency". Is this what I
am seeing? I am not an engineer, just an enthusiastic amateur (pun intended).

>>>

>>>
>

>>>

>>> JJ W0FAA
>

>>>

>>>
>

>>>

>>>
>

>>>

>>> PRIVILEGED AND CONFIDENTIAL DOCUMENT in accordance with Tenn. Code Ann. §§
68-11-272 and 63-1-150.
>

>>>

>>> This E-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended only
for the use of the Individual(s) named. If you are not the intended recipient
of this E-mail, you are hereby notified that any dissemination or copying of
this E-mail is strictly prohibited. Unencrypted email may be stored in plain
text on many servers. Sensitive information should not be sent in this
manner.
>

>>>

>>>
>

>>>

>>> Sent with [Proton Mail](https://pr.tn/ref/NV8FZHYH5PG0) secure email.

>>

>>
>

>

>
>
> \--
>

>

> **Dave - WØLEV
> **

>

>
>

>

>
>

_._,_._,_

* * *