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MORE CMC SINGLE CORE DATA


David Eckhardt 2021/01/17 00:03

Subject: single 31 material 2.4" OD core
12 bifilar turns of insulated AWG #12 stranded
wire

1.90 MHz 3.0 kΩ
3.75 MHz 4.3 k
7.15 MHz 4.5 k
10.125 MHz 4.4 k
14.20 MHz 4.1 k
18.1 MHz 3.8 k
21.30 MHz 3.5 k
28.40 MHz 3.0 k

Except for 160, there is general agreement with a bit less Z than K9YC with
my single 2.4" 31 material core. You can compare the numbers as they're
not too far apart. I don't know how he got more than 12 bifilar turns on
the 2.4" OD core! I squeezed and could not get more than 12 bifilar
turns. I might get a tight 13th if input and output were immediately next
to eachother. He must be overlapping turns to get upwards of 18 bifilar
turns on the single 2.4" core.

What I do observe over my multi-core CMCs is that the linear magnitude is
far more constant over the HF frequencies with the single core and no
suggestion of resonances, just a nice smooth curve. Of course, Z-Mag takes
a nose dive below 1 MHz.

Dave - W ØLEV

Siegfried Jackstien 2021/01/17 00:26

what about stacking two cores?? similar material used ... maybe a few
less turns (guessing 8 to 10 are ok)

otherwise 10m may run away a bit

3 k on 160 ... and 3k on 10 ... other bands more in the 4 k range ...
not bad :-)

i would try two stacked 2.4 inch cores (or even three)

and about winding ... did you turn your bifilar windings?? or are they
flat (no turning of the two cónductor wire)???

greetz sigi dg9bfc

Am 17.01.2021 um 00:03 schrieb David Eckhardt:

Siegfried Jackstien 2021/01/17 00:27

you told us the "impedance" ...

what about "loss" (attenuation of common mode) in db?? that is what you
measure (s21) with the vna ... not??

dg9bfc sigi

Am 17.01.2021 um 00:03 schrieb David Eckhardt:

David Eckhardt 2021/01/17 00:39

My first 31 material CMC was with five stacked cores for power handling
capability. That data has been previously posted. Yes, my next try will
be with two stacked 31 cores. The five-core CMC did quite well on 160 but
was a compromise on the higher HF bands.

I do not twist or cross windings in my builds. I've tried twisting. It
adds more capacitance to the windings which slightly lowers the effective
Zo of the transmission line on the core. If true 50-ohm Zo transmission
line impedance on the core(s) is required, I've found (as did Sevick) that
one needs to go to slabline windings (flat conducting tape). Obtaining a
Zo of 50-ohms on the core is a task and difficult to embody on the core. I
once wound an 80-ohm CMC, but every turn was tied together with multiple
nylon ties. I'm not going there again in my experiments!

Dave - WØLEV

On Sun, Jan 17, 2021 at 12:26 AM Siegfried Jackstien <
siegfried.jackstien@freenet.de> wrote:

> what about stacking two cores?? similar material used ... maybe a few less
> turns (guessing 8 to 10 are ok)
>
> otherwise 10m may run away a bit
>
> 3 k on 160 ... and 3k on 10 ... other bands more in the 4 k range ... not
> bad :-)
>
> i would try two stacked 2.4 inch cores (or even three)
>
> and about winding ... did you turn your bifilar windings?? or are they
> flat (no turning of the two cónductor wire)???
>
> greetz sigi dg9bfc
> Am 17.01.2021 um 00:03 schrieb David Eckhardt:
>
> Subject: single 31 material 2.4" OD core
> 12 bifilar turns of insulated AWG #12 stranded
> wire
>
> 1.90 MHz 3.0 kΩ
> 3.75 MHz 4.3 k
> 7.15 MHz 4.5 k
> 10.125 MHz 4.4 k
> 14.20 MHz 4.1 k
> 18.1 MHz 3.8 k
> 21.30 MHz 3.5 k
> 28.40 MHz 3.0 k
>
> Except for 160, there is general agreement with a bit less Z than K9YC
> with my single 2.4" 31 material core. You can compare the numbers as
> they're not too far apart. I don't know how he got more than 12 bifilar
> turns on the 2.4" OD core! I squeezed and could not get more than 12
> bifilar turns. I might get a tight 13th if input and output were
> immediately next to eachother. He must be overlapping turns to get upwards
> of 18 bifilar turns on the single 2.4" core.
>
> What I do observe over my multi-core CMCs is that the linear magnitude is
> far more constant over the HF frequencies with the single core and no
> suggestion of resonances, just a nice smooth curve. Of course, Z-Mag takes
> a nose dive below 1 MHz.
>
> Dave - W ØLEV
>
>
>
>

--
*Dave - WØLEV*
*Just Let Darwin Work*

David Eckhardt 2021/01/17 00:43

What I have (so far) measured and presented addresses the impedance
presented to common mode energy. I can also measure loss, but my
requirement of minimal heating, and I do mean minimal, indicates low loss.
I can include measurement of DM loss current in future presentations.

Dave - WØLEV

On Sun, Jan 17, 2021 at 12:27 AM Siegfried Jackstien <
siegfried.jackstien@freenet.de> wrote:

> you told us the "impedance" ...
>
> what about "loss" (attenuation of common mode) in db?? that is what you
> measure (s21) with the vna ... not??
>
> dg9bfc sigi
> Am 17.01.2021 um 00:03 schrieb David Eckhardt:
>
> Subject: single 31 material 2.4" OD core
> 12 bifilar turns of insulated AWG #12 stranded
> wire
>
> 1.90 MHz 3.0 kΩ
> 3.75 MHz 4.3 k
> 7.15 MHz 4.5 k
> 10.125 MHz 4.4 k
> 14.20 MHz 4.1 k
> 18.1 MHz 3.8 k
> 21.30 MHz 3.5 k
> 28.40 MHz 3.0 k
>
> Except for 160, there is general agreement with a bit less Z than K9YC
> with my single 2.4" 31 material core. You can compare the numbers as
> they're not too far apart. I don't know how he got more than 12 bifilar
> turns on the 2.4" OD core! I squeezed and could not get more than 12
> bifilar turns. I might get a tight 13th if input and output were
> immediately next to eachother. He must be overlapping turns to get upwards
> of 18 bifilar turns on the single 2.4" core.
>
> What I do observe over my multi-core CMCs is that the linear magnitude is
> far more constant over the HF frequencies with the single core and no
> suggestion of resonances, just a nice smooth curve. Of course, Z-Mag takes
> a nose dive below 1 MHz.
>
> Dave - W ØLEV
>
>
>
>

--
*Dave - WØLEV*
*Just Let Darwin Work*

David Eckhardt 2021/01/17 03:25

Here is measured data in a 50-ohm system of DM mode loss as a function of
frequency

Subject: single 31 material 2.4" OD core
12 bifilar turns of insulated AWG #12 stranded
wire

1.90 MHz CM lin. mag 3.0 kΩ DM Loss: -0.03 dB
3.75 MHz 4.3 k -0.07
dB
7.15 MHz 4.5 k -0.15
dB
10.125 MHz 4.4 k -0.57 dB
14.20 MHz 4.1 k -1.0 dB
18.1 MHz 3.8 k -1.4 dB
21.30 MHz 3.5 k -1.8 dB
28.40 MHz 3.0 k -2.5 dB
50.00 MHz -2.5
dB

I base my 'heating' of the CMC at full legal limit (1.5 kW), key down for
3-minutes on 40-meters. That has led to the multiple core approach. I
also have a home brew little piece of test equipment that shows me the
current on each conductor of the open wire feeders. This indicates balance
from the CMCs up the feedline to the antenna (how well the CMCs are
working). No set of wires is completely balanced due to terrain and height
variations along the deployment of each half of the doublet.

As I previously commented, my application is with a 450-foot long doublet
fed with open wire. So, the load impedance (in transmit) is anything but
50-ohms. The CMC is on the output of the home brew L-network matching
network (a.k.a., antenna 'tuner'). The input of this network is the
transceivers which require 50±j0 ohms. I am most concerned with 160
through 40-meters.

Next, I need to invoke the NANOs to measure the impedance as a function of
frequency presented by the antenna/feedline combination in the shack. I
must use the NANOs for this purpose as I need to connect directly to the
ends of the open wire feed with no additional 'closures' to the RF
circuit. The 8753C would not provide that luxury as it requires CM
connections and I do not want to measure through the CMCs.

Dave - WØLEV

On Sun, Jan 17, 2021 at 12:43 AM David Eckhardt via groups.io <davearea51a=
gmail.com@groups.io> wrote:

> What I have (so far) measured and presented addresses the impedance
> presented to common mode energy. I can also measure loss, but my
> requirement of minimal heating, and I do mean minimal, indicates low loss.
> I can include measurement of DM loss current in future presentations.
>
> Dave - WØLEV
>
> On Sun, Jan 17, 2021 at 12:27 AM Siegfried Jackstien <
> siegfried.jackstien@freenet.de> wrote:
>
>> you told us the "impedance" ...
>>
>> what about "loss" (attenuation of common mode) in db?? that is what you
>> measure (s21) with the vna ... not??
>>
>> dg9bfc sigi
>> Am 17.01.2021 um 00:03 schrieb David Eckhardt:
>>
>> Subject: single 31 material 2.4" OD core
>> 12 bifilar turns of insulated AWG #12 stranded
>> wire
>>
>> 1.90 MHz 3.0 kΩ
>> 3.75 MHz 4.3 k
>> 7.15 MHz 4.5 k
>> 10.125 MHz 4.4 k
>> 14.20 MHz 4.1 k
>> 18.1 MHz 3.8 k
>> 21.30 MHz 3.5 k
>> 28.40 MHz 3.0 k
>>
>> Except for 160, there is general agreement with a bit less Z than K9YC
>> with my single 2.4" 31 material core. You can compare the numbers as
>> they're not too far apart. I don't know how he got more than 12 bifilar
>> turns on the 2.4" OD core! I squeezed and could not get more than 12
>> bifilar turns. I might get a tight 13th if input and output were
>> immediately next to eachother. He must be overlapping turns to get upwards
>> of 18 bifilar turns on the single 2.4" core.
>>
>> What I do observe over my multi-core CMCs is that the linear magnitude is
>> far more constant over the HF frequencies with the single core and no
>> suggestion of resonances, just a nice smooth curve. Of course, Z-Mag takes
>> a nose dive below 1 MHz.
>>
>> Dave - W ØLEV
>>
>>
>
> --
> *Dave - WØLEV*
> *Just Let Darwin Work*
>
>
>
>

--
*Dave - WØLEV*
*Just Let Darwin Work*

Dragan Milivojevic 2021/01/17 04:26

Making a 100Ω TL is not difficult with PTFE wire
of appropriate dimensions or bare wire and PTFE tubing.
Parallel them to get 50Ω.

On Sun, 17 Jan 2021 at 01:39, David Eckhardt <davearea51a@gmail.com> wrote:

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