What you are measuring is DM loss through the balun. Ideally, this should
be low. The Smith Chart, S21, and S11 all look about right for that
measurement. If you wish to measure CM attenuation, connect just the braid
between the two ports. That is the path the CM energy 'sees'.
Dave - W?LEV
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On Wed, Feb 10, 2021 at 1:21 PM Chris Keladis <ckeladis@...> wrote:
I've been testing a balun with the following specifications:
2x FT240-31 Amidon cores stacked
11 turns of RG-400 teflon-coated coaxial cable
A photo of the baluns internals:
[image: balun.jpg]
This balun feeds a ground-mounted Hustler 5BTV.
I followed David's W0LEV's guide on CMC checking with nanovna-saver.
Calibrated for 1mhz-30mhz with OSL and Thru using the supplied coaxial
jumpers and loads. Here's my test-rig:
[image: 20210208_200439.jpg]
I calibrated OSLT with the connectors at the end of the pigtails.
This is what i see on Nanovna-Saver:
[image: nanovna_saver.png]
My SWR, Smith and S21 Gain values and graph are totally different to
Davids.
This balun works ok, i pulled it out of service to measure.
I see ~1.5:1 with a roughly tuned 5BTV on 40M @ 100w.
David's numbers seem to make sense, my numbers seem a bit confusing, but
it does work.
Any thoughts why the difference between the results?
Would appreciate your thoughts :)
73s & thanks!
Chris.
On Sun, Feb 7, 2021 at 9:00 AM David Eckhardt <davearea51a@...>
wrote:
It was requested by a number of responders that I convert to PDF. The
attachments are in .PDF format which should be able to be read by
everyone.
There was also a request to place them in the files section of these
NANOVNA sites. I am a member and will attempt that. However, if the
moderators don't see them there, please place them there.
Dave - W?LEV
--
*Dave - W?LEV*
*Just Let Darwin Work*
