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S11 distortion

Open LeCont opened this issue 6 years ago • 3 comments

Hello, Tried different versions: 1.01, 1.0. 0.53, etc. S11 graph looks always distorted: http://lecont.net/wp-content/uploads/2019/06/0000018.jpg Minor distortions (steps) are also visible on other graphs.

From the other hand, original EU1KY firmware does not have this issue (same hardware used): http://lecont.net/wp-content/uploads/2019/06/00000017.jpg

Do appreciate your feedback. Evgeny

LeCont avatar Jun 12 '19 14:06 LeCont

I tried to confirm your problem, with CEC V1.01. I cannot confirm this error, my screen is as expected. Please let me know your concrete testing conditions. 73, Wolfgang, DH1AKF

ted051 avatar Jun 12 '19 15:06 ted051

Hi Wolfgang, thanks for your prompt response. After I have reduced a number of turns on choke (now there are 4, before - 6) and relocated it on the side of the board, the issue apparently resolved. http://lecont.net/wp-content/uploads/2019/06/IMG_6697.jpg Strange thing is that I have experienced the same issue on 3 different devices and only on CEC firmware, not on EU1KY one. Could you please advice what is the right type of ferrite for the choke and what is the most optimal number of cable turns on it? Thanks, Evgeny

LeCont avatar Jun 12 '19 20:06 LeCont

Even Juri Kuchura (EU1KY) did not provide more precise information on the core. I used cores from an old VGA cable, µ about 800nH/w². 4 turns 50 Ohm Teflon coax.

ted051 avatar Jun 13 '19 09:06 ted051