Your coax is only going to have a "resonant frequency" if it is terminated
in a very high SWR or a load with a very high or low impedance, such as an
open or short. If the load is somewhere close to 50 ohms, you aren't going
to see any resonant frequency that is worth any concern.
Zack W9SZ
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On Fri, Mar 21, 2025 at 6:56?AM Team-SIM SIM-Mode via groups.io <sim31_team=
[email protected]> wrote:
Hi
DiSlord Coax Zc measurement function, already installed on H4 1.2.40
firmware, seems need to measure C0 capacitance @ 100Khz and the f0 first
coax resonance frequency (Hz) and then we calculate Zc = 1/(4 x f0 x c0)
Ohm , I appreciate it a lot.
Can we do some accuracy correction ? indeed diélectric permittivity of
polyethylene diélectric can vary with fréquency , it can decrease slowly up
to -4.5% from 100Khz to 14.1Mhz for example , so we can correct C0 value by
-4.5% and then ZC should be increased by +4.5% to be more accurate @ 14
Mhz Zc measurement .
if our coax has 22.28 metre long with Vp around 83% , the first resonnance
frequency will be around 2.71 Mhz wich still far from 14Mhz and may be
some % error may be done , I prefer to measure the resonnance or
antiresonance the nearest to the 14Mhz and devide by number for correction
to have the more accurate Zc value based on measurement done as near as
possible to the desired frequency ..
What you think about all this view , or DiSlord has already taken in
consideration all this possible corrections .
73's Nizar .
