Will the reactance of NanoVNA's channels influence the resonant
frequencies of the choke, or the calibration process is removing this
influence?
If the influence is present, what method will minimize it the most?
Should the choke be measured mounted in the PA, to include the influence of
the neighboring objects?
73 Ady YO2NAA
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On Sun, Dec 22, 2019 at 2:34 PM Jim Potter <jpotter@...> wrote:
To find a series resonance you are looking for the frequency where the
impedance is a minimum.
All three techniques you suggest will work.
1. Series between two ports, look for the frequency of maximum S21
2. Shunt, you only need 1 port. Look for the frequency of a dip in S11.
Don't connect Port 2
3. With two coupling coils the result will be like #1, The frequency for
maximum S21 is the self resonance
4. With one coupling loop the series resonance will be the minimum in S11,
like #2. This is pretty much what you are doing with the grid dip meter,
looking for maximum energy absorption,
Try all of these techniques to see the difference. That's one of the great
thing about the nanoVNA it's a great educational tool at an affordable
price.
73 de K9GXC, Jim
