On 10/10/2017 7:59 AM, Dave Hachadorian wrote:
Speaking of "tuning" a choke, couldn't you just run 50 watts into a
dummy load, and tee off a choke and a 100 ohm resistor to ground, and
calculate the impedance of the choke by measuring the RF voltage
across the resistor and the RF voltage across the dummy load?
No, because that's not the common mode circuit. There IS, however, a
method somewhat similar to that which I used for the data I gathered.
It's detailed in this set of slides.
http://k9yc.com/CoaxChokesPPT.pdf
FWIW, I have never gotten good data using any form of reflection-based
measurement system. The problem is that the Z of the choke is much, much
greater than the Z of the measurement system. The error shows up in the
resonant frequency.
73, Jim K9YC
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