I saw a note on the Towertalk list about measuring a certain balun. My
question relates to the coiled 'choke' baluns at VHF. There are lots of
rules-of-thumb about how many turns, etc, but even the Balun/Unun book is
sketchy on specifics. I'd like to do some testing to see what the impedance
on the outside of the shield is at various frequencies for various diameters
and turns. Using something like the MFJ antenna analyzer, is it as simple as
connecting the shield at one end and and the shield at the other end to the
coax connector on the MFJ respectively? I would assume high R and/or jX is
goodness? Is one better than the other?
Does anyone have any good starting points they've found? All of the ones
I've made don't seem to make a difference in the QSOs, the SWR (I know, not
supposed to either), the RFI, etc. In fact, sometimes it's better without!
I would like to do some more testing though to understand it better. Is the
MFJ method above valid? Any points at which it would not be?
73, Skip
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