Whoa.
A gamma match has TWO things to 'change' ... one is the point of
attachment from gamma rod to the driven element ... the other is the
SERIES CAPACITOR in the gamma line.
All gamma matches that I use are tuned by placing the antenna analyzer
about ONE FOOT from the feedpoint, then going back and forth between
the capacitor and the shorting bar .. until the match is what I want
it to be.
The inductive portion of your measurement seems to be due to NOT
having a series capacitor in the gamma match.
73
Don
N8DE
Quoting Chuck <w5pr@swbell.net>:
> I hate adjusting gamma matches through trial and error. I am hoping
> my new antenna analyzer will help.
>
> I computer designed a 10 meter Yagi which designed at a feed
> impedance of 31.2 + j18.3. This is inductive, I assume.
>
> I have a gamma match, the antenna mounted at 15 feet and my antenna
> analyzer says (through an analyzer measured 1 wavelength 50 ohm feed
> line) Z=66 ohms, X=-52 ohms and C=105
>
> My take is to move the tap closer to the boom until it is about Z=50
> ohms and, if there is still a negative X, to lengthen the DE. Of
> course, the changes will interact with each other and I will need to
> go back and forth until Z=50 and X=0.
>
> Am I on the right track?
>
> Chuck W5PR
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