[TowerTalk] Adjusting a Gamma Match on a Yagi with an Antenna Analyzer

[n8de at thepoint.net]

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 at 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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