gamma's

[Upson,Darrell]

A gamma match that works great and that I used on a homemade 3 el yagi 
 is to extend the center conductor and insulation right into the outer 
 sleeve almost the full length.  Adjust the slider strap between the 
 gamma rod and the driven element for minimum SWR and assuming the 
 resonant frequency is below the frequency you want, trim the end of 
 the center conductor for the desired resonant frequency.  Trim off no 
 more than a half an inch and measure the shift in frequency to 
 determine how much more to trim.  The coax shield of course connects 
 directly to the center of the driven element.  No additional capacitor 
 is used and lasts forever.

Darrell WB6ADZ
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From: owner-towertalk@akorn.net
To: towertalk@contesting.com
Cc: kcubilo
Subject: gamma's
Date: Wednesday, January 15, 1997 2:19PM

hi all i have been designing a 2 el 20 meter yagi and wonder if anyone can
give me some pointers on a gamma match. layout shows a radiation resistance of
approx 35.8 ohms. i want to use 1/2 alum conduit for the outer sleeve of the
gamma but now i am really pulling my hair out trying to figure out what to use
for the inner rod and what type of material to construct the capacitor material
out of. can anyone enlighten me?
thanks and enjoy the group
73 we8w


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