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
----------
From: owner-towertalk@akorn.net
To: towertalk@contesting.com
Cc: kcubilo
Subject: gamma's
To: <towertalk@contesting.com>
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
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: K7LXC@contesting.com
Sponsored by Akorn Access, Inc & N4VJ / K4AAA
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: K7LXC@contesting.com
Sponsored by Akorn Access, Inc & N4VJ / K4AAA
|