[TowerTalk] Need Inverted L advice

[Lee Buller]

At 05:50 PM 12/2/98 GMT, you wrote:
>
>
>Scott, have you measured the self-resonant frequency of your tower
>with beams on top? If it's anywhere close to 1.8, it will drastically
>affect the feedpoint of the L as you show it. 
>
>Without knowing the tower's self-resonant frequency, it's going to be
>very hard to anticipate the feedpoint Z of the L. You may want to
>consider just loading the tower with one of the wire gamma match
>arrangements to be found in the various antenna books. Given the
>tower's thickness, and all the beams on top, you may not need the L
>for anything.
>
>I would estimate you couldn't put an L anywhere on your property
>without the tower modifying the L impedance and/or pattern.
>
>73, Guy


Guys has a good idea Scott.  Goe up your tower about 3/4 of the way and
hank out metal arm....3 to 5 feet out from the tower.  Attach #12 wire
(Make a good electrical connection) and drop it down the tower.  Drive a
stake into the dirt about 3 to 5 feet out...and use a capacitor to feet it.
 Shield goes to the ground and radials.  You just gamma matched your tower.
 If you can;t get it matched, then use an Oemga match, but it will be
sharper in resonance.  Instead of #12 or #10 wire, use a hunk of old coax
as the gamma match wire and use the braid as the wire.  Gives you a little
more bandwidth on 160 by using a thicker wire.  At least that has been my
experience.  I've done this with a 50 foot tower and a TH6 and works FB.
Used a 365 pf broadcvast variable for 100 watts and had a ball.  Remember
the beam on the top acts a a capacitor hat.

Lee
k0wa@southwind.net



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