[TowerTalk] Shunt Fed Tower - 160 Meter Gamma Match Question

[Larry K4AB]

Chuck,

I've installed a lot of 160 shunt feeds.  I would start by raising the gamma
attachment point.

Usually 2/3 the height of the tower would be fine. In your case 90' should
work well.

GL!

73,
Larry K4AB

On Mon, Feb 15, 2010 at 10:35 AM, Chuck <w5pr at swbell.net> wrote:

> I am trying to shunt feed a tower for 160 meters.  I have a 135' Rohn 55
> tower with several good sized antennas on it.  Guys are insulated.  I have
> run an old piece of coax up 35' about 2' off the tower for a gamma.  I have
> about a 150 pf variable in series and 200 pf to ground.  Ground is 2 -140
> foot radials, elevated 10'  (In the past I think I have used larger
> capacitors for this.)
>
> I do not get any match on the series variable with 200 pf, 100 pf and 0 pf
> to ground.
>
> What is the easiest thing to do now?
>
> 1.  Shorten the radials?
> 2.  Increase the series capacitance?
> 3.  Increase the capacitance to ground?
>
> Is my gamma too short?
>
> Thanks!
>
> Chuck W5PR
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