Topband: Feeding a vertical

[Lloyd Berg N9LB]

Hi Jake!

I tried this and it worked - sort of...

I have a 60 foot tower gamma-matched for 60, 80 and 160 meters with a 
stack of VHF/UHF antennas on the top.  Coax lines for the VHF antennas 
are tied to one leg of the tower on the inside.

I originally used copper water pipe for the gamma match in the center of 
the tower.  I could get a good match the VHF coax cables were mega-hot 
with RF going into the house.  Those cables are in PVC conduit under 
ground, under the radials.

Moving the copper water pipe gamma match to the outside of the tower 
resulted in more than doubling the radiated field voltage and the VHF 
coax cables are now free of the 60-80-160 RF.

Relative radiation efficiency voltage was measured at the end of my 
driveway, about 240 feet away - you can see the layout on Google Maps, 
Satellite View.  You can see the gamma matched tower on my QRZ page.

73

Lloyd - N9LB


On Wed, Oct 31, 2012 at 12:19 PM, jcjacobsen at q.com wrote:

> How do to all,
> I have a hypoth--er hipoth--oh, alright, a theory, question for all. 
> Take a grounded, 1/4 wave vertical (pick your band/freq of interest) 
> made of tower sections. You're going to feed it with a gamma match. 
> Could the gamma match rod go on the inside of the tower sections for 
> protection?? And, yes, I know, you could insulate the tower from 
> ground and series feed it. BUT, after all this is a hypoth....er 
> hipoth....theory question.
> 73 es GDDX.
> K9WN Jake _______________________________________________
> Topband reflector - topband at contesting.com