[TowerTalk] Help needed, antenna SWR

[Jon Suehiro]

Gary, I had a similar condition to my 160 inv. L.

Assuming no antenna performance improvement, but I added 1:2 Balun (25 to 50
ohms - UnUn) at the feeding point.   Antenna V.S.W.R. seen from the shack is
improved to near 1:1.2 without any other effort.

P.S. You may have to consider switching configuration since UnUn isolates
D.C., and you want to place the antenna end of the antenna switch.

GL & 73 de NN5T Jon Suehiro


To: towertalk at contesting.com
Subject: [TowerTalk] Help needed, antenna SWR
From: "Gary Smith" <Gary at ka1j.com>
Reply-to: Gary at ka1j.com
Date: Mon, 20 Jun 2016 22:58:19 -0400
List-post: <towertalk at contesting.com">mailto:towertalk at contesting.com>

I did some spring maintenance on my antennas and need advice on how 
to get a 1.1 match.

I have a radial plate with somewhere around 50 130' radials. I have 5 
wire antennas attached to this and use an Ameritron remote coax 
switch to select which antenna to use. There is a sloper for 160, 
INV-L for 80 and verticals for 40, 30 and 20. 17 & 24M are obtained 
by selecting either the 160 or 80M antennas. No tuner.

I took the Antenna analyzer down to the antennas today and found 80M 
is SWR 1.8, 40 is SWR 1.9, 30M is SWR 2.35 to give some values. The 
lowest SWR I could get on 30M is 2.35 and the antenna is cut for the 
right length for minimum SWR at 10.100 MHz. This gives me the lowest 
SWR on the bands.

I would like to get the SWR down as low as 1.1 at my desired 
frequencies If I can do so, but I'm not sure of the best way to do 
this. I suspect inductance from a coil at the individual feed points 
would work after I get the to SWR dip the lowest at the desired 
frequency but if this is the solution, what would be a good way to 
know do make such coils for each of the antennas? 

The antennas are 350 feet away, in the woods & onto a salt marsh and 
for me, right now, walking is very difficult to do and I want to make 
as few trips as possible.

Suggestions appreciated.

73,

Gary
KA1J
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