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Re: Topband: Trees and RF

To: <topband@contesting.com>
Subject: Re: Topband: Trees and RF
From: "Mel Crichton" <kj9c@iquest.net>
Date: Tue, 3 Nov 2009 16:23:05 -0500
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Purely anecdotal here... I live in a pretty dense hardwood forest. The only 
clearing is where the house sits, where there's a 15 foot rooftop tower holding 
a 2 element quad.... tops of trees are 30 to 70 feet higher. No antenna is 
above treetops.

The HF antennas are all supported by trees and therefore are lower than the 
treetops.  I try to keep the dipole wires clear of branches but occasionally 
something gets snagged. If the snag is close to the feedpoint I will see an SWR 
change.

My 160 inverted L is an insulated wire shot OVER the top of a 90 foot pignut 
hickory.... this is one variety of hardwood that seems to work... I have a 
dozen elevated radials running thru the woods that are tied to trees, bushes, 
whatever is nearby. Depending on how close the feedpoint and lower section of 
wire are to the tree trunk, the resonant point will move up or down the band a 
bit, so each year I add or subtract a couple feet of wire when I restring the 
antenna for the winter. One year the antenna made it to summer, when there were 
leaves on the trees. I manage to make 160 meter QSOs with leaves as well as 
without, with a small difference in SWR. I am sure my signal is down a bit due 
to leaves, but likely not noticeably.

I typically run 100 watts on all bands, especially contesting, but will QRO to 
700 watts on 160 when needed. No fires yet.  DXCC count is 329, with about 150 
worked on 160.  Much line noise around here so RX antennas are critical, as 
well as a good noise blanker. I agree that the RX antennas are more critical to 
working them than my TX antenna, especially last night when I heard everyone 
else working stations that were below the local RFI level. I am sure the other 
guy would have heard me, but I couldn't hear him.

Mel, KJ9C Indiana on the edge of the Black Hole


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160 meters is a serious band, it should be treated with respect. - TF4M

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