I have done the mod mentioned on several DB-224 antennas by taking some six
inch lengths of an old TV antenna and flattening about three inches on one end
and wrapping the flattened end around the end of the dipole and putting a
machine screw through the flats to hold the extension to the dipole. I then
cut the extension back to two inches.
This has resulted in a lower SWR in the ham band after moving the 155 mHz
antennas down. I have made no changes to the harness to move the antenna.
Something like a change from 1.8:1 down to 1.2:1 is what I have measured at the
antenna.
73 - Jim W5ZIT
--- On Sun, 3/22/09, Tom, N6MVT <n6...@comcast.net> wrote:
From: Tom, N6MVT <n6...@comcast.net>
Subject: [Repeater-Builder] Re: Decibel dipole array sweeps
To: Repeater-Builder@yahoogroups.com
Date: Sunday, March 22, 2009, 4:09 PM
Also, I have seen some of the dipoles get modified with short stainless machine
screws+nuts drilled through the top & bottom of the dipole elements, to help
get the Return Loss even better at lower freqs.
Not sure what, if any, skewed pattern is introduced by doing the machine screw
mod or not. Quite often it's hard to tell any changes in the field unless it is
very drastic.
Tom
