|Subject:||Re: [TowerTalk] A3S 20 Meter troubles|
|From:||Bill Coleman <email@example.com>|
|Date:||Tue, 1 Jun 2004 08:02:36 -0400|
On May 31, 2004, at 3:48 PM, firstname.lastname@example.org wrote:
I just put up an A3S on top of my new 40 ft tower. It is a used A3S and it was reported to work well prior to me getting it last fall.
From what I understand, the antenna does not have 20m traps to fail or get clogged...
Double-check the element spacing according to the manual, particularly the driven element.
Plot an SWR curve for the antenna on 20m. If it doesn't look like that printed in the manual, then something is wrong, likely with the 15m (outboard) traps on the driven element. The reflector and director have less effect on the SWR curve.
You may have to rebuild the traps. One suspect is the connection of the trap ends to the antenna elements, which is generally made with a galvanized screw. This connection can loosen over time, or it may corrode, particularly if moisure is allowed to collect in the trap. If either if these connections were bad, it might work OK on 10m/15m, but not at all on 20m.
A lot of times, insects can get into the drain holes of these traps and fill them with all kinds of debris. On a used antenna, it is a good idea to open up the traps and inspect them. You can do a pretty good job by pulling the plastic end caps off and blowing them out with compressed air. I've had my A3S about 15 years, and had to do this when I re-installed it after a move three years ago.
Bill Coleman, AA4LR, PP-ASEL Mail: email@example.com Quote: "Not within a thousand years will man ever fly!" -- Wilbur Wright, 1901
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
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