[AMRadio] Antennas
Jim Wilhite
w5jo at brightok.net
Fri Oct 16 20:33:49 EDT 2009
For almost all the past week it has been foggy, drizzly and dark here so
I spent most of my time in the shack working on things indoors. One
thing I did is hook my antenna analyzer to the feedline of each of my
antennas to see how they might perform this winter season. I do regular
maintenance on my equipment each year by pulling transmitters and
receivers out of the cabinet to look for anything burned, smoked,
cracked or not just right. It was time for the antennas to get a once
over since it has been over 4 years since installation.
Well two of the three showed that things had changed significantly in
the last 2 or 3 years. So today, I changed the feedline to my 80/40
meter dipole and the one that feeds my beam. The match to both had
deteriorated to a degree and, if allowed to remain in their present
state, would be worse before this winter season was over. It turned out
moisture had seeped into some of the feedline where it attached to the
antennas, contaminating the coax.
I changed the coax and method of connection to the antennas today
because the weather was just beautiful. Now the analyzer reads that
match efficiency and phase angle are on the money. We aren't going to
have too many more days that lend themselves to work outside, so I urge
you to pick a nice day like it was here and check all your antennas to
be sure they will hold up this winter. Another thing I did is use a
pliable seal on connections outdoors.
A little preventative work today will keep those AM radios going this
winter. Something I discovered this past week is that if you will look
for a product called "Tacky Tape", it is much like the famous "Coax
Seal" sold by radio people for a big price for a little bit. Tacky Tape
is just like it and you get a lot more for your buck. Do a search for
it, I found it for $2.99 for 5 yards X 1/4 inch wide. Coax Seal was
$3.80 for 1/2 by 5 ft. 1/2 X 12 ft. was over $16. Have fun this winter
and I look forward to talking to many of you on the air.
73
Jim/W5JO
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