Have you been on the tower when the problem occurs? Sounds like it might
be a vibration problem due to the wind through the guys.
If this is the case, you could try installing vibration dampners on the
guys. These are plastic spirals several feet long that wrap around the
guy. They are available from Preformed Line Products.
Of course, you want to make sure there is absolutely nothing loose on the
tower, especially near the antenna. This could be tower hardware, loose or
corroded ground connections, etc. Anywhere there might be loose metal to
metal contact, especially between dissimilar metals should be suspect.
Your hardline shield should be grounded to the tower at the antenna
connector and at the ground.
Folded dipole antennas are usually pretty good for intermod problems, but
it's always possible something is loose in the antenna array. You could
try swaping out the antenna temporarily with simple 1/4 wave vertical.
GL! Ty K3MM
w4an@contesting.com on 08/26/97 11:15:24 AM
To: towertalk@contesting.com
cc: aseabolt@gadoe.gac.peachnet.edu (bcc: Tyler G Stewart/BENN/CEC)
Subject: [TowerTalk] Noise caused by tower.
Our local 2-mtr repeater is having some problems. We are experiencing
noise caused by what is believed to be something on the tower when the
wind blows. When the wind is "howling", the noise is QRV. Anything
short of "howling", and the noise is gone. Below is a desciption of the
installation...
-----------------
We have an 170 ft tower approximately the size of rohn 65 (no rust).
The tower is in 20 foot sections and bolted together with 3 bolts per
section. The guying is 40 foot apart with 1/4 inch cable on the first set
of guys and 3/8 inch cable on the top three guys. The guys are attached to
the tower with guy grips. The tower has only one antenna, a celwave PD 654
(8 folded dipoles) for a 146.835 + 600 repeater.
If you shake the guys, the noise will take out a weak signal and it can
be heard on a medium signal. A strong wind has the same results. If you
turn the transmitter off, the noise is no longer heard in the receiver. We
strapped the guy grips to the tower and helped the noise problem by 50 to
70 percent but its still a problem at times. The thing I can't
understand
------------------
Any of you experts have any ideas?
73
Bill, W4AN
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