At 11:15 AM 8/26/97 -0400, you wrote:
>
>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
Bill...
We have experienced the same trouble here on our .61 machine in Newton, KS.
We get some pretty good winds here...up to 40 miles per hour for extended
periods of time. Our antenna is on top of a 300 foot flour mill. We
tracked it down to the antenna itself. Same symptoms you describe.
We had a very old DB Products antenna with 6 folded dipoles. The phassing
harness was the problem. The antenna takes such a beating up there and it
was really rather in poor matintenance that it caused the noise.
Connections were corroded. We could not tell how bad it was because all the
phasing harness was inside the antenna pole. Since then, DB Product
antennas put their harnesses out side the pole.
We took the antenna down (about 20 feet of aluminum pipe) and stripped off
all the old antennas and harnesses. We then install the Cushcraft four pole
phased array and added another 8 foot to the pole to make it work. We
needed more length. Installed the new antenna and the problem was gone! IT
has been gone for two years now...otherwise it has been with up for over two
years before. There is no noise at all when the wind blows. We are now
using the repeater for ARES and RACES where it could not be dependable before.
Just a thought for you.
Lee Buller
k0wa@southwind.net
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