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[TowerTalk] Nasty RF Problem. Advice Please

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Subject: [TowerTalk] Nasty RF Problem. Advice Please
From: "CARY GOOCH" <>
Date: Sun, 10 Sep 2006 10:26:02 -0500
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We have an 80ft tower on which reside two tower mount Airstream 5.8GHz
Radios. One fires through a 6ft parabolic 27 miles clean as a whistle.

The other has an integrated antenna, 2 mile shot and taking so much
interference from a 3KW FM Stereo antenna 40 feet higher up the tower
that I can not even log into it (power over Ethernet, shielded cable
with drain wire.

I have moved the antenna, changed polarity, upped the transmit distance
setting, everything I can think of. The only time I do not get RF and
Ethernet frame drops (sometimes 90 percent) is when I have the FM
transmitter turned off.

We also have Nivini (spelling) gear in the building at 2.4GHz, and
though it is working well enough, their tech says they are getting
significant interference as well.  

Barring the obvious (move a whole lot of gear to another tower, time and
money) is there something else I might do?

Now I don't know what an FM Stereo radiation pattern looks like, but
when I woke up this morning it occurred to me that if I had my
radio/antenna setup DIRECTLY below the FM setup, that I might have found
a null spot in the FM pattern? I think that if I can just clean up the
signal in this one antenna that we can live with the interference on the
rest of the gear.

But I don't know if there IS a null spot, or even if it would matter. 

Since my 27 mile shot with parabolic antennas is so clean, I know that
is an option, but these integrated antenna radios do not have options
for external antennas.  New airstream radios for this company are a
rather significant investment.

What can I do?

Advise please. If I have not been clear on any points then ask me to
elaborate. I am just getting some coffee.

Best regards,

Cary Todd Gooch
RF Engineer
New Roads Telecom
(479) 494-0300 X211


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