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[TowerTalk] Commercial FM Station Interference

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Subject: [TowerTalk] Commercial FM Station Interference
From: (Larry A. Crim)
Date: Mon, 9 Jun 1997 23:15:35 -0500 (CDT)
On Mon, 9 Jun 1997, Ken Anderson wrote:

> Is there a station engineer or otherwise knowledgeable person
> on FCC standards for location of Commercial FM stations.

As a soon to be former owner/operator of over 7 commercial FM stations I 
am somewhat knowledgeable, depending on with whom you ask.

> The station in question is a Class A at 107.5 MHz (second harmonic is
> in Ch13 the local CBS affiliate!) running 6KW to an Omni antenna at 
> 60 feet above local terrain.  Is this a normal situation for such stations?

I have operated FM stations from 410 watts to 100kw, from 92.5 mHz to 
106.9 mHz and have never had a single TVI complaint in over 19 years in 
the business.  If there IS a real TVI problem, it is probably the fault 
of the FM broadcaster.

> I've searched the FCC web sites and can't find any guidelines on 
> locating such antennas/stations within residential areas.

As far as I know, there aren't any.  But speaking from practical 
experience, a properly engineered and installed Class A FM station could 
operate in a residential environment without any TVI problems.

Call the Chief Engineer at the station in question and ask him if the 
"harmonic filter" has been installed properly or has it been omitted
for "economic reasons".

-Larry K4AB

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