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Re: [TowerTalk] antennas and towers near broadcast stations

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Subject: Re: [TowerTalk] antennas and towers near broadcast stations
From: "W7CE" <w7ce@curtiss.net>
Date: Sun, 15 Feb 2009 11:02:00 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I almost didn't read this thread thinking it wouldn't apply to me.

There is a 400' tower in town that is triplexed with 3 stations.  The lowest 
frequency station is on 680 kHz.  I located the tower on GoogleEarth and 
determined that it is 4617 meters from my proposed tower location (give or 
take a few meters).  Ten wavelengths at 680 kHz is 4412 meters.  Looks like 
I'm less than half a wavelength outside the 10 wavelength radius.  If had 
been inside, then my tower height would be limited to 44 meters or 144 feet 
without notifying the station and paying for the necessary studies and 
possible detuning.  My current tower plans call for a 110' tower + mast and 
a 72' tower + mast, so I'd be exempt from the notification requirements.

I'm looking for property to build my retirement home on someday, and this is 
one more thing to keep in mind when choosing a location.  CC&Rs on almost 
every property that I look at is still the number one issue.

73,
Clay  W7CE


>
> N2EA Comments:   This is perfectly reasonable, on its face.
> Commercial interests bear the responsibility of assuring
> that their construction... towers or power lines, for example... do
> not impact the pattern of a directional array AM station.
> The cost of re-certifying a directional array... repeating the proof,
> is something on the order of $20,000,  in today's dollars,
> before you add in the consulting engineer's fees.    Been there, done
> that, as they say.   4 times, in fact.
>
> I had a 4 tower AM station go out of licensed Field Strength
> parameters, and had to operate on waivers, for
> over a year, until we identified a high tension line at 2 miles
> distant as the offending construction.   Lawsuit
> followed.   It was $100k legal fees, out of pocket, until the utility
> in question lost, paid up, and detuned their towers.
> Then, we had to repeat the proof of performance, which entailed
> almost $20k in labor, plus a consulting engineer's
> fee of 14k.
>
> Like the idea that amateurs should be exempt from stupid driving
> while distracted by our radios, we are not exempt
> from causing inadvertent harm to commercial operations by our
> construction.  Much as we might like it to be otherwise.
> Thoughtful consideration is in order, with all we do.   (Like
> climbing safely!)
>
> I think the real concern here is cell towers, not us,  just to be
> practical.   Oh,  and just to crank a few numbers,
> a wavelength at 1 MHz is 936'.   10 wavelengths is 1.8 miles.    At
> 1.5Mhz, that's 1.2 miles.   Odds of us affecting
> them at that distance are quite small.   But why should we be exempt,
> if we cause harm?
>
> If we make a vertical resonant on our operating frequency, it is, de-
> facto, non-resonant at the broadcast freq.
> i.e.  decoupled.    And we shouldn't have to worry.
>
> Unreasonable rule making?   I don't think so.
>
> N2EA
> Jim Jarvis, MBA, President
> The Morse Group, LLC
> www.themorsegroup.net
> Leadership and Supervisory Development * Strategic Planning *
> Corporate Coaching
>
>
>
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