[BC] FM bays

[Glen Kippel]

On Thu, Feb 12, 2009 at 3:37 AM, r.j.carpenter <rcarpen at comcast.net> wrote:

> Should this discussion be expanded from "FM Bays" to include considerations
> of an HAAT considerably greater than 100 meters when the target city is
> 10-15 miles away?

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If you have no population to speak of between the transmitter site and where
your listeners are, and the terrain is reasonably flat, I would say there is
no reason to expend a lot of power to serve an unpopulated area.  Besides,
the elevation angle of a 100-meter tower as seen from 15 miles away is
miniscule.  What -- one degree?  Two, if that?  I see no reason to expend a
lot of RF a mile or two from the site when there is nobody there to listen.
Even if there is some lobing there, there would be nobody there to be
affected.

One station that I did some work for (KSNN Merced) had a similar situation.
There was nothing but flat farm land between their 500-foot tower and town.
The transmission line had been attached to the tower with Ty-Rap -- no
hangers.  So there were lots of holes in the line, and it was possible to
blow out a nitrogen tank in a couple of days.  They got a dehydrator, which
ran continuously.  They were running 25 kW TPO into 5 bays.  I told them
that the line needed to be replaced, and there was probably water in the
antenna, too.  I said, go 8 or 10 bays, cut the transmitter power back and
save over $2000 a month on the power bill.  Their corporate engineer was
from the Phillipines and said 4 or 5 bays works better.  Well, the
Phillippines is pretty mountanous and that probably works there.  Anyway,
they gave me the ax, got another contract engineer, and shortly thereafter
the whole shebang -- antenna, line, transmitter -- burned up.  They told the
insurance company it was lightning.  But there wasn't a cloud in the sky.
I'm glad I wasn't working there, because I wouldn't lie like that.

>