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Re: [RFI] Mast-mount TV Pre-Amp -- Avoiding RFI & Overload?

To: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Subject: Re: [RFI] Mast-mount TV Pre-Amp -- Avoiding RFI & Overload?
From: kd4e <doc@kd4e.com>
Reply-to: doc@kd4e.com
Date: Thu, 04 Jun 2009 23:00:58 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
> When you say "out int he woods", are the stations close (strong 
> signals), far, (weak signals) or a mix?
> Are they all (more or less) in one direction?
> What distance ranges and headings (or bearings) are we looking at?

We are north of Tampa and all of the signals come generally 
from
that direction.

Arm-strong rotation of the beam requires only a tiny 
movement to
bring one group of stations in strong and lose several 
others or to
have the majority of them and a few lost but several at the 
compromise
position are erratic.

> Some have filters, some have a filter for the FM and 2 meter band and 
> some don't.  HOWEVER unless you have some really strong TV stations, or 
> the 50, 144, and 440 antennas are going to be very close and of the same 
> polarization I wouldn't be overly concerned to the point of losing 
> sleep. 

I operate 6, 2, and 440.  The closest of those antennas is 
about 30 feet off the
back-side corner of the TV beam.

I currently run less than 100W on 6M and less than that on 2 
& 440.

The 6M antennas are a Delta loop and a horizontally 
polarized beam -
the beam is not yet up but will probably be fixed 
west-northwest - so
back-to-back to the TV beam (and 30 feet away).

I also sometimes use a dipole via a tuner that is further 
away and my 6BTV
HF vertical which is ground mounted about 20 feet away from 
the push-up
pole that supports the TV beam.

> I would get a bit better remote preamp though

Someone recommended a Winegard and I am looking at those - 
bonus
that is it USA-made!

>> Since using a mast-mount pre-amp will eliminate the need for a rotator
>>   
> What makes you think it will eliminate the need for a rotator?  I'm not 
> saying it wont, but if the stations are at a reasonable distance then 
> you may not even need a preamp.  If the stations are mostly in one 
> direction and the antenna is a relatively simple one like a corner 
> reflector of dual bow tie with a screen reflector then it's likely you 
> can get away without a rotator.

The TV beam is a multi-element on VHF and on UHF, it is 
intended
for fringe use.  I don't know the brand as I received it used.

We have a lot of UHF TV stations here in the Tampa area.

> I would go with a better amp, but I think many get overly concerned 
> about possible problems.If it's a simple system, put it up, try it and 
> modify it if necessary.
> 73 Roger (K8RI)

That was helpful info, thanks!

-- 

Thanks! & 73, doc, KD4E
FS/Swap/Wanted: http://kd4e.com/swapn.html
Free OS : http://www.PuppyLinux.com
Personal: http://kd4e.com
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