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

To: doc@kd4e.com
Subject: Re: [RFI] Mast-mount TV Pre-Amp -- Avoiding RFI & Overload?
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Thu, 04 Jun 2009 03:10:48 -0400
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
BTW I've been using cheap old Radio Shack remote amps, but they were 
running $50 plus. I use those as they only last a couple of years with 
all the lightning around here.


Roger (K8RI)

Roger (K8RI) wrote:
> kd4e wrote:
>> Actually, a digital signal is either real good or it is real 
>> gone.
> There is a thin band, or very narrow range where the signal breaks up, 
> pixelizes, pauses, or goes out of sync
> between the audio and video, but it is so narrow it is seldom seen. When 
> the signal reaches that level it is susceptible to all sorts of 
> interference.
>> Here in the fringe area we need help to get the signal strength
>> we need for a consistent signal lock.
> I've found the digital signals to be far more reliable than the analog. 
> I now get stations from Lansing and the Northern Detroit area that look 
> as good as locals where the same stations on analog aren't worth 
> watching. I now receive about twice as many off the air signals as I did 
> with analog and the antennas don't seem to be quite as fussy to 
> pointing.  Unfortunately there are two groups of stations with one from 
> SE to SW with another on about 330 degrees.  So I have two antennas 
> which I switch between.  BTW these are only about 10' from the tribander 
> which gets the legal limit.
>> If I could find a mast-mount pre-amp which includes
>> bandpass and low-pass filters, to keep non-TV signals
>> out, then it should do a good job.
> I use antenna mounted preamps on two large UHF antennas that pick up 
> both VHF and UHF.  The low band VHF is strong enough that the UHF 
> antenna does right well. Of course the distance is only about 35 to 40 
> miles over flat land and my antennas are at 90 plus feet.  HOWEVER they 
> are only about 15 to 20 feet above the 144/440 diamond repeater antenna 
> (Up to 160W but normally 50), about 20' below the 7L C3i 6-meter antenna 
> being fed a KW and about 30' below the 144 and 440 arrays with the 
> capability of 1KW out on the 144 band. We are limited to 50 watts on 
> 440.  So far no problems with my antennas but I did get into channel 12 
> on my neighbor's TV in the garage using rabbit ears.  I gave him a good, 
> but small all band TV antenna and that ended that problem.
> I'd go with a 1/4 wave stub to notch out the 2-meter band if it's a 
> problem or build a filter using a group of stubs as they recommend 
> behind the henry 2002A.    A KW on six doesn't seem to bother anything here.
> 73
> Roger (K8RI)
>>  > WA3GIN wrote:
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