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[TowerTalk] TVI Filters

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Subject: [TowerTalk] TVI Filters
From: (
Date: Sat, 27 Sep 1997 23:39:48 -0400 (EDT)
In response to Richard, N7TR I suggest the following when trying to get rid
of a
TVI problem with neighbors.

First, inform your neighbor you are concerned about the problem but often it
is not
your fault but perhaps their TV or VCR (VCR's are the biggest problem as the
ones have little protection).   But that you will take a look at the problem.

Second, I find that at least 50% of the TVI is not on the air but the
interference is
coming in on the AC lines.   Hence, I suggest first trying a AC Line Filter
on both
their TV and VCR.   I would bet that will make a big difference right away.

Third, go for the TVI filter if the AC Line filter doesnt do the job.   I
like the Unadella
filters the Cable industry uses.   They are expensive but solid filters
leaving little
chance for not getting any RF out of the feed to TV's and VCR'[s.   Put it
right at the
antenna input to the TV and VCR.   Use no open wire twin lead between the TV
and VCR but only shielded cable.    

My bet is that in most instances that the above will do the job.   In the
case of my neighbor I was able to get just about all of the TVI out but there
was still a problem.
I examined the feeds to the TV and spotted three inches of 300 ohm flat open
It was on a splitter for UHF/VHF.   I replaced it with a coax fed splitter
from Radio 
Shack and that wrapped up my problem.

I often find that the Radio Shack 15-579 TVI filter will do the job.   Try
one!            They are just $5.00 and not a big financial risk.   The
Unadella I mentioned are now over $30 a piece. (They are now called the HP-50
FastTrap from Microwave Mafg)   

No, you are not obligated to pay for filters or anything else to solve TVI
problems but
its a good way to keep the neighbor on your side and peace in the

Be sure you have a good low pass filter on your rig.    Its not only a good
idea to
prevent problems but is classified by the FCC as "operating in good

Good luck!


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