Sort out the routing of the feeder & as W8AEF has noted, make
sure the TV stuff is all done right.
Grounding may make things worse. I feed my telly with off-air
VHF & UHF signals far under 60~80 dBuV & without grounding,
without filtering or anything other than the basic stuff & a
little commonsense in the shack - TVI is never a problem. I find
that an RF ground is pretty much a non-starter - a safety ground
yes, but no RF ground that wasn't something other than ground
at some frequency. Even if I were on the ground floor, the ground
will be counter-productive.
Balanced lines stay balanced the whole way. They _must_ be
some ways away from anything else conductive.
My unshielded, ungrounded tuner sits <1m from my telly, with
the feeder equally close & the feedpoint of the inverted-vee
doubtlet it connects to no more than about 5m above it. I have
more problems from the arcing in the roller inductor than anything
else.
There is a need for more information yet in order to provide a
thorough answer - like physical relationship between antenna &
feeder to CATV drop & wiring in the house. The black magic
aspect to RF means that even my suggestions are not necessarily
applicable.
But it is fair to say the problem should not be happening. From W7,
I used to hang a folded 80m dipole from 14m mast next to typical
wooden suburban house, again not far from off-air VHF-only telly
aerial, no grounding anywhere, balanced feeder to tuner & never
any TVI. No LP filter, no HP filter - _no_ nothing.
There is a reason & after finding it, it will make sense. In time, it
will not seem so much like black magic.
73, VR2BrettGraham
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Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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