Much of the ham fear of TVI from their feedlines comes about from the
decades past practice of early TV's having IF's in the 15 m ham band or near
it.
With most of the TV programming today carried by cable or fiber to the home,
there is little likely hood of TVI from ham HF equipment. Even the FM VHF
equipment is usually not a problem. Far more likely is a leaky coax TV
cable causing RFI from shared use of the 2m ham band. Inside the home,
there may be RFI issues from HF, in the way TV recorders are hooked up, and
with high powered HF ham gear close to the TV room.
Any properly operating feeder with two conductors has equal and opposite
currents in the circuit thus, canceling fields radiating any distance from
the feeder. Now, it is far more common to have a radiating coax outer
shield at HF due to use of critical quarter wave length odd multiples of
feeder length, and lack of balancing coupling at the junction of coax and
the antenna.
Stuart
K5KVH
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