I agree entirely with Ed Hare's comment the other day, that an LPF on
the end of an HF transmitter will rarely help cases of TVI, unless
there is something wrong with the TX. The use of LPF's springs from
the days of TV in the 40-50MHz band, when harmonics from our HF bands
did cause problems which a LPF could prevent. The main reason for
using a LPF these days is to show you are doing your bit.
I find that braid breaker type HPF's at the TV aerial input to be
very effective in stopping breakthrough from HF. There are very easy
to make, and a suitable design has been published by the RSGB.
73 Fraser G4BJM
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