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Re: Snow on telly, help needed !
I would would submit the possibility that somehow in the structure of the
primary circuit (i.e. the primary coil, cap, and spark gap) you have created
a parasitic oscillator in the VHF or UHF frequency range. Terry Fritz
address this to some degree on his web site. In addition to his suggestions,
I would suppose that the use of a RC snubber across the primary coil (or
possibly spark gap) could be used to squash the Q of the parasitic resonant
structure. It shouldn't take much C since TVI frequencies are realy high
compared to the coils resonant freq.
I would try some plates several square inches in area separated by some
descent plastic insulation in series with a couple watt carbon comp resistor
of a value in the 10's to 100's of ohms. Copper foil strips or pipe would be
preferable to connect this setup(low L). If you know the frequency of the
parasitics you could calculate values to squash it. Of course sometimes
shootin' from the hip can work pretty well too;^)
Eddie Burwell