The inevitable callback on RCA 17PT8072

[Phil Nelson]

The luminance delay line is a thick cable-like component mounted above the chassis. The schematic shows two components (L62, L64), described as "filament choke," between the filaments of the IF tubes. I haven't tried to sort things on the foil side to determine whether these squiggles are indeed the chokes. Filament choke is a new concept to me -- maybe intended to filter AC ripple to keep it out of the video signal?

Phil Nelson

[dieseljeep]

I had a simular model that had a transformer power supply and a 5U4 rectifier. I lost interest in it, when I discovered, that someone hacked up the PC board, in some kind of a repair attempt.
Some of those RCA's were pretty impressive, buy miserable to repair.

[old_coot88]

Originally Posted by Phil Nelson

...The schematic shows two components (L62, L64), described as "filament choke," between the filaments of the IF tubes. I haven't tried to sort things on the foil side to determine whether these squiggles are indeed the chokes. Filament choke is a new concept to me -- maybe intended to filter AC ripple to keep it out of the video signal?

They're RF chokes intended to avert spurious coupling problems (ie., feedback) via the heaters.
Never heard it explained that way, but presumed that's what they were for.