[Amps] Parasitics & Filament Sag

[Peter Chadwick]

Bill said: (re 6AG7)
> It was originally designed as a resistance-coupled amplifier for video output circuits
in the early black and white TV sets<
I think it was out shortly before the end of WW2 as a video amp/driver for radar purposes - a very similar application. Its little brother is the 6AC7. Funnily enough, I've never had parasitic problems with the 6AG7, although I've always used a 47 ohm grid stopper and 68 ohm screen stopper, with no shunt coils.
Thinking back, I can't remember any 813 PAs that had parasitic suppressors, although that doesn't mean that they may not have needed them! This includes a number of commercial (as opposed to intended for amateurs) HF tx's.
73
Peter G3RZP