>has anyone done a tube conversion on a 78 ?
>
>I have been told it is a real pin in the a** .
>
>I know it will devalue the amp but I plan on holding on to it for a long time
>
>I was thinking about using/converting it to 3cx800a7's.
>
? As I understand it, the larger anode cooler diameter limits it to two
3cx800s. The larger coolers also requires moving the sockets farther
apart. Since the 78 has no tuned input, I would consider using 4cx800s
in AB1. The screen current needed is so low that the anode supply could
easily power a zener-string shunt regulator for the screen. However,
'tis best not to dissipate more than 1/3 of any zener's [25ºC-case]
dissipation rating because the case is not going to be 25ºC in the real
world.
>
>Im thinking it would be cheaper to convert it that to buy 3 new 8874's
>
? If you have some kaput 8874, I would like to autopsy them and
photograph the guts. Name your price.
>
>Thanks
>
>
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
end
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