>>
>>Rich says:
>>
>>>So when are amplifier manufacturers going to get off of their lazy
>butts
>>>and start building amplifiers. with a filament adj. rheostat and a
>means
>>>of measuring filament potential?
>>
>>I guess they don't because of number 1, cost, and number 2, the
>capability
>>of allowing people to wind up the volts - 'gee, Wilma, you get more
>output'.
>>
>>Better, but even more expensive, is a regulated filament supply that is
>>current limited so the inrush current can't exceed twice the normal
>current,
>>and doesn't vary with line volts. You can afford to build that sort of
>thing
>>into a home brew amp.......but commercially it's a no-no.
>>
>>73
>>
>>Peter G3RZP
>>
>Heaters are soft-started with a motor-diriven variac,
Heaters are a different ballgame than filaments. The typical filament
has 1/8.33 as much R when cold as when hot. This is assuredly not the
case with heater types. I know of no Eimac heater type tube where slow
starting a heater is advised. For the larger filament type tubes, slow
starting is recommended.
cheers, Mark
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