[AMPS] filament rheostats

[n5ar]

I have been using the Triac soft start wall switch unit as the filament
switch in an amp which used 4-1000 and later an 8877 for 15 years with no
problems. I am surprised that more people aren't doing this.

73, Dan , N5AR

Mark Marsden wrote:

> >
> >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, or
> get a step-start supply, but has anybody seen or tried
> slow starting a heater using a triac and PWM control?
>
> Mark G4AXX
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