[Amps] Speaking of filaments...& regulation

BEAR bearlabs at netzero.net
Tue Feb 4 11:55:46 EST 2003

> While the ferro-resonant transformer seems like a good idea
> at first--there are some issues.  The main thing is that they
> work at a single line frequency.  So you can't use only one
> transformer for 50 and 60 Hz.
In the USA, that's a moot issue. At my QTH, quite moot.

>   And they show reverse
> regulation with variable frequency line voltage from generators.
> Plus they are relatively bulky and expensive.
Not running on a generator... not likely to run a kilowatt on a generator, if I
have to
go to emergency back up power.

> A more viable solution -- is active regulation with a Triac
> and an RMS detector.
Like a motor controller? So you're controlling in effect the duty cycle of the
sine wave?
Any schematics out there?? I'm interested in the idea. Anyone tried this or done
with filament voltage control?

> But this means that the vast majority of hams would have to
> pay for something they don't need just to aid the few that
> have out of spec AC line regulation.
Few? How about almost everyone has out of spec line regulation?
Pay for? I'm talking DIY!

Around here the line voltage can move around with the season, in the summer it
on the worst days with the time of day... or squirrels on the pole pigs.

Although *most* of the time it is pretty stable, dorking a pot or variac
the line voltage moves is not a really good solution since you have to *notice*
that the line voltage has moved enough...

I've got motorized dual 20 amp variacs, I could get a meter relay and set up
low limits and use that to drive the motor to keep the output voltage within a
predetermined range... as a "simple" solution. But I think this is like swatting

a gnat with a sledghammer.

> Life is a balance between what is realizable and what is
> affordable.  Get used to it.    ;-)
John, we're talking around here about an Alpha amp that is so heavily computer
that it has shut itself down... so the range of affordable and realizable seems
broad. Not to mention PIN diode switching, DIY aftermarket controller boards,
dynamic tube biasing, etc...

> John   W0UN
            _-_-bear WB2GCR


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