Ron Wagner <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Gary,
I looked at this some years ago. I had a design started that would drop
the filiament voltage off the rig. Kind of hard to run a tube w/o a
heater. You would have a 2-3 second delay looking for bias voltage, and
if not there relay off the filaments. Looking in the rig would quickly
tell you what was going on. I kind of like to play with the low voltages
myself.
73,
Ron WD8SBB
On Sat, 15 Dec 2007, Garey Barrell wrote:
Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Mike -
Yeah, it's not as easy to crowbar a 700V power supply as it is a 13.6V one!
Probably simplest is a thyristor across the AC line (after the fuse! :-) )
and drive it through an optocoupler from the bias supply. An R/C delay on
the coupler to give the bias supply a few seconds to come on, and after that
if the bias drops to x volts POP! It really shouldn't happen but once, and
a fuse is cheap compared to finals, etc.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Mike Bryce wrote:
Mike Bryce <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Gosh..
I thought about that, but here's no way to crowbar the bias circuit.
in the old supplies, the damage is caused by a "lack" of bias. So, if there
is a failure of the bias supply, i.e. it quits, how can you fix that?
the only way I could come up with would have been a system that deprives
the transformer of it's primary voltage, shutting down the supply. It would
have to default in the off position too, as you would not want the supply
to cycle on, find the missing bias, then shut down, the power up, find the
missing bias supply, shut down and on and on.
mike
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
J e e p
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On Dec 15, 2007, at 5:28 PM, Bill Horne wrote:
Bill Horne <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Is there a provision in the kit for a crowbar circuit to safeguard the rig
if the bias (or other) supply fails?
Bill, W1AC
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