On Wed, 07 Jan 2004 03:15:02 GMT, Larry W4CSC wrote:

Foldback current limiting assumes the pass transistor doing the
folding back is a functional device, not welded from E to C....(c;

On Tue, 06 Jan 2004 15:30:54 GMT, Larry wrote:

On Tue, 06 Jan 2004 06:18:18 GMT, Larry W4CSC wrote:

On Sun, 04 Jan 2004 16:10:10 GMT, Larry wrote:

On Sun, 04 Jan 2004 03:18:07 GMT, Larry W4CSC wrote:

...snip

Junk it. I did mine. If that damned series pass transistor ever
shorts, you can kiss all your equipment hooked to it good bye when the
20-some volts hits them.

You probably know this, but you can (actually, must) prevent that happening
by putting a "crowbar" circuit across the output, after the fuse. This is
just a large scr with a resistor from the bus to the gate with a 14 or 15
volt zener to ground. It doesn't conduct until the voltage exceeds the
zener limit and then the scr shorts to ground, blowing the fuse and
protecting the equipment.
--

Larry W1HJF
email is rapp at lmr dot com

Oh, I know. Does it have an output fuse? Mine didn't, just the AC
line.

The Astron 40 I just checked didn't. I added one in series and stuck the
crowbar after it. It does have foldback current limiting, but that won't
necessarily protect equipment connected to it.
--

Larry W1HJF
email is rapp at lmr dot com

Good point!
--

Larry W1HJF
email is rapp at lmr dot com