Best Tube Transceiver?

John Kolb jlkolb at CTS.COM
Sun Mar 28 14:02:15 EST 2004

On Sun, 28 Mar 2004, edoc wrote:

> The SB-101 sounds interesting, I will check it out.
> I suppose I do not have to use the matching power supply,
> there must be something with the same specs that is 100% non-semiconductor.
> I'd hate to go through all of the trouble of acquiring
> and optimizing a no-semiconductor rig only to have
> something in the power supply fuse in the face of EMP!
> OR, is it fair to say that the semiconductor devices
> used in the matching SB-101 supply are of such high
> tolerance that indirect EMP won't bother them?

While solid state diodes are much more rugged than transistors,
their ratings fall far below the possible voltage peaks
of an EMP or other event.

Once had a neighbors rusty TV antenna fall on 14 KV power
distribution lines. The resulting voltage spike blew a light
bulb - turned off at the time - out of it's socket, embedding
shards of glass and molten solder into the ceiling above the
fixture. 3" of PC board etch vanished inside a tape recorder.
Never underestimate the power of a voltage spike.

I have lots of MOV's scattered around the house across the
power line - in many different power strips, radios, etc.
Hope the overall effect will control any surges. Sounds better
than depending on a single one at the point of entry.

It wouldn't be a lot of work to build a power supply using
5U4's, etc to go with the SB-101. Or just stock lots of spare
diodes, knowing it would be easy to identify and fix the problem
if they fail. I'd put fuses between the transformer secondary
and the diodes - much better protection than depending on the
primary fuse to fail.


This list is a public service of the City of Tempe, Arizona

Subscription control -
Archives -

More information about the Boatanchors mailing list