In article ,
"Frank Dresser" wrote:

"Billy Burpelson" wrote in message
...

CAUTION! ---- SHOCK HAZARD!!!!!

You may or may not be familiar with the following:

The S-38s are basically 5 tube 'All American Five' radios that do not
have power transformers, but rather have one side of the AC line tied to
the chassis.

That's true of the original S-38, but early in the series Hallicrafters
switched to a seperate common bus wire and floated the chassis. I don't
remember exactly when the change started, may be with the S-38B. I'm
certain the S-38D had a floating chassis.


To add insult to injury, these radios have a METAL cabinet.

The only thing between the students receiving a severe (or fatal)
electrical shock is the 50 year old (read dry and crumbly) rubber
washers that Hallicrafters used between the chassis and metal cabinet.

The same thing could be said of an old lamp, especially a metal lamp.
What's to prevent a shock hazard? Just a roll of paper between the lamp
socket and the shell.


If you've not replaced these washers or put on a polarized line plug
(and checked for correct polarity on the wall socket), you have a
potentially large liability problem on your hands.

Actually, putting in a polarized plug, by itself, won't help much. The
power switch is on the volume control and transformerless radios typically
switched the neutral in order to reduce hum pickup from the hot wire. Even
with the radio switched off, the chassis can still be energized with AC
through the tube filaments. There's also an antenna coupling capacitor
which should be changed.


Great idea, but bad choice of receiver (IMHO)...

Anyone who can learn radio can, and should, learn safety.

And plugging these old radios into modern GFCI protected outlets would
provide a good margin of safety.

I was going to ask you what the earth ground was supposed to be
connected to for the GFCI but you answered it in this post. The outside
metal cabinet. This is fine with the radio assembled but what about
while it is being worked on outside of the cabinet and connected to test
equipment? The only answer I know of here is an isolation transformer.

You cab easily have potentials between the test equipment chassis and
the radio if the equipment is plugged into another circuit, and mention
you could have ground loops.

--
Telamon
Ventura, California