Re: Hallicrafters S-38 lack of sensitivity on the HF bands

COLIN LAMB wrote:
The GFI breaker in my basement shop drives me nuts.

Yes, they can be a pain in the ... But better that than something shocking. The isolation transformer is a good idea, although the ham I mentioned about from the 30's was killed in a transformer operated rig, when the ac shorted out to ground in the transformer.

An isolation transformer is a good thing, but if you want to use one, you
need to ground something to make it a safe thing. Leakage in the run of the
mill transformer is uneven from one side of the secondary winding to the other.
It has to do with the winding mostly progressing from inside the core outward.


Construction of a small box with a GFI outlet to only power a few items such as the S-38 might be one alternate approach.

When in high school, I got my hand across a 1500 volt power supply and was picked up and thrown across the room and knocked the doors off my closet. I was dazed but unhurt. It knocked sense into me, and I have been afraid of high voltage ever since. I now short things out two or three times before working on high voltage and then still do not trust it. I have now gotten to be pst middle age without any further shocking developments.

Back when I was a teen aged engineer, I built a nice regulated HV supply.
I (for reasons that elude me now) made the supply with the HV side isolated
from ground... I think I wanted to be able to go negative WRT gnd if necessary.
My bench was powered by a 2 wire extension cord... no bond wire.

Well, I didn't think some things out quite carefully enough. I had the filter
caps clamped to the chassis. The filter caps guts were isolated from their
aluminum can, and I didn't check to see how good of a job they did with the
isolation. One of the caps developed a short from its + terminal to the
aluminum case... putting the chassis of the supply at +800V above the - terminal,
which was chassis ground on the transceiver I was testing... I was tuning
the rig up, and I had my right hand resting on its chassis, with a diddle
stick stuck somewhere, when I smelled something hot. So I reached over with
my left hand to flip the metal handled power switch on the

p__o__w__e__r____s__u__p__p__l__y...

The 800VDC arm-to-arm caused a violent muscle contraction, and I threw myself
back about 8 feet into a cement block wall. OUCH! Apparently, I did wake up
afterwards....

I don't isolate *anything* anymore. It gets grounded period.

-Chuck Harris
.

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