Many years ago, as in the 50's I took a correspondence course on
electronics. One of the first things we did was build a volt meter. A
few years later I needed to check the plate voltage on my HT-44 power
supply. If any on here remember that series, you measured the current
across a resistor in the PS150. The ends of the resistor are connected
to meter jacks so you can just plug in the Simpson or what ever meter
leads. The voltage is in the neighborhood of 500 volts plus change (570
IIRC). At any rate I had to get up on the operating desk and reach
cross armed over to the meter. Unbeknownst to me, my fingers had slid
down to the probe tips although I didn't feel even a tingle. I didn't
feel a tingle that is until I reached over to pick up the meter which
had a metal, grounded case. In one arm and out the other. I woke to
find myself laying on my back on the tile covered, concrete floor. I was
as out of breath as if I had just finished a marathon. I worked my way
up into the big easy chair and sat there for about a half hour
contemplating why I was still alive while I Also waited for my breath to
catch up.
I had pitched head first off the work bench to land on my back which
probably started my heart again or at least I think that is why I was so
out of breath. Then I was also lucky the fall didn't break my neck.
There were burns on the ends of my fingers on the right hand and
matching pits in the PS chassis. To say my arms and chest were sore the
next day would be an understatement. IIRC it didn't even blow a fuse.
To top it off, a few years later, after moving to the old family farm
and building a new home in the Breckenridge MI area I had something
similar happen, but not by grabbing a PS.
I had a 1/4 wave, 40 meter vertical in the West yard. The shack was
located in the SE corner of the basement making it a good 120 to 150
feet from the vertical. At the base of the vertical was an 8' ground
rod with bare copper radials fastened to it using a pipe clamp along
with the coax shield. One of the radials had come loose. I bent over and
picked it up, pulled it tight, and kneeled down to push the end of that
wire which was grounded at the other end. As soon as my knees touched
the damp soil It had me. Fortunately I was balanced on the balls of my
feed and tipped over backwards. As soon as my knees broke contact it let
go and I THREW the wire as hard as I could.At least I stayed conscious
so I could enjoy getting my battery charged.
The station was grounded, but the old Yaesu FT-101B used a two wire
power cord. An over generous solder joint (from the factory) allowed the
hot wire to contact the chassis. As this was before ground fault outlets
and circuit breakers were common probably the coax shield was carrying
the majority of the current as the ground directly behind the station
was higher and dry. I took my Simpson 250, laid it on the ground and
reached out as far as I could to place the probes directly into the
ground. One was about a foot from the grounding rod at the base of the
vertical and the other about 5' to 6' out. I measured over 100 VAC.
The station was tied into the house electrical ground so why it didn't
pop the breaker? I don't know.
Even the lower voltages can sneak up on you and if the contact is good
the results won't be.
73
Roger (K8RI)
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