[Elecraft] RE: Dumb mistakes I have made

[Dave Benham]

The dumbest thing I ever did (other than buying a Gotham V80), radio-wise
(unwise?), happened when I was a novice at about 15 years old (in 1960).  My
first rig was a DX-40 transmitter that my dad had bought for me used from
Duffy's in Detroit.  I could never get it to work correctly.  I didn't have
an elmer -- my dad was an engineer, but not an EE and there were no local
hams to help me with things like this.  I screwed up my courage and grabbed
our Heathkit VOM (the second kit that my dad and I had built together --
probably the first VOM that Heath ever sold) and started probing voltages.

I had the DX-40 powered up, upside down on this behemoth workbench which you
could probably pound with a sledge hammer and not budge it.  This VOM had
two probes, each with a point for a probe tip -- no alligator clip for
ground.  So, I had a probe in each hand as I judiciously went around the
underside of the rig checking voltages against the Heath voltage chart.
Well, somewhere along the way, I figure in retrospect that about 600 VDC
went up one arm across my chest and out the other arm!  All I felt was a big
buzz!  In a reflex action, both arms jerked backwards, in one swift motion
dragging the rig onto my lap, hot tubes pointing down onto the tops of my
thighs.  The second reflex action, now that the voltage was gone, was
tossing the upside down DX-40 onto the floor.

Fortunately neither I nor the DX-40 were hurt.  My arms looked like they had
prickly heat for a while.  The DX-40 was a little bent and twisted, but
hammered out nicely on the old workbench.   The serendipitous moment in all
this was when I discovered that the crash landing had broken loose a cold
solder joint to the chassis where about a dozen wires were supposed to be
soldered to ground but weren't.  After heating that joint up and applying
some fresh solder, the rig worked fine.

Later I learned that the VOM's impedance was about 1000 ohms/volt.  I'm
still not sure how the voltage got to me -- I probably was touching those
pesky little set-screws in the probe handles that held the probe wires in
position.

Lessons learned:
1)   Keep one hand behind my back when dealing with equipment with high
voltage
2)   Use a VTVM with high impedance
3)   Don't use probes with set-screws
4)   Have someone within earshot to help you in case of a problem

Dave   K8TRF