>"1. Don't let your reach exceed your grasp. This is not a project for
beginners. You should not attempt to build [a high power amplifier]
unless you're a seasoned builder who has experience with high voltage
circuitry."
Great post by W8ZR. I developed respect for high-voltage almost
simultaneously with two projects: during construction of a 6DQ6A/OD3/5U4
transmitter at age 11 (oversight by my OM, W9EAC); and the repair of a
Hallicrafters SX-100.
In the first instance, the 6DQ6A was mounted atop the chassis, exposing the
flying high-voltage plate lead. Unknown to me was that the HV lead was
nicked to the conductor at a point just below the plate cap. With +750V
applied, I grabbed the insulated plate cap to "straighten it out." But I
also grabbed a portion of the wire that was nicked. My other hand was
touching the grounded chassis. That was lesson #1.
During the second instance, I was messing around with the SX-100's S-meter
circuit and didn't realize that roughly +350V was on the meter terminals --
I thought it would low voltage owing to the sensitivity of the moving coil.
I quickly found out why Hallicrafters placed a piece of fish paper across
the terminals. To this day, I believe that shock was the worst I've felt,
possibly because of sweaty hands. That one did throw me into a cabinet
across the room. Never told my OM about either event, figuring he would put
a stop to it all.
>"3. Never work around high voltage when you are tired, stressed, or in a
hurry. 4. Never work around high voltage after drinking alcohol. Even one
beer
or glass of wine can impair your judgment and make you careless."
Out of college, I worked in broadcast engineering and routinely worked with
plate voltages as high as 12KV. Often, this work occurred after midnight,
when I was very tired and didn't bring a support person as a safety backup.
In later years, I worked for stations in large markets that had funding for
alternate-main transmitters. Much of the preventive maintenance could then
be performed during the day. Many times, I would do this work after a
lunchtime beer. Back in then, lunchtime alcohol consumption at a restaurant
with a group of guys was very common. Looking back, there were many stupid
safety-related violations that I can only attribute to young age and a sense
of immortality. Many of us should be grateful we're still here to tell the
tales.
Paul, W9AC
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