From: [EMAIL PROTECTED]
> The plate transformer in a
> typical 1 kW tubed transmitter can deliver sufficient voltage and
current to
> run an electric chair. YOU COULD GET KILLED!
It isn't the voltage that kills, it's the current. You could get fried on
a
12V battery if it gets you in the right place. But interlocks were put
there
for a purpose and defeating them is dumb, risky, foolish, idiotic and down
right dangerous. For that matter, you can get fried wiorking on a receiver,
too!
"Switch to safety!"
Very true, and I would never rewire around the interlock. On my BC1-T, I do
sometimes use a thin washer to temporarily defeat the interlock, since
otherwise, with the front grille removed, the power is shut off to
everything. Even with the HV turned off, the exciter stage is killed as
well. That makes it difficult to take voltage measurements, or tweak up
circuits as needed. Of course, with the side or rear panels removed, the
interior of the transmitter, HV and all, is accessible regardless of the
interlock.
Working on these things carries the same hazards as a comparable homebrew
transmitter, and requires that you be alert and know exactly what you are
doing at all times. Interlocks, designed to add a layer of proctection
against carelessness, do sometimes fail since switches have been known to
mechanically stick and contacts to weld closed, so don't trust your life to
a properly functioning interlock circuit - there is just too much stuff
there that can malfunction. Probably the safest interlocks are those that
mechanically short out the HV using a spring loaded switch activated when
opening the door or removing the panel, but even those are not 100.00%
reliable.
On my homebrew KW, I built in an interlock on the door that is opened for
access to the plug-in coils, since these run with full modulated HV on them
when the transmitter is operating. I would never try to change coils with
the rig in TX position. The more redundancy the better. When I change
coils, the interlock is turned off, the rig is in standby position, the main
HV toggle switch is in the "off" position, and I have made it a habit to
observe the plate voltage meter to make sure it is at zero. A shorting
stick would'nt be a bad idea, either.
Don k4kyv
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