[AMPS] 6 volts on a 3-500Z filament

[William Fuqua]

   I got a single 3-400Z homebrew amp that someone had given up on.
I connected it to my power supply and fired it up. At first I thought the
tube that came with it was bad but I then checked the filament voltage.
It was almost 4 volts.  The guy used a 5 volt transformer but did not
allow for the drop in the filament choke.and wiring.  I simply added
a 24 volt boost transformer in the primary and that brought it right
to about 5 volts at the socket. I can now switch out the
boost transformer to extend the life of the tube when in standby.
I imagine the builder must have been frustrated not being able to
figure out why he could not get much output.

73
Bill wa4lav


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