[Milsurplus] Lamp 991 re-fire
John Hutchins
olegerityincj at austin.rr.com
Sat Mar 27 21:31:50 EDT 2010
Good evening group -
Picked up a BC-348-O made by RCA. Condition very dirty, just covered in
dirt. Cleaned it up..... And yes brought the power up to 227V over 2
days, initially set B+ at 10V for 12 hours. Any how the 991
"regulator" lamp did not fire. I measured the voltage at the OSC line
at 110V-DC. Cleaned the contacts, inspected the bulb, looked in real
good physical shape. The 991 still would not fire. Then I remembered
that some one talkig about school where there electronics professor
would put Neon - Lamps into a plasma state by allowing high voltage and
current to flow through them making them glow a deep purple blue.
Who ever that was a darn good Idea! I got the Lamp to fire at 130V
It started off red then made a sound like a light bulb makes when the
filament blows, a light metallic rattle. The 991 works just fine. So I
thank the person who related that old school time story, It saved me
from ditching a perfectly good "regulator" lamp.
I wonder why it was so hard to start the 991 after sitting so long? Its
like the Neon had gone to a solid, had to be gassified.
-Later-
Hutch
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