[Milsurplus] Lamp 991 re-fire

[Mike Feher]

Some time back John Forster needed a 991 and I sent him one that I checked
out and it fired at its intended voltage for me. I never did hear back from
John if he even received it, or let alone if it worked for him. Glad you
shared that remedy. Regards - Mike

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960




-----Original Message-----
From: milsurplus-bounces at mailman.qth.net
[mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of John Hutchins
Sent: Saturday, March 27, 2010 9:32 PM
To: Milsurplus at mailman.qth.net
Subject: [Milsurplus] Lamp 991 re-fire

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