[Boatanchors] A "Glow tube (VR tube) question.

[Philip Atchley]

Hi,
I have a Hallicrafters SX-71 that I completely overhauled/re-capped a couple
years back.  It has had "many" hours of reliable operation ever since then.
However, recently I've noticed that sometimes, not often, I'd get little
bursts of static or a crackle out of the speaker when I have the BFO on.  To
date I've been unable to locate the source as I could never duplicate it
when it's on the bench (always the case in an intermittent).

Anyway, I digress.  When listening I leave the lid propped up a couple
inches for better ventilation (runs a lot cooler.  Last night I was
listening to Shortwave and heard a brief "crackle" from the radio, sounded
like regular static.  I "normally" wouldn't think much about it figuring it
was atmospheric.

However, I "thought" I saw a small flash of light inside the receiver out of
the side of my eye.  I looked into the top of the set and saw the VR tube
(VR-150/0D3) was glowing OUTSIDE the plate, towards the top of the tube.
Not a big section glowing, but on the outside none-the-less.  The NORMAL
pinkish/purple glow inside the tube's plate was still there.  After a couple
moments the outside quit glowing and everything looked normal again.  This
abnormal glow DID NOT seem to have any apparent effect on reception (set
didn't drift in frequency).

QUESTION.  I don't think I've seen a VR tube do that before (glow on the
outside).  Is that indicative of a VR tube failing or should I look
elsewhere for a problem (like high B+ etc)?  I don't have a spare VR-150/0D3
to try out at this time.


73 from the "Beaconeers Lair".
Phil, KO6BB

DX begins at the noise floor!
Merced, Central California
37.18N  120.29W  CM97sh