Well, it's obvious that the "original configuration" is obsolete and
needs to be replaced by a piece of silicon!! :-)
Actually the flashing in VR tubes is often seen with leakage of air past
the pin seals. I have had several NOS tubes that have exhibited this
behavior. You may need to try more than one or two to find a good one.
Cold ambient temps cause momentary flashes at startup, as does high
voltage from those pesky solid-state rectifiers that apply HV before
the tubes warm up enough to pull the B+ down from the peak value. But
generally it's air.. Guess these would be "airy" tubes, as opposed to
"gassy" tubes. :-)
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>
Curt Nixon wrote:
Good Afternoon All:
Here is something I have been seeing now for a while. In my R-4a, every
cold start in the morning, the OB2 flickers and glows VERY bright. From
an angle, it looks like there are flames on the inside of the rcvr. I
almost spilled my coffe all over trying to get back to the switch the
first time I saw this.
It will go on for quite some time and eventually die down to the normal
red glow. If I cycle the power a couplle of times, it will usually stop
and show a normal glow on the second or third restart.
I originally thought it was because of relatively low morning temps in
the shack..about 55 degrees, but it seems there is really no corelation
to temperature--occasionally after running for 6-10 hours, it will just
start the really bright flickering.
I have replaced the OB2 and checked all components and voltages around
this area and they are all proper.
The radio has been re-capped and all PS voltages are nominal.
There is no detectable noise or other performance change while this is
ocurring that I can tell but in 40 years of ownership, this has only
been happening lately.
Any Ideas??
Thanks
Curt
KU8L
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