I had the same behavior in my early serial R4-B. It's quite a light show in a darkened room. The cause is definitely a bad VR tube in which there has been air ingress. Just stick another tube in there.
Dennis AE6C On Mon, Mar 16, 2009 at 7:24 PM, Garey Barrell <k4...@mindspring.com> wrote: > Well, it's obvious that the "original configuration" is obsolete and needs 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 >> >> > _______________________________________________ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist >
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