*(1) An intermittent that shows up after an hour or so that causes signal levels to drop about 20 dB for a few seconds then pop back in. A burst of static, switching to STBY and back to RCV, or opening up the bandwidth to cause a "burst" of signal will correct the drop, but then after several seconds it will drop again (but it self-corrects, the drops, then self-corrects.....most annoying).*
I don't know which tube it is for your receiver but try a known good voltage regulator tube. In my TR-4 it's something like V20 = 0A2. Good luck. On Thu, Sep 23, 2010 at 12:15 AM, <ph...@aol.com> wrote: > Finally got one of the three R-4A receivers working well and it's now > in the shack. Here's the status: > > R-4A #3781: A 13-tube, the second-nicest of the three, re-capped and now > working just fine. The only issue with this one was a REALLY warbly PTO. > Since #3735 (see below) was quite stable I swapped out PTOs and got 3781 > checked out & fully aligned. > > R-4A #3735: Another 13-tube and the worst of the three (the chassis looks > REALLY bad, chicken coop storage?), this one has a thoroughly hosed-up > preselector drive that I need to rebuild including turning a new SS center > shaft on the lathe. It also now has a warbly PTO (see above) but before I > swapped out the PTO it worked fine except for the preselector drive. The > chassis will make a good test-bed for trouble-shooting & fixing the PTO > assembly. > > R-4A #5757G: An 11-tube, this unit looks almost new inside and out and a > chassis this clean has got to be VERY rare. Unit has been fully re-capped > and after a 30-minute warm-up it aligned just fine. It works great except > for two things: > > (1) An intermittent that shows up after an hour or so that causes > signal levels to drop about 20 dB for a few seconds then pop back in. A > burst of static, switching to STBY and back to RCV, or opening up the > bandwidth to cause a "burst" of signal will correct the drop, but then after > several seconds it will drop again (but it self-corrects, the drops, then > self-corrects.....most annoying). The drop is visible on the S-meter as > well as being audible. Tube replacement doesn't do a thing for > it. Replacing the damaged tube socket for V4 didn't, either. > > (2) Seems to have a little distortion in the AM audio. Haven't searched > for the cause yet. > > > 2B #2052: Has worked great from the day it arrived and I haven't had to > touch it. It's due for a re-cap (kit is on hand) and I'll run through the > alignment, and since it lost its place on the operating desk to R-4A #3781 > tonight I'll probably tackle it fairly soon. It shouldn't need much other > than the new caps. > > Problems notwithstanding, it's pretty amazing that these 40+ year-old > receivers can be made to work so well after all these years. > > 73/arf, > > Paul, K4MSG > > _______________________________________________ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist > >
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