[Milsurplus] [Boatanchors] R-388

[Robert Downs]

Howie,

After reading your first three paragraphs, my thought was that the problem sounded like missing or leaky decoupling capacitors.  I've not had that problem with my R-388 so I didn't know that they were red.  

Robert Downs


-----Original Message-----
From: boatanchors-bounces at mailman.qth.net [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of howard holden
Sent: Friday, May 25, 2018 7:35 PM
To: boatanchors
Subject: [Boatanchors] R-388

Started working on an R-388 two years ago, then life got in the way. Getting back to it, and the old girl�s coming to life.

I�ve cleared up some issues with loose/misaligned cams on the IF slug rack and slippage on the drive shaft that moves the IF gears, reset the drum pointer and dial so that X.100 Kc appears where it should. Tracking on the VFO seems pretty tight.

Aligning the IF, slugs seem to tune correctly, the caps seem to have relatively little effect. But reception is pretty good on the 2 and 3 Mhz bands. Aligning the RF (4-7, 8-15, and 16-30Mhz) same situation on the 4-7 and 8-15 sections, but the 16-30 section adjusts well on both slugs and caps.  Also reception is good on 4 Mhz, fair on 5 and 6, poor on 7, good on 8Mhz, fair on 10-13, poor on 14 and 15 Mhz. Haven�t REALLY made an evaluation on 16-30 yet.

I recall having seen info that the little red mica caps (on most of the RF and IF coil/cap assemblies but not present on the 16-30) can be an issue. Is this good sensitivity on the low end but poor on the high end caused by flaky red caps? Also getting the same effect on tuning the caps on the BC band, although that band seems to be working quite well overall.

Comments/hints/suggestions welcome!

Howie WB2AWQ/7

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