[Milsurplus] Restoration Ramblings (was Rethinking Re-Capping)

[WA5CAB at cs.com]

I'll throw my own half century of experience into the FWIW column.  First, 
although I have had quite a few BC-348's through here over the decades, I 
have never actually worked on one.  But I still have quite a bit of spare 
parts for them.  Plus I've never worked on any SP-600 but a lot of SP-400, 200 
and 100.  The only thing that I can say about Sprague Balck Beauties is that 
I had a box full of unused ones of various values and voltages and all were 
bad.  Otherwise, I've worked on a lot of WW-II and Korean War vintage sets 
from BC-611's to BC-610's, a fair number of Navy receivers and a few VRC-12 
family mostly in or around Vietnam.  My general experience is that once in a 
while you'll run into a set where every capacitor in it is electrically 
leaky, including the oil filled metal can ones.  I once encountered a BC-342 in 
that category.  And I think one BC-221 out of the roughly 50 that I have.  
Beyond that, my rule is to check any capacitor which if it shorts can take 
out something harder to replace (fortunately there are few sets in that 
category) and then to light the set off.  If I find a bad capacitor, I change it.  
If I find a second one of the same type, value, voltage and contractor, I 
check one or two more at random and if bad then replace all of that 
particular one.  And I don't use orange drops or other radial lead components in 
place of axial lead ones.  When I find one in a set, I immediately suspect and 
search for other hacking.and all too often find it.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 12/03/2017 14:27:44 PM Central Standard Time, 
ark at ar88.net writes: 
> First off, I want to thank Jim for the shout out re: The Radio Technology 
> Museum.  Our web presents is a bit schizophrenic, the link above shows 
> some nice pix with little else.  Here's our other website:  
> http://www.rtm.ar88.net/ which includes some dated pix of the WWII Tactical Communications 
> Display: 
>  http://www.rtm.ar88.net/Tac_Comm/Tac_Comm.html  There's twice as much 
> stuff on display now.  Do come and visit us if you find yourself at the Jersey 
> Shore.  Lots of other interesting stuff at InfoAge beside radios.
> 
> Our attitude, from the jump, has been that cold dead radios are not very 
> interesting.  So, we try to have working examples on display.  We have a 
> broadband LF-MF-HF antenna over the building that feed a TMC distribution 
> amplifier that feed the display radios, via coax.  We also have a low-power 
> transmitter feeding old-time music on 1080 KHz into the distribution amp.   So 
> while most of the sets sit on our local sig., and any of them can be tuned 
> to actual stations off the air.
> 
> Two of my restored sets, a slightly ham-hacked BC-348 and a 1936 GE A-82 
> tombstone, have been playing without incident, three das a week for about 10 
> years.
> 
> Restoration:  See the video:  https://www.youtube.com/watch?v=_OYw2wfdSCs&
> t=3s  That's me as a kid 20-some years ago.
> 
> Some specifics on the BC-348:  I replaced the power supply filters, it had 
> an AC supply built in.  I replaced ALL the 0.1 uF Micamolds,  I left the 
> rectangular metal cap in place.  That's it.  It's played well for a long 
> time, and I've restored numerous radios with similar techniques, getting 
> similar results.
> 
> BTW, the GE A-82 is a nice all-wave set, and was one of only a few 
> broadcast set advertised in QST, Dec 1935, p87.
> 
> Yes, there are some rare and significant radios that probably shouldn't be 
> touched.  E.g. the AR-11 "Compact Transceiver for Covert Action," i.e., 
> spy radio in our shortwave display.  (One recently sold on Ebay for almost 4 
> grand.)
> 
> My two cents,
> Al
> -- 
> Al Klase – N3FRQ
> Jersey City, NJ
> http://www.skywaves.ar88.net/
> 
>  
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