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Reviving an S-38B -or- Jumping into the Deep End

Tube Era Tuner

New Member
Jul 30, 2022
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If you look at my avatar, you'll see the almost pristine Hallicrafters S-38C that I inherited in the wake of my brother-in-law's tragic and sudden death from cancer. I'd always been interested in shortwave, but never took the initiative. This changed almost overnight. So now I'm spending an evening or two a week swiveling a ceiling-mounted MLA-30+ and tuning in Radio New Zealand and Radio Havana and whatever else comes in. I'm hooked.

I posted about this on Facebook, and through a series of conversations I ended up being gifted an S-38B. I'm thrilled to have it and am looking forward to fixing it up. There are just a few problems...

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This poor thing is the victim of both neglect and abuse.

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The original 5" speaker is long gone, replaced by a 3 x 5" speaker bodged into place with sheet metal screws. Of course, the cone is a wreck and it doesn't work.

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The radio was apparently dropped on its face, punching the power / volume switch into the case.

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Other than that, the innards appear to be largely intact and unmolested...

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...except for this detonated resistor that's attached to the AM / CW switch. What could have caused this?

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First thing to be done will be to vacuum out a bit of dust...

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...and maybe use a lathe and some 1/4" Delrin rod stock to replicate a pair of these rods, both of which have fractured (the other one is completely missing its end).

So... a fun and educational project, no doubt. I plan to replace all of those volcanic capacitors, of course, and the badly rusted case will get stripped and treated to a fresh coat of paint. I see there are both water decal and dry transfer options regarding the graphics. I have previously fabricated bottom and back panels out of polycarbonate to show off the "warm glow of electric sex" workings of tube radios, and will most likely do the same with this one. Since the knobs are all missing, I may opt to go with some retro but non-stock alternatives. Same goes for the paint finish (hammertone emerald green, perhaps?). Lots of possibilities.

The only daunting issue is that I know essentially nothing about electronics. I'm a broadly talented electro-mechanical engineering technician with decades of experience. I earned an IPC J-STD-001 soldering certificate (with space addendum) while working at NASA and building experimental packages that were flown to the ISS. I can do machining and sheet metal fabrication and rebuild just about anything mechanical, but my brain just doesn't seem wired for electronics. I understand electricity on a "plumbing analogy" level, but still can't figure out how a combination of resistors and capacitors and diodes work to convert electromagnetic waves into audible sound. So I'm probably going to be asking a few questions...
 

Sorry to hear of your Brother’s passing. This would be a darn good way to remember every time you use it! I ended up with a working National NC-183. Have the cap kit for it, but need to take the time to install it.
 
I would recommend buying an isolation transformer to reduce the shock hazard. This is a "hot chassis" radio that has no transformer in it to isolate the wall socket from the chassis. Clever use of capacitors makes the chassis a ground for RF but not for 60 Hz AC.

On a good day, downhill and with a tailwind. In the real world, there is always enough 60 Hz AC leakage current to give you a small "tingle". And if a capacitor goes bad, "ZAP!". This model's power draw is not a lot, so a small isolation transformer should not be terribly expensive. Considering the potential shock hazard, it's cheap insurance.

73
 
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