Restoring a vintage radio receiver has the potential to be a fun weekend project, but it pays to know what you’re up against. Especially in the case of vacuum tube electronics, running down gremlins in the circuits isn’t always a straightforward process (also, please mind the high voltage that is present in old vacuum tube equipment). [Mr Carlson] has a knack for getting old radios humming once again, and his repair of a 1960s General Electric barn find radio receiver is a thorough masterclass in vintage electronics servicing.
Seriously, if you’ve got a spare ninety minutes, the video (after the break) is a thorough and unabridged start-to-finish diagnosis and repair of a vintage radio, and an absolute must for anyone interested in doing the same. This barn find radio was certainly showing its age, and it wasn’t long before in-circuit testing found an open filament in one of several vacuum tubes, but the radio was still stubbornly silent. Further testing revealed that the IF transformers were out of spec, requiring servicing and alignment. After fine tuning both the IF and RF sections of the radio, things were definitely looking (and sounding) better.
Fine tuning the various components in the radio went a long way to living up to its “long range” claims, and by the end of the video, it’s almost impossible to find dead air on the AM dial of this radio. If you’ve never had to make fine adjustments to a receiver, especially of this vintage, this video has all the details you’ll need. With the board exposed, [Mr Carlson] also took care of some preventative maintenance, including replacing the original filter capacitor with newer components, as well as replacing the mains safety capacitor with an even safer modern alternative.
We can’t get enough of these restorations, so make sure to check out our detailed write-up of restoring a WWII aircraft radio.
That’s really cool, kudos!
By the way, to who ever reads this comment and wonders what to do with an AM radio in 2022 :
These AM radios can be used for much more than just medium wave reception.
With an external AM modulator (low power transmitter), it can be used as a beautiful reveiver for web radio, for example.
That way, the internal receiver can be left intact.
Or, you can attach a band converter to the antenna input.
Back in time, there were converters from CB band to medium wave, which were made for car radios.
They still can be used today.
But that’s not all. There also were converters from 40/80m band or 10m band to medium wave.
FM signal reception is also possible with an AM radio.
Due to its selective nature. Just detune a bit from the center frequency – if you’re an ex-CBer, “Delta tune” may ring a bell.
In fact, many early FM radios were AM circuits really.
And if we add a BFO to it, reception of SSB/DSB and CW transmissions is possible, as well.
I don’t care for those old series tube radios and that brand more so as well as long videos. I did look forward to see to my surprise that it has a RF stage with 6 tubes instead of that “all American” 5 design. So the long distance label is not jive.
My first free pick up as a kid was one with only 4 tubes and no IF stage. 2 locals bled together and WLS got hit by our pre-NPR Purdue station. No wonder it hit the curb still working. I’d have respected this radio back then, the same design as a car radio. My second radio then was a tube car radio that I ran from a toy train transformer.
One thing I found back then on such cheap printed circuit board mounted tube sets was that solder joints didn’t make good support for hot tube sockets, tubes belong on a chassis.
OK I’m old I remember repairing this exact model of radio. at a repair shop that I worked at, It hummed (filter cap) Shorted tubes could hum too, but it was a different hum. Admittedly it was a repair , most of the parts still worked, not a restoration, in which case most of the parts don’t.
I would not have thought of using WD40 as a cleaning fluid.
Now, for a real challenge, replace the vacuum tubes with FETs!
I’ll bet it wouldn’t take too much more than dropping the plate supply to something an FET would tolerate.
This is an engaging report by a good restorer.
The presentation could be improved by editing. It’s about twice as long as it could be. There’s no need to say the same thing three times in a row.
The “l” in solder is silent.
Both pronunciations of “solder” are correct. Pronouncing the “l” is optional according to regional variations: https://www.circuitspecialists.com/blog/solder-not-sodder-the-story-behind-the-silent-or-not-so-silent-l/. I switch between the two pronunciations without even thinking about it, probably because I’m Canadian, (strong British influence), but grew up in a border town watching American TV and listening to American radio.
Solder is one of those words. I forget how I pronounced it, but I first saw it at age ten, and it was a few years before I ever talked to anyone on the topic. So you make guesses about pronunciation. It’s only with time that you hear the word and then “oops, I was doing it wrong”
Don’t Americans pronounce it “sooder”? Is that a regional thing?
I watch it at 2X speed, and turn on the captions. And skip around to the interesting parts (if any).
I noticed that he used rubbing alcohol to remove the sticky stuff from the top of the case. I use isopropanol a lot for that kind of thing, but when I’m faced with an unfamiliar plastic my first choice is lighter fluid because I find it’s less likely to melt the plastic or dull the finish. (I find WD-40 to be quite similar, but the lighter fluid smells less). If I’m at all unsure I’ll test my solvent of choice on the inside of the case first.
I also noticed that he started rubbing immediately. I’ll sometimes soak a piece of paper towel in solvent and apply it to the area for a few minutes, covering it with a bit of plastic wrap or foil if the solvent is particularly volatile. To do this you have to be quite sure that your plastic isn’t soluble in the solvent – experimentation and experience are the keywords here.
Another technique suitable for some gunky residues is to apply a strip of duct tape over it and peel it off. This will often remove at least some of the sticky stuff and make subsequent cleanup easier.
Ohw Dear. This reminds me I have a Marconi R1475 receiver waiting for an adjustment session. beautiful build radio.