Making parts for an antique radio

Sound great!! Photos would also be nice :)

Regarding the dial .. if you don't know maybe radiodaz has a aftermarket one.

The load humming noise is a sure indicator of bad electrolytic caps or inside the canister condenser. Just my thoughts. I have also restored radios and as always replaced ALL caps and still had a hum until I found that my florescent lights was getting into the radio lol lol.

Looking forward to the outcome... now I'm back to my Atlas 10D lathe restoration.

Dave

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I recapped it (electrolytics). I started rebuilding radios, then moved on to test equipment. I'm away from my normal workbench so I don't have access to all of my toys (including my little lathe).

The hum was really bad. Actually... I think a put a short video on YouTube.

Yup, I did. -

It's not pretty but it's got audio of what I was hearing as I tuned across the AM band

The Antique Radio Forum (ARF) is a really good resource.


I have the same username there.

Regarding the dial - Radio Daze let me down on another radio that I really need to finish. Both dials were gone when I got it. Gone as in terrible shape. I put the pieces of the dials together on my scanner and did a 1:1 scan of the two dials I need. Very high resolution. I sent it to them in an email and they never replied. Nothing.
 
Sounds to me like two problems...

1) the actual humming noise sounds somewhat normal in your video. I'd check and make sure all the foil side of the capacitors were placed correctly I.E foil side to ground or eliminating the noise in the correct direction.

2) maybe you have a spectrum analyzer or a rf generator that is able to sweep the IF. If you replaced the mica caps in the cans or in the IF chain you will probably need to align the IF again. Actually the mica caps were hand picked at the factory of almost all radios so when its been aligned the dial will track properly. That loud nasty noise is a good indicator to me regarding IF alignment.

Just another thought is to check all the coils for broken wires this was very common for they had no protection from lightning back in the day. Any static that came down the Oooo very long outside antenna would destroy the coils.

I have many ham radio receivers in my shop that I will need to rewind coils when I get to them that is lol.

Just my thoughts we all have them lol

Great thread... looking forward to the progress :)

Dave

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(1) All of my caps have the foil side marked (I marked them) and I replaced them one for one so I couldn't screw it up. "One of these days" I'm going to build Paul Carlson's foil side tester but in the meantime I used an audio sig gen and signal tracer to id the foil side. The only thing I didn't test were resistors. It's a battery radio so "normally" power is pure DC.

(2) I didn't get into the IF cans or touch any mica caps. The tuning section of this radio (farm radio from the late 40's) is made up of iron cores the move up and down through coils not the usual rotating plate variable cap.

I have an SA but not a good RF sig gen. here. It's at home. My work bench at home (there's a vice for gun repair under the rags in the left):

p2689759705-4.jpg

This is the little AC power supply that I made (HV and filament supply). The board was milled on my Othermill (it has a new name now but that's what it was called when I bought it):

p3745269518-5.jpg


Osh Park version of the same board:

p3697263463-4.jpg


Recapped radio

p3605131903-4.jpg
 
One of these days" I'm going to build Paul Carlson's foil side tester

Yeah I'm in the same boat lol ..

Dave :)

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I looked up Paul Carlson on his hum testing capacitors. Instead of a scope, one can use an audio amp. If the hum is weak, foil side. Reverse the cap, the hum will be loud. In the late 1970s I worked on Kimball organs. You could trace the problem by touching different places on the circuit boards with your finger and listen for the hum. No hum, that is where the problem most likely be. Before I forget to mention these instruments were low voltage solid state. I'm sure that this technique would work on tube organs, but it might get a bit exciting:einstein:.
 
Cobrage401 said:
Nice!! I have also completed a Atwater Kent model 20 sometime ago. Its sitting in my living room with the matching speaker horn.

Wonder if we have enough people interested in this we may start a group?

I'm working on my lathe and mill so a bit slow on radios at the moment however machinist or like me tinkering machines lol I have learned go hand and hand with restoration of old radios at times.

Dave

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Click to expand...
Before I worked on the Atwater-Kent 20c, I built a cradle to hold the chassis when it was out of the case. Made it a lot easier to work on. Tuning was a piece of cake, You take your antenna touch the capacitor of the grid of the detector, then tune that dial. Do the same on 2nd rf, Then finally on the first rf. Just don't forget to write the dial numbers down. Sorry I don't have a picture of the cradle. Maybe after this virus thing is over, I can run over and see my friend get a picture.
 
Just wondering if you had any progress on your radio?

Dave

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