I need some help with this radio. I have the schematic for the Code 121, but this radio is a bit different. The audio output tube is a 50B5, and the speaker does not appear to have a field coil. Also the filter cap is a triple 40uf and not a dual. All I can get from this radio is a hum, which varies in intensity, and also varies the brightness of the pilot light. I was waiting for some smoke but it never did.

This radio has been worked on before, and I suspect there are things not connected properly. Almost all of the capacitors have been replaced, but I don't think they are the proper values. Does anyone have a good picture of the underside of the chassis for this radio? I know it was working several years ago before being tampered with, and I'd like to get it going again.

Also, I'm not very familiar with tubes since they are before my time. I forgot which way the pins are counted on the tube sockets when looking from the bottom of the chassis. I'm too blind to read the numbers if there are any. Is there a picture somewhere on this site that details pin numbering of sockets? I'm pretty sure it goes clockwise from the notch but I want to make sure.

Thanks for any help you can provide.

Tube pins are counted CW from the notch or spacing, looking from the bottom of the chassis.

:Tube pins are counted CW from the notch or spacing, looking from the bottom of the chassis.

Thanks. Looks like there are several things different on this radio from what is on the schematic. Also, someone put a 7B7 in the RF amp where there is supposed to be a 7C7. Will that work as well?

This is a brown bakelite case radio, the one with the "hippo" look. Anyone else have one of these that can do some comparisons? I'm a bit lost working after someone else on this, and the schematic I have is very hard to read in some spots.

If you look up a 7c7 on the TUBE reference section here on this site you'll see that it shows a 7B7 as a substitue.

:If you look up a 7c7 on the TUBE reference section here on this site you'll see that it shows a 7B7 as a substitue.

Thanks, I should have looked over this site better before posting. I was just excited to find a forum for old radios, and posted right away without looking around :-)

Have done some more testing on the radio. I'm getting about 6 volts of ripple on the output of the rectifier, so I think the filter cap is bad. Oddly enough, when I paralleled another 47uf cap across it, it didn't help much. I'm going to take it to work and get out the ESR meter.

Also noticed the 50B5 takes a really long time (about a minute) to warm up to the "good" scale on my tube tester, and it doen't get too far out of the marginal area when it does. Maybe it is too weak for the radio. I do get some static when switching stations, but it is quieter than the 60Hz hum, and pretty distorted. I could faintly make out someone talking.

I have a question about testing the AF output manually. It appears that I could take another signal source and connect it (through a decoupling cap) between B- and the wiper of the volume pot to get sound through the speaker. Is there any harm in doing this?