Speaker help for a newbie.

[Phil]

Welcome to the forum!
Since you are missing the speaker I am operating on the assumption you are also missing the output transformer, which appears to have been part of the speaker assembly. You will need a transformer of about 10K plate to plate primary with a secondary to match the speaker you chose, probably 8 ohms. You can probably find something suitable on eBay or from Hammond. You will also need a choke to replace L1. It is probably not critical value wise, since, if I am reading the schematic correctly, this set utilizes a 400 mFd capacitor input filter (!?). I think this is probably an error since it would exceed the 80 rectifier tubes rating by a huge amount. 4 mfd would be more typical. I would look for something on the order of 20-40 henrys @ 30-50 ma. Someone else may have better information for you on this. If it were me I would put a 10K adjustable wire wound in series with the choke and adjust it for 220 volts on the plate of the 6C5.

[Electronic M]

Originally Posted by Phil

Welcome to the forum!
Since you are missing the speaker I am operating on the assumption you are also missing the output transformer, which appears to have been part of the speaker assembly. You will need a transformer of about 10K plate to plate primary with a secondary to match the speaker you chose, probably 8 ohms. You can probably find something suitable on eBay or from Hammond. You will also need a choke to replace L1. It is probably not critical value wise, since, if I am reading the schematic correctly, this set utilizes a 400 mFd capacitor input filter (!?). I think this is probably an error since it would exceed the 80 rectifier tubes rating by a huge amount. 4 mfd would be more typical. I would look for something on the order of 20-40 henrys @ 30-50 ma. Someone else may have better information for you on this. If it were me I would put a 10K adjustable wire wound in series with the choke and adjust it for 220 volts on the plate of the 6C5.

It looks like the audio output transformer is powered through the field coil... I'd probably look for a choke rated for 150mA or more. Don't want to smoke the choke with excessive current.

[old_coot88]

Originally Posted by Electronic M

... I'd probably look for a choke rated for 150mA or more. Don't want to smoke the choke with excessive current.

Actually, just to get the radio running and verify operation, he could temporarily sub a wirewound resistor of appropriate value (and wattage rating) for the choke.

[Electronic M]

Originally Posted by old_coot88

Actually, just to get the radio running and verify operation, he could temporarily sub a wirewound resistor of appropriate value (and wattage rating) for the choke.

Absolutely. I've seen power resistors even used as a permanent fix before. Heck he could probably jump the thing out if he's running it on a variac (so he can control the B+ to keep it from being excessive) and the only consequence would be increased hum while it was set up that way.

I just don't like advising someone to buy a part that might smoke in the application.

[old_coot88]

Increasing the filter caps' value a bit above original specs might just subdue hum acceptably (using the power resistor fix).