Film-Tech Forum ARCHIVE: Need help identifying zenith console radio

This is topic Need help identifying zenith console radio in forum Film-Yak at Film-Tech Forum ARCHIVE.

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Posted by Josh Jones (Member # 447) on 05-26-2003, 08:45 PM:

I picked this up from a friend in town. It doesnt work, but has magic eye and is missing a speaker. There is a torn off paper label on the underside of the chassis that says "cabt. 6"

any help would be appreciated.

Josh

Posted by Bruce McGee (Member # 131) on 05-26-2003, 09:33 PM:

Josh:

I cant help with the model, but chances are good that the speaker that is missing has an electromagnet coil on it. It probably also had a matching transformer mounted on it. Best of luck. If I find something similar, I'll let you know.

I have a Philco with an almost identical cabinet from 1941.

Posted by Phil Hill (Member # 371) on 05-26-2003, 10:04 PM:

Josh: What a beauty! I hope you restore it to all it's original splendor...inside and out!

Bruce is correct about the speaker if it's not a PM type. A lot of times, the field coil is used as a choke for the plate power supply and has HV on it. Also, as Bruce says, the audio output transformer may be located on the speaker as well...and also has HV on it.

I see the "Wave Magnet" antenna is still there...Kewl! Hopefully you can find a serial number plate on the chassis and that will lead you to the model and the schematic.

Zenith radios are categorized by the number of tubes and by the year of manufacture. A good site for info on them is:

http://www.oldradios.com/reference/zenith.htm

I have restored cool vacuum tube stuff for many years and really enjoy it….old time radios, ham radio transmitters and receivers, juke boxes and pinball machines. Below are some useful links that you may be interested in. They are directories to many restoration and parts sites.

http://www.justradios.com/links.html

http://www.geocities.com/CapeCanaveral/9178/linkrad.htm

>>> Phil

Posted by Josh Jones (Member # 447) on 05-26-2003, 10:17 PM:

I was kindof expecting a field coil type speaker when I saw the four wires for the speaker. I have some power supply chokes around that I can use. The site says that this radio was built around 1940. I do plan to fix/restore it and use in the livng room [Smile]

So it seems its time to send off a load of cash to antique eletronic supply.

Josh

Posted by Phil Hill (Member # 371) on 05-26-2003, 10:26 PM:

A separate choke will work fine, IF the circuit is configured that way. Make sure you look at how the field wires are connected to the chassis. Some may use a low resistance choke configuration and others are used a bleeder resistors and have a high resistance connected across the HV supply.

If there is not a chassis-mounted audio output xmfr, what is the audio output tube number? I can give you the correct plate load impedance for a replacement transformer so you can us a PM spkr.

>>> Phil

Posted by Josh Jones (Member # 447) on 05-26-2003, 11:12 PM:

The output tube is a 6F6G tetrode, I think. it wants about 7K load impedance, is that right? What kind of speaker would sound good as a replacement? The impedance listed in the schematic for the field coils is around 1250 ohms, it is quite hard to read, but here is the link.

Here

Thanks for the help guys.

Josh

Posted by Paul G. Thompson (Member # 655) on 05-26-2003, 11:30 PM:

That radio is a model 8-S-463. It takes a 10-inch electrodynamic speaker. It covers the AM band, and 2 short-wave bands up to 18mhz. It weighs about 70 pounds. It is 41 inches tall, 27 inches wide, and 18 inches deep.

The 6F6 is a power pentode, but it is not interchangable with the 6V6. The pinouts are different. The 6F6 has the same pinout as the 6K6, but the tube characteristics are a little different. The 6K6 should work as a substitute if the 6F6 is shot.

Posted by Aaron Sisemore (Member # 145) on 05-27-2003, 12:25 AM:

quote:
The 6F6 is a power pentode, but it is not interchangable with the 6V6. The pinouts are different.

Actually, the pinouts of the 6F6, 6K6, 6L6 and 6V6 are exactly the same. EIA base 7AC (6V6, 6L6) and base 7S (6F6, 6K6) are identical. You are correct, however in that the 6V6 is a higher-performance tube (and of different construction, being a beam tetrode rather than a true pentode) than either the 6K6 or 6F6, and therefore has different ratings.

Back to Josh's radio: You are correct with the 7Kohm input impedance for the output tranny. Hammond makes a 'universal' single-ended output tranny that should suit you perfectly.

As for the EM speaker field, if you want to go with a choke (ideally) you can, but you can just as easily replace the field coil with a wirewound resistor.

Any full-range speaker that will fit the hole should do the job, unless you are going for an 'authentic' restoration, in which you might be able to locate a real EM speaker and have a 'correct' replacement. [Smile]

Another suggestion would be to get a hold of a good radio servicing book, such as Marcus & Levy's Elements Of Radio Servicing which will greatly assist in your project.

Good Luck!

-Aaron

Posted by Paul G. Thompson (Member # 655) on 05-27-2003, 12:46 AM:

Aaron, I'll stand corrected on the pin configuration. I just looked again after I read your post, and I said, "OOPS!"

Thanks for pointing that out.