[TA Forbes]

Got an interesting 1920s set yesterday.

Nameplate says IVEYLINE//Manufactured By// The Southern Toy Company// Hickory, NC

The tube lineup from left to right is: UX199, X171A, MU20, MU20, CX300
The X171 is a Gold Seal tube, and the UX199 is in an adapter which in turn is mounted in the socket.

Unfamiliar with the MU-20 tube. One of them has on it's base Davin Amplifier//Type MU-20// Fil Volts 6// Fil Amps 1/4

   
   
   
   

[Keith]

Neat looking set. that MU-20 tube is an odd one never heard of it before either.

Have you tried to power the set yet?

[TA Forbes]

Still trying to figure it out. I don't think the tube complement is right, the UX199 and x171 seem out of place before the Daven three tube amplifier.

I am thinking that 01As should go there. But I am not real spun up on these older 20s sets, so I want to figure everything out before I plunge madly ahead.

[Ron Ramirez]

Very neat acquisition, Tom!

I do think, however, that someone just stuck some tubes in the front end of your radio - it should not have a UX-199 and a 71A, but two 01A tubes. The 199 requires a lower filament voltage than the 01A.

I've heard of the Daven tubes. Somewhat rare, I believe. If your set has an entire Daven three tube amp, that alone may well be a real "find." In that case, the radio should probably use a 201A RF amp, 201A or 200A detector, then the three stage audio amp.

[TA Forbes]

Yes, that is what I am thinking! The UX199 is in an adapter, too, and I have never heard of an X171 being used as a detector.

BTW the X171 is a gold seal tube, also relatively rare. Where the MU6 tube should go in the output portion of the Daven amp is a CX300 tube.

Maybe I can trade someone the gold seal X171 for a MU-6...??

[Arran]

I have heard of UX171As being used as power output tubes in 1920s battery sets, usually installed after the fact, but not as a detector. The 199 is wrong, with or without an adapter, and there isn't much advantage to using one that I can think of since they have a 3 volt filament I think. MU-6 sounds like an old military tube designation, but then again there was no rhyme or reason to how a company labeled their tubes in those days.
Regards
Arran

[TA Forbes]

A fellow on ARF sent me the following link:

http://books.google.com/books?id=zd8DAA ... or&f=false

In the 1928 article there is information about using the 171 tube as a detector.

Additionally, he noted the presence of a rheostat with the UX199 and stated that it was common to use the 199 as an RF tube in sets like this one due to their low inter-electrode capacitance. The rheostat would drop the V for the 199's filaments.

Very interesting...!!