I am working on a 20’s homebrew radio that has a pair of Songbird Master-Tone Audio Interstage Transformers in it. One is a 3.5:1 and the other a 5:1.
These transformers are so pretty that I thought I would post a picture of one of them.

The band is chromed steel and the end bells are stamped aluminum.

The transformer shown had some odd resistance readings when I checked it out so I opened it up. I found that it must have had an open primary and that someone had removed the wire from the primary and installed R/C coupling. This is the first 20’s audio that I have opened and found separate bobbins for the primary and secondary coils.

I rewound the primary with 4100 turns of #40 wire and reassembled it. Ohm readings are ok but I will have to complete work on the rest of the chassis before the smoke test.
Ed.