The Telegon oscillator generates an 85 vac 800 hz sinusoid reference signal for instrument synchros. Ours was in pretty bad shape. We emptied out a mud-daubber nest, replaced most all capacitors, found a few shorted wires, added new tubes, and updated the 83V rectifier tube with diode equivalent.
Our output transformer was bad, and the Blue Box folks in Binghamton, only have bad ones left. We tried 2 before giving up. After disassembling a junk output transformer, we measured all the turns for the primary and secondary, wire sizes, etc., intending to rewind it. The more we compared the old transformer to a modern Hammond transformer, the better we liked the Hammond. It is 35 watts, so it will likely last forever. Here is a picture of our restored unit. The Hammond transformer is bigger than the original so we had to move C5 over a bit. It works great!
Our primary guide was linktrainer.net’s document titled “Restoring the Telegon Oscillator” by Steve Edwards. It is excellent. Published here with author’s permission.
You may also be interested in another paper by Steve Edwards of linktrainer.net. Published here with author’s permission.