General Electric model 12C107

This is a 1951 model, one of the last years for 12-inch round screen sets. I found it in an estate sale while driving home from church one Sunday, and bought it, some home TV service books and inexpensive test equipment all for under $20. The previous owner, a tinkerer all his life, had died and his children were cleaning out the house. Inside the set I found a receipt from a TV service shop in my town, dating from the later '50s, and evidence of some crude repairs to the high voltage section. The set is very clean inside and out, and I've tested the tubes (mostly good), but haven't begun replacing parts yet.

This is a 20-tube "AC/DC" hot-chassis set, with series filaments and voltage doubler selenium rectifier high voltage supply. It's an intercarrier design, with 44 MHz IFs and a 1N64 germanium diode video detector. A 1N65 does duty as a DC restorer (video clamp). The tuner has two RF amplifiers: the first is a triode-connected 6AU6 with broadly-tuned input; the second is a 6BC5 with AGC applied.

That long gold-tone trim piece between the screen and the front panel controls hides a cut-out for a UHF tuner. GE anticipated the arrival of UHF channels well before it actually happened in mid-1952.