04-14-2013, 08:55 AM
Looking at the tube data sheet, the normal plate current is about 41 mA, so your transformer needs to have at least this primary current rating. This is confirmed from the schematic where it shows the cathode voltage at 5.6V. Using Ohms law, this gives a total cathode current of 5.6/120 ohms, or about 46 Ma, which includes a few mA of screen grid current.
The schematic shows a transformer secondary impedance of 3.4 ohms, so your replacement transformer should have a 3 to 4 ohm spec. So what you are looking for is a transformer with a 2500 ohm primary and a 3-4 ohm secondary with a 40+ mA current rating. The actual DC resistances are not really significant if these specs are met.
The schematic shows a transformer secondary impedance of 3.4 ohms, so your replacement transformer should have a 3 to 4 ohm spec. So what you are looking for is a transformer with a 2500 ohm primary and a 3-4 ohm secondary with a 40+ mA current rating. The actual DC resistances are not really significant if these specs are met.
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