08-22-2024, 09:59 PM
If the speaker was meant for a portable radio with a 1J6 Dual Triode output tube in Class B operation, the output transformer for the speaker has a 10K Ohm Plate to plate impedance. The output of the 1J6 is 2.1 W but runs at 135V as opposed to the 42 that puts out 2 W into a 7K Ohm impedance with 250V on the plate. You could use the speaker with the 1J6 transformer, but it would be a mismatch with reduced output. You also have to deal with the fact that there is no voice coil to act as a choke for the power supply. Speakers for most transformer powered AC sets have a field coil impedance of about 1,150 Ohms, except for older Philco sets like the Model 20. If a suitable electrodynamic speaker or a choke can't be found, substitute a resistor for the field coil. Start with a 1,150 Ohm resistor. However, consider upping capacitor 11A to about 30uF to compensate for the lack of inductive filtering. If this causes too high a B+ voltage, increase the resistance of the resistor that was substituted for the speaker field coil.
IMHO, leave the speaker for the battery operated radio, as these radios are historically significant, and get a modern replacement, and find a correct transformer. A transformer for a single ended 47, 2A5, 41, 42, 6F6 or 6K6 should work.
IMHO, leave the speaker for the battery operated radio, as these radios are historically significant, and get a modern replacement, and find a correct transformer. A transformer for a single ended 47, 2A5, 41, 42, 6F6 or 6K6 should work.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55