05-18-2023, 10:52 PM
Chas, great info on the hf bypass cap. Jordan, I agree with Chas, that if you think that the speaker impedance is really that low, shoot between 7 and 10K for the transformer primary, more toward the 10K.
One other thing. If the radio was operated with an open output transformer primary, the 6F6 may be trashed. With the primary open, the screen takes all the current, and it was not designed to do so. The screen will glow bright yellow to almost white hot and eventually short to the suppressor or to the control grid, both being really BAD (burning out the cathode resistor, the field coil, the power supply, etc.). I saw this on a Philco 89 with a nice Globe 42. Fortunately, I caught it in time.
One other thing. If the radio was operated with an open output transformer primary, the 6F6 may be trashed. With the primary open, the screen takes all the current, and it was not designed to do so. The screen will glow bright yellow to almost white hot and eventually short to the suppressor or to the control grid, both being really BAD (burning out the cathode resistor, the field coil, the power supply, etc.). I saw this on a Philco 89 with a nice Globe 42. Fortunately, I caught it in time.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
