10-13-2022, 04:46 PM
Good Sleuthing RetroRev. As a kid, one of the many dumb things I did on purpose was to attempt to fix Heathkit projects that never worked when someone else built them. Sometimes, another set of eyes will solve the problem. Unfortunately, for this radio, you are the other eyes! Give yourself a pat on the back when you get this going.
BTW, if you are using a PM speaker and did not "up" the capacitance of the filters, you may get a low hum, even with the volume control down. This is because in a speaker employing a field coil, there is a "hum bucking coil" in series with the speaker voice coil. This is engineered to cancel power supply hum by being wound in "reverse polarity" (maybe not the best description but should work) to the direction of the field coil. In addition, the field coil acts as a "choke", giving resistance to the "Pulsating DC" ripple in the power supply that a plain ol' dropping resistor does not provide.
BTW, if you are using a PM speaker and did not "up" the capacitance of the filters, you may get a low hum, even with the volume control down. This is because in a speaker employing a field coil, there is a "hum bucking coil" in series with the speaker voice coil. This is engineered to cancel power supply hum by being wound in "reverse polarity" (maybe not the best description but should work) to the direction of the field coil. In addition, the field coil acts as a "choke", giving resistance to the "Pulsating DC" ripple in the power supply that a plain ol' dropping resistor does not provide.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis
Best Regards,
MrFixr55
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