12-14-2013, 08:20 PM
Allow me to address the feedback tap issue...
Another collector came up with a way to get around the feedback tap problem. It involves connecting a 1/2 watt resistor to the high side of the output transformer secondary; the other end of this resistor connects into the volume/tone control circuit as the original tap did. You will have to experiment with different values for this resistor to find the "sweet spot" for your set; it will vary, depending upon the individual radio, between 22 and 100 ohms. Some work well with 68 ohms; others need less; still others, more.
Philco actually used the resistor for inverse feedback in some of their postwar console models; this is where my friend got the idea.
Another collector came up with a way to get around the feedback tap problem. It involves connecting a 1/2 watt resistor to the high side of the output transformer secondary; the other end of this resistor connects into the volume/tone control circuit as the original tap did. You will have to experiment with different values for this resistor to find the "sweet spot" for your set; it will vary, depending upon the individual radio, between 22 and 100 ohms. Some work well with 68 ohms; others need less; still others, more.
Philco actually used the resistor for inverse feedback in some of their postwar console models; this is where my friend got the idea.
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Ron Ramirez
Ferdinand IN
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