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Garble audio from the Philco model 20 radio - corrected.
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12-18-2006, 12:04 AM
Hi,

I previously posted a problem (audio garbled when it received strong signal) of the radio. The problem was found and corrected. I still did not know the reason yet.

The problem was from a shifted bias of the audio driver tube type 27A. The bias was provided through a 500K Ohm resistor. The resistor was replaced with a 25K Ohm resistor and the problem was corrected.

Another symptom was that the voltage divider (resistor 25 and VR 1) was off from the spec. It also affected the volume control in which I alway needed to turn to the vincinity of max volume to hear the signal.

The radio now works reasonably. If you have any clue about the reason why the radio worked after the resistor was changed from 500K to 25 K, please let me know.

Thanks and 73,

Jonathan, AB6LS.
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  1. The PHILCO Phorum
  2. Philco Radio Discussions
  3. Philco Electronic Restoration