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Philco 38-7 Oscillation
tludka
Junior Member
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Posts: 38
Threads: 9
Joined: Jul 2021
City: Franklin State, Province, Country: Wisconsin
#1

2 hours ago
I have let this one sit because of other duties. Now I am back, and I have a couple of questions. I hooked up a Hammond 125BSE audio transformer to a 4-ohm speaker. I receive a crackle and the putt- putt like a bad filter cap. Since the original speaker was not with the radio, I am using a 1200-ohm resistor for the field coil. The voltage checks from the Philco spec are close to the specs except for one of them. The filter caps have been replaced. If I remove the cap lead from the IF 6K7G tube the reading on the plate seems ok and the putt putt stops. When I attach the cap the reading Justs fluctuates and will not stabilize, and putt putt is back. The cap reads a negative 3vdc disconnected from the tube. I have checked all the resistors and replaced the caps. Checked the wiring several times. The 1st I.F. coils ohm out per the schematic but not sure about the mica caps in it. Could this be the problem?
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  1. The PHILCO Phorum
  2. Philco Radio Discussions
  3. Philco Electronic Restoration