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#1
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How much of the new PS are you planning to use? Are you planning to replace the 80 with a 5Y3 or run both some how?
What I would do is use only the transformer from the parts set. Mark all leads (ie. line, 6.3V heater, 5V rect heater, rect plate winding and it's center tap) before harvesting the parts trans. To start, disconnect the original rect plate winding (including center tap) on the radiola (tape over the ends so they don't short). Connect the rect plate winding from the new parts trans to the plates of the 80, and the center tap of the new trans to chassis output pin 7 (ie. where the old center tap used to connect), then connect the line input of the new trans to a variac. Meter the High dc output of the PS chassis, and if feasible the AC plate voltage on the rect tube. Report back the variac setting that gives designed DC rail voltages.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
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#2
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Hi Tim,
Before you get carried away. The tested voltages you show would seem to be correct. Tubes like the 71's normally never were operated above 180 volts and voltage drop through plate reactor seems correct at 135 volts. The second picture you posted shows/ states that tube #7, a 227 has a plate voltage of 160. That's what you found. I think your troubles are elsewhere in the radio. You could have shorts in the trimmer caps, opens in the coils, etc. Have you tried signal injection starting from the 71 output back to the 1st RF amp. Ed |
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