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Thread: Randall RD45 oscillating

  1. #1
    Senior Member
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    Randall RD45 oscillating

    Hi, I got an oscillating Randall RD45 on the bench. Clean channel is ok, when activating Boost in Gain channel, V2 is oscillating in higher gain settings. Swapping tubes ( V1, V2) did not help. Unfortunately I could not get a schematic, Randall refuses to hand out any schematics.
    I'll try to fix it with a snubber cap (100pF) across V2's plate resistor(s), but maybe there's some better cure?
    Thanks for help and informations,
    Zouto

  2. #2
    Senior Member mozwell's Avatar
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    Not sure how close this is, but attached is the sch for the RD50
    Attached Files Attached Files

  3. #3
    Senior Member
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    Aug 2007
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    Thanks a lot, there are some differences in design, fixed bias in RD45 vs. cathode bias in RD50 etc., but it helps. Double sided pcbs are are drag to trace. I'm still trying to get the right schematics.
    Zouto

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