SB 200 with 200 watts out ???

Discussion in '"Boat Anchor" & Classic Equipment' started by ka7gtp, Jul 1, 2008.

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  1. W8JI

    W8JI Ham Member QRZ Page

    In general you can have a bad 572 and still have nearly full output. this is because the drive power that used to go to two tubes shifts to one tube, so you drive the snot out of the one tube that is good.

    The exception to this is if a wire is broken to the anode of one tube. Then the good, but disconnected, tube gets almost half the drive power. If the emission in one tube is gone, output is not reduced that much (unless the good tube is damaged).

    It sounds to me like you have several things wrong. This is a good lesson.....don't do multiple changes unless everything is working and you only change one or two things at a time. :)

    Anyway, you probably will have to work your way back through everything. Someplace something is mis-wired and it is stopping the metering. As for the low output, it could be from multiple things. Could be the grid resistors opened up, could be input SWR, could be tubes. Without a working meter to read grid current and plate current it is tough to know what is wrong. So fix the meter first!!
    73 Tom
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