Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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This is usually an indication of a gassy 6EV7. If you're SURE that you
have a good 6EV7, it could be caused by low bias voltage, but this would
normally cause the Final stage idling current to drift upward also.
There are also several high value resistors in the grid circuit of the
6EV7 that may have gone up in value.
If you have a Hi-Z VTVM or DMM you can check the voltage at Pin 7 of the
6EV7. It should typically be -5 to -7VDC in standby, and near 0 in
transmit.
A high ESR cap at C107 can also cause this. Usually accompanied by the
CW sidetone not keying off between character elements.
73, Garey - K4OAH
Atlanta
Drake C-Line Service Manual
<http://www.k4oah.com>
Tim Randa wrote:
Tim Randa <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Hello to all. Just got a set of C twins and am working the bugs out one
at a time. The vox circuit as me stumped, it seems to work for a few
minuets in the cw mode and then it seems to lock on with none of the
adjustment pots making any difference. I haven't tried it in the ssb
mode but I have replaced the switching tube 6EV7 with no help. Anyone
have any ideas where to look ?
Thanks in advance
Tim KØFL
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