Thanks Gary,
Next month (2 weeks) I need to get a half dozen tubes. Should the
12AX7A's be matched? I only need one.
Garey Barrell wrote:
Richard -
The ZERO adjust should not affect the PLATE meter, only the S-Meter.
There is some _mechanical_ interaction between the two movements,
but in transmit the plate meter should read cathode current of the
Final only, and the S-Meter should indicate ALC action. In receive,
the S-Meter should indicate signal strength and the PLATE meter will
_slightly_ react to movement of the S-Meter.
So the "correct" setting of the ZERO pot is as described below and in
the manual. The only adjustment for the PLATE meter is by selecting
R13, which was selected at final test. The only reason to change it
is if R45 has changed value with age or overload, or has been
replaced. It's best to calibrate the meter to read 0.1A correctly,
since that is critical to proper operation of the Final stage, and the
meter is NOT a high quality item and is somewhat inaccurate over it's
entire range.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Richard Palmer wrote:
Gary,
Since I cleaned it I knew where it was. I noticed that the zero
adjust affected the meter's reading of the bias also ... so I wanted
to get it set correctly.
Thanks for your help,
Richard Palmer
Garey Barrell wrote:
Richard -
The S-Meter is Zero'd with the cleverly disguised ZERO control on
the right side of the chassis.!! :-)
Disconnect antenna, detune RF TUNE control, and adjust ZERO control
for S1 on the meter. There is no S0 on Drake meters!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Richard Palmer wrote:
There is on thing that is not spelled out. Zeroing the meter. I
cleaned all the pots and when I went to zero the meter I found
nothing to help me determine the proper setting. So any help there
is appreciated.
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