Jerry -
On Board 10, (component side facing the front CO compartment shield,)
there are three pads across the top edge of that board. Looking from
the front of the radio, right to left, they are +245V +150V and
-60V.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Jerry Semones wrote:
I am restoring a TR4CW and have it working except for the AGC. I have
swapped out all of the tubes but I still don't have any AGC action.
While the S-meter does indicate signal strength there is no delay in
the movement. I have measured the voltage and resistance on the 12AX7
AGC tube with the following results:
PIN VDC
1 -.1
2 -51
3 -49
4 0
5 0
6 +1.17 (should be -0.16)
7 -51
8 -49
9 6.3 (fil)
Pin 6 which is the plate of the 12AX7 measured 1.2M to ground but
should be 2.2M according to the manual that I downloaded from the
internet. My schematic copy is not too clear given it's all on one
page in the download. It appears that pin 6 goes through 3 resistors
in route to a -60V source but I can't find that source on my
schematic. Can someone telll me where to find the source of the -60V
feeding pin 6 of the 12AX7?
Thanks & 73' to the group
Jerry K4FJK
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