Hi Tony,
While I know nothing about this particular device, green precision
wire-wound resistors in an English instrument almost
certainly are made by Mann Components (later taken over to become
Vishay-Mann). They're easily recognized by
an "MC" monogram.
Regards,
Rob.
Op 29-8-2013 3:01, Tony Greene schreef:
Greetings. I have lurked awhile and have finally found a reason to register
and post.
I recently purchased a PPM Ltd. (England) model 410/411 voltage reference.
This unit is green colored and takes up one rack unit. It appears to be zener
based, it has a black box on the PCB that I beleive houses/sheilds the zener.
On the rear panel it has bananna jack that is labeled 6.25498V. It has a 1KV
and 100V input divider to 1 volt output. It also has a switched output of 10V,
1V, 100mv, 10mv, 8mv, 6mv, 4mv, 2mv, 1mv, and zero volts. The unit uses
binding post for the inputs and outputs and it also has a sense and guard
binding post.
The unit operates on 120 or 240 VAC and had 14 ea "C" nicad cells which were all
corroded. The batteries were configured so that 2 cells provided a negative supply, and 12 cells
provided a positive supply. The unit uses 0.005 percent wirewound resistors, they are green in
color, but I do not reckonize who made the resistors. The unit uses OP07 op amps, using the round
"TO" style cans of old opamps. The unit has a calibration sticker showing it was
calibrated on 9-87, a transformer inside shows a made date of 1979.
I have not been able to locate any information on the net about the unit. I
would appreciate any information any person may have on the unit.
Thanks, Tony
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