[volt-nuts] PPM LTD Model 410/411 Voltage Reference

Rob Klein rob.klein at smalldesign.nl
Sun Sep 1 16:36:40 EDT 2013

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.


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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