Philips PM2443 DC DVM (1974)
The PM2443 is a 4,5 digit precision DC voltmeter.
It is made in Japan.
This specimen is working fine
The PM2443 is a precision digital voltmeter.
It has a 4,5 digit display using B-5853 nixie tubes.
It uses TTL (Transistor-transistor logic) for the digital circuitry.
The case can be placed on a shelf, or tilted on the workbench using the
handle on the case as a tilt stand.
The range is set electronically, using a number of reed switches.
Ranging can be set to "automatic" or "manual".
The PM2443 is made in Japan, as can be read on the front.
The circuit boards bear a "TR" logo, so I presume it has been
built in the Takeda Riken factories, like the
PM2423 I also have.
Reading the production codes on the chips, it must have been built in 1974.
I bought this meter in november 2006.
The seller did not have documentation but he did have a measurement cable
with it.
When I tried the meter, it started making gentle noises, coming from the
reed relays.
It worked just fine.
A few months later, I got a copy from a fellow nixie enthousiast.
So now I was able to appreciate the delicate and service-friendly design
of the device. A venerable achievement, Philips-San!
A look at the analogue circuits from the top.
In order to prevent noise and ground loops that would interfere with the precision of the measurements, Philips has taken a number of measures: there is a separate "guard" receptacle for the shield of the input cable, the case has a number of internal shielding plates, the analogue and digital power are completely separated and the connection between the analogue and digital parts is using small toroid pulse transformers for isolation.
A look at the digital circuits from the bottom.
Copyright © 2007 by Onno's E-page published 2007-04-07