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".
A look at the analogue circuits from the top.
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
I also have.
Reading the production codes on the chips, it must have been built in 1974.
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.
I bought this meter in november 2006.
The seller did not have documentation but he did have a measurement cable
When I tried the meter, it started making gentle noises, coming from the
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!