I've got a Philips PT 2248 Electronic Reference Unit from around the 70s. Nothing to find on the internet about that one. Maybe anyone has old material from Philips? The device and its specs could be mentioned in a catalogue or that good old quarterly magazine which Dave mentions in eevblab 94.
At full scale the device is about 3% out. On the inside it contains a shielded box in which I can spot a Zener Diode in an old quartz-like metal package. And there are two trimmers.
I would guess one is for zero and the other for the gradient. But I would prefer not to screw around blindly and screw it up. Because 3% out is better than completely warped.
I have two of these.
On one of them are the specs.
Got one just now. Need to carefully try to start it up as its 220V.
Anyone knows what it was for ?
Interresting bit of kit.