Avo Test Bridge.

[Shaman]

Avo Test Bridge, this fine piece of equipment tests capacitors, resistors, leakage of capacitors, power factor, measures against external standards, and last but not least its a valve volt meter, quite impressive for 1938....regards....Alan.

[attachment=1486] [attachment=1487]

[AlanBeckett]

Alan,
There are at least two different meter scales for these - see attached - but I haven't figured out why.
I've got the Manual and Circuit etc if you want it.
Alan

[attachment=1489][attachment=1490]

[OldTickTock]

Mine has the second dial and dates from 1946

[AlanBeckett]

Chris,
Interesting. I have a suspicion that the first scale is the 'real one' and the second is during and shortly after the war when things were tight. It just looks a bit crude, so perhaps they had trouble getting the right ones.
Alan

[Shaman]

Thanks Alan, for the Avo test bridge, schematics very much appreciated...kind regards....Alan.

[fido]

One of my first tasks I was taught as a lab technician in a metallurgy lab when I was 16 was to use a thermocouple bridge to calibrate optical pyrometers on salt bath furnaces. This was done first thing every morning using an old wooden cased instrument and a metal sheathed thermocouple that was dipped into the molten salt. The salt was at 1280 degrees C for heat treating high speed steel and the metal sheaths for the T/Cs had quite a short life.