Hello Bob.
I hope the snow is melting in an orderly fashion out your way these days.
Here are a couple of photos comparing the 19-Set Voltmeter on the left with the 52-Set Voltmeter on the right. Both are designed to mount in a 2-3/16 inch panel hole with 12, 4 and 8 o’clock mounting hardware positions, but the similarity pretty much ends there.
That panel hole arrangement was quite possibly standard on many wireless sets, but the meters for the most part would be custom designed to work with the circuits unique to each set.
It would also seem that wireless meters evolved quite a bit from simple indicators to quite useful diagnostic tools for the operator. These dual scale meters not only allow the operator to monitor input voltage to the supply on the smaller scale ( 6, 12 or 24 volts), the Low Tension side of things, but also the power supply output voltage on the larger scale, the High Tension part of the set.
The Low Tension would typically be the battery input voltage, which was also the filament voltage for the tubes. A drop in Low Tension voltage would warn the operator it was time to switch to the second set of wireless batteries and recharge the first set. Normal Low Tension readings with no output from the wireless would indicate a possible failure in one or more valves.
The meter on the 19-Set could also tell you when the set was properly tuned to the available aerial you were using and the relative strength of your out going signal.
The 52-Set meter could do all of that plus had a feature on the receiver meter switch that allowed the operator to test each individual valve in the receiver to see if it was in good working order. The Operator could also turn this switch to a ‘SENDER’ position and then use a similar switch on the Sender (Transmitter) to test the valves in that unit as well.
All that while brewing up his morning tea!
David
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