931B RMS Differential Voltmeter

The 931B is a true RMS differential voltmeter that uses a thermal element as part of the AC to DC conversion process.

It operates over the frequency range 2 Hz to 2 MHz and can measure up to 1 kV RMS.

There is a "recorder output" on the rear panel that provides a DC voltage proportional to the meter offset, thus enabling small changes in the input voltage to be examined.