Vacuum Tube Voltmeter 400C

Voltage Range:
12 ranges, selected on front panel switch. Full scale readings of:
0.001 V, 0.1V, 10V
0.003 V,  0.3 V,  30.0 V
0.01 V,  1.00 V,  100 V
0.03 V.  3.00  V, 300 V

Frequency Range: 20 cps to 2 mc.

Accuracy:
The over-all accuracy of the meter is within ±3%  below 100 kc and ±5% from 100 kc to 2 mc. Line voltage variations from 105 to 125 volts or changing tubes will affect the reading by less than  3% at all frequencies
below 100 kc.

Calibration:
Calibrated to read rms value of sine wave. Voltage indication proportional to average value of full sine wave. Linear voltage scale with db calibration from -12% +2 dbm. 10 db intervals between voltage ranges.

Input Impedance: 10 megohms shunted by 15 µµf on
ranges 1.0 V to 300 V; 24 µµf on ranges 0.001 V  to 0.3 V.

Output Circuit: Maximum output 0.5 V corresponding to full scale deflection of meter. Internal impedance 1,000 ohms. Gain 500 when instrument is on the 0.001 volt range.