1644-A

Resistance Range: 1 kΩ to 1000 TΩ in ten decade ranges.
Accuracy: from 1 kΩ to 10 GΩ ±1% Basic accuracy see manual.
Test Voltages: 10, 20, 50, 100, 200, 500, and 1000 Volts.
Short-Circuit Current: &lt;15 mA at 10 V to 50 V; &lt;10 mA at 100 to 1000 V.

General Radio 1644-A

megohm bridge General Radio 1644-A Megohm Bridge Available from 1965 to (?) Manuals General Radio 1644-A Manual 1644-0100-A 1964 (All manuals in PDF format unless noted otherwise)

The General Radio 1644-A Megohm Bridge is a Megohm Bridge introduced in 1965 Catalog S and remained available through Catalog78. The Type 1644-A is a bridge type instrument used for resistance measurements in 9 ranges from 1 kΩ to 1 TΩ. The bridge is a modified Wheatstone bridge design. It contains a built in vacuum tube detector and high voltage power supply. Besides measuring resistors its uses are semiconductor leakage, capacitor resistance and insulation resistance for example. The Type 1644-A replaces the Type 544-B.