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General Radio 1650-B
Impedance bridge
General Radio 1650-B Impedance Bridge

Available from 1968 to 1978+

Catalog History
 Document Year Page
Catalog T 1968 74
Catalog U 1970 76
Catalog73 1973 154
Catalog78 1978 17
(All manuals in PDF format unless noted otherwise)

The General Radio 1650-B Impedance Bridge was introduced in Catalog T (1968) and remained available through Catalog 1978.

The Type 1650-B is the improved version of the iconic 1650-A with specifications similar to its predecessor. Improvements include an added conductance bridge, slow motion dials for DQ and RCL, battery check setting on the function switch, and a side panel for connections preciously on the front panel. The battery compartment was redesigned, with the batteries contained in a removeable tube that is accessible after removing the bridge from its case.

The 1650-B also features the "Orthonull" device that helps prevent a sliding null (see 1650-A).


  • Capacitance: 1 pF to 1100 μF in 7 ranges
  • Inductance: 1 μH to 1100 H in 7 ranges
  • Resistance: 1 mΩ to 1.1 MΩ in 7 ranges
  • Conductance: AC or DC, 1 nS to 1.1 S in 7 ranges
  • D: (series capacitance) 0.001 to 1 at 1 kHz, (parallel capacitance) 0.1 to 50 at 1 kHz
  • Q: (series inductance) 0.02 to 10 at 1 kHz, (parallel inductance) 1 to 1000 at 1 kHz
  • Basic accuracy: ±1% of full scale, ±5% for dissipation factor
  • Internal oscillator: 1 kHz ±2%
  • Frequency range: 20 Hz to 20 kHz (to 100 kHz with reduced accuracy)