• Country
• United States of America (USA)

• Manufacturer / Brand
• General Radio Company; Cambridge (MA)

• Year
• 1975 ?

• Category
• Service- or Lab Equipment

• Radiomuseum.org ID
• 257672

• • alternative name: GenRad

Click on the schematic thumbnail to request the schematic as a free document.

• Number of Transistors
• Semiconductors present.

• Semiconductors

• Wave bands
• - without

• Power type and voltage
• Alternating Current supply (AC) / 90-127;180-253 at 48-440Hz Volt

• Loudspeaker
• - - No sound reproduction output.

• Material
• Metal case

• from Radiomuseum.org
• Model: Digital Impedance Meter 1685 - General Radio Company;

• Shape
• Tablemodel, low profile (big size).

• Dimensions (WHD)
• 432 x 142 x 413 mm / 17 x 5.6 x 16.3 inch

• Notes

• The 1685 Digital Impedance Meter is an all solid-state instrument that automatically measures series capacitance and inductance at two frequencies, 120Hz and 1 kHz, and measures resistance at DC. These measurements can be made on command or repetitively, with measurement time variable between 0.25 s and 10 s , with results furnished by means of a digital readout display.

  The basic accuracy is 0.1% +2 counts for DC and 1 kHz measurements and 0.5% + 1 count for 120 Hz measurements. For DC and 1 kHz measurements, the full-scale digital readout indication is 19999; for 120 Hz operation it is 1999.

  The decimal points and units are also displayed; the units are displayed on the RANGE switch dial. The range is manually set.

  The meter measures capacitance from .01 pF (one digit) to 20,000 µF, inductance from .01 µH to 2,000 H and resistance from 0.1 mΩ to 20 MΩ.

  For ac measurements, the dissipation factor, D, or quality factor, Q, is also indicated. The value of D or Q is obtained by a manual dial adjustment. However, if this dial is set to the desired D or Q limit, there is an automatic indication if their value is exceeded. An optional limit Comparator (High/Low) can be added to the instrument.

• Net weight (2.2 lb = 1 kg)
• 10.2 kg / 22 lb 7.5 oz (22.467 lb)

• Mentioned in
• - - Manufacturers Literature

• Author
• Model page created by Antonio Marra. See "Data change" for further contributors.

• Other Models

• Here you find 238 models, 212 with images and 128 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from General Radio Company; Cambridge (MA)