• Country
• United States of America (USA)

• Manufacturer / Brand
• Keithley Instruments Inc.; Cleveland (OH)

• Year
• 1968 ?

• Category
• Service- or Lab Equipment

• Radiomuseum.org ID
• 115311

• Number of Tubes
• 7

• Valves / Tubes
• 7025 6CM8 12AU7 7025 7025 7025 6CM6 0G3

• Power type and voltage
• Alternating Current supply (AC) / 115; 230 Volt

• Loudspeaker
• - - No sound reproduction output.

• Material
• Metal case

• from Radiomuseum.org
• Model: Differential Voltmeter 660A - Keithley Instruments Inc.;

• Shape
• Tablemodel, with any shape - general.

• Dimensions (WHD)
• 437 x 344 x 140 mm / 17.2 x 13.5 x 5.5 inch

• Notes
• The Keithley 660A is a differential voltmeter, which can be used as potentiometer or as VTVM. As potentiometer it can measure from 100 microvolts full scale to 500 volts, with an error lower than 0.02% in the ranges from 100 mV up. As VTVM itreads from 1 mV to 500 V, with a 3% accuracy, and resistances up to 100.000 megahoms. Input resistance depends upon the selected range, being 50 Mohms from 0.1 V full scale, and raises to infinity at the null. The meter includes the 500 VDC precision voltage reference, the Kelvin-Varley divider and the chopper stabilized null detector.

• Source of data
• - - Manufacturers Literature

• Author
• Model page created by Emilio Ciardiello. See "Data change" for further contributors.

• Other Models

• Here you find 38 models, 33 with images and 16 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Keithley Instruments Inc.; Cleveland (OH)