720-A

The General Radio 720-A Frequency Meter was introduced in Catalog K4 (1945) and remained available through Catalog P (1959).

The Type 720-A is a heterodyne type frequency meter using a calibrated oscillator from 100 to 200 MHz. Using harmonics frequency measurement from 10 MHz to 3 GHz are possible. Using a built in antenna to couple the unknown a zero beat can be obtained and monitored. The beat note is displayed on a panel meter and heard with an internal speaker. The 720-A can be powered by Burgess 6TA60 battery or the Type 1261-A power supply. "Bias Cells" provide grid bias potentials B1 and B2. See "Bias Cell" information below.

Specifications

• Frequency Range: Fundamental frequcncy range is from 100 to 200 MHz. harmonics 10 to 3000 MHz
• Calibration: The main dial is calibrated in frequency, each division corresponding to 1 MHz
• Accuracy: The overall accuracy of measurement is 0.1 %

Links

• Experimenter describing Type 720-A July 1945
• Bias Cell Data
• 1N21B Microwave Diode Data

Photos

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  1261-A Power Supply Installed

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