View source for 720-A

{{GR Product
|model=720-A
|codes=FANCY
|class=frequency standards and meters
|summary=Frequency Meter
|image=GR 720-A Close-up.jpg
|caption=General Radio 720-A Frequency Meter
|series=
|introduced=1945
|discontinued=1959
|designers=Eduard Karplus
|manuals=
* [[Media:720-A Frequency Meter.pdf|General Radio 720-A Manual]]
{{Catalog History}}
}}
The '''General Radio 720-A Frequency Meter''' was introduced in {{Catalog K4}} and remained available through {{Catalog P}}. 

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.