720-A: Difference between revisions

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


* [[Media:GR Exp 720-A 07_1945.pdf|Experimenter describing Type 720-A July 1945]]
* [[Media:GR Exp 720-A 07_1945.pdf|Experimenter July 1945 describing Type 720-A]]
* [[Media:Grid Bias Cells.jpg|Bias Cell Data]]
* [[Media:Grid Bias Cells.jpg|Bias Cell Data]]
* [[Media:1N Series Microwave Diode Data Sheet.pdf|1N21B Microwave Diode Data]]
* [[Media:1N Series Microwave Diode Data Sheet.pdf|1N21B Microwave Diode Data]]
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GR 720-A Top A.jpg
GR 720-A Top A.jpg
GR 720-A Top.jpg
GR 720-A Top.jpg
GR 720-A Schematic Inside A.jpg
</gallery>
</gallery>


[[Category:Frequency Standards and Meters]]
[[Category:Frequency Standards and Meters]]

Latest revision as of 19:28, 30 May 2024

General Radio 720-A
Frequency Meter
General Radio 720-A Frequency Meter

Available from 1945 to 1959

Manuals
Catalog History
 Document Year Page
Catalog K4 1945 144
Catalog L 1948 180
Catalog M 1951 212
Catalog N 1954 220
Catalog O 1956 85
Catalog P 1959 87
(All manuals in PDF format unless noted otherwise)

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

Photos