724-A: Difference between revisions

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Type '''724-A Precision Wavemeter'''.
{{GR Product
|model=724-A
|codes=WOMAN
|class=frequency standards and meters
|summary=Precision Wavemeter
|image=GR 724-A Close-Up.jpg
|caption=General Radio 724-B Precision Wavemeter
|series=724
|introduced=1936
|discontinued=1945
|designers=
|manuals=
* [[Media:GR 724-A Precision Wavementer Data Cards SN1397 08_14_45.pdf|General Radio 724-A Precision Wavemeter Data Cards SN1397 1945]]
{{Catalog History}}
}}
The {{Title|General Radio 724-A Precision Wavemeter}} was introduced in {{Catalog J}} and remained available through {{Catalog K4}}.
 
The Type 724-A is an absorption-type wavemeter with a range from 17 kHz to 50 MHz using seven coils with an accuracy of ±0.25%. The primary application of the 724-A is oscillator and transmitter frequency measurement.
 
The capacitor used is similar to the [[722-N|Type 722-N Precision Capacitor]]. It is connected to the inductor through a [[774|Type 774 coaxial connector]].
Resonance is achieved using one of three methods – absorption, reaction, or beat method. 
Using the panel galvanometer, the absorption method is employed.
Regardless of the method, once resonance is achieved, it is a matter of using the correct chart for the coil in use to determine the frequency.
 
Type 724-A was supplied as a collection of calibrated components sharing the same serial number, i.e. the capacitor, inductors, and calibration charts must have the same serial number to achieve the stated accuracy.
 
The 724-A replaced the [[224-A|224-A Wavemeter]] with improved coils and a galvanometer replacing the thermocouple type indicator.
The wavemeter was furnished with a wooden storage case, fitted with lock and carrying handle.
This case has compartments for holding the capacitor, inductors, and calibration charts.
The 724-A uses a 1G4GT/G triode vacuum tube, resulting in the need for a 1.5 V battery for the heater.
 
Note: The instrument shown in the photos below uses a 1LE3 loctal battery triode. It appears to be a production change.


==Specifications==
==Specifications==
* '''Frequency Range:''' 16 kHz to 50 MHz using seven inductors
* '''Accuracy:''' ±0.25% between 50 kHz and 50 MHz, 1% between 16 and 50 kHz
* '''Inductors:''' 7 coils wound on isolantite forms and enclosed in molded bakelite cases
* '''Capacitor:''' Precision worm-drive type similar to Type 722
* '''Resonance Indicator:''' galvanometer and vacuum tube rectifier combination


==Links==
==Links==


* [[Media:GR Exp 724-A 03_1936.pdf|Experimenter March 1936 describing Type 724-A]]


==Photos==
==Photos==
<gallery>
<gallery>
GR 724-A Front.jpg
GR 724-A Meter w_Coil.jpg
GR 724-A Case.jpg
GR 724-A Case Open.jpg
GR 724-A Case Contents A.jpg
GR 724-A Contents.jpg
GR 724-A Coils A.jpg
GR 724-A Coils B.jpg
GR 724-A Right.jpg
GR 724-A Top.jpg
GR 724-A Meter Case Bottom.jpg
GR 724-A Meter Case Empty.jpg
GR 724-A Inside Left.jpg
GR 724-A Inside Rear.jpg
GR 724-A Inside Right.jpg
GR 724-A Inside Top.jpg
GR 724-A Inside Bottom.jpg
GR 724-A Case Frequency Meter.jpg
GR 724-A Card A SN1397.jpg
GR 724-ACard B SN1397.jpg
GR 724-ACard C SN1397.jpg
</gallery>
</gallery>


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

Latest revision as of 18:17, 30 May 2024

General Radio 724-A
Precision Wavemeter
General Radio 724-B Precision Wavemeter

Available from 1936 to 1945

Manuals
Catalog History
 Document Year Page
Catalog J 1936 57
Catalog K1 1939 161
Catalog K2 1942 176
Catalog K3 1944 147
Catalog K4 1945 149
(All manuals in PDF format unless noted otherwise)

The General Radio 724-A Precision Wavemeter was introduced in Catalog J (1936) and remained available through Catalog K4 (1945).

The Type 724-A is an absorption-type wavemeter with a range from 17 kHz to 50 MHz using seven coils with an accuracy of ±0.25%. The primary application of the 724-A is oscillator and transmitter frequency measurement.

The capacitor used is similar to the Type 722-N Precision Capacitor. It is connected to the inductor through a Type 774 coaxial connector. Resonance is achieved using one of three methods – absorption, reaction, or beat method. Using the panel galvanometer, the absorption method is employed. Regardless of the method, once resonance is achieved, it is a matter of using the correct chart for the coil in use to determine the frequency.

Type 724-A was supplied as a collection of calibrated components sharing the same serial number, i.e. the capacitor, inductors, and calibration charts must have the same serial number to achieve the stated accuracy.

The 724-A replaced the 224-A Wavemeter with improved coils and a galvanometer replacing the thermocouple type indicator. The wavemeter was furnished with a wooden storage case, fitted with lock and carrying handle. This case has compartments for holding the capacitor, inductors, and calibration charts. The 724-A uses a 1G4GT/G triode vacuum tube, resulting in the need for a 1.5 V battery for the heater.

Note: The instrument shown in the photos below uses a 1LE3 loctal battery triode. It appears to be a production change.

Specifications

  • Frequency Range: 16 kHz to 50 MHz using seven inductors
  • Accuracy: ±0.25% between 50 kHz and 50 MHz, 1% between 16 and 50 kHz
  • Inductors: 7 coils wound on isolantite forms and enclosed in molded bakelite cases
  • Capacitor: Precision worm-drive type similar to Type 722
  • Resonance Indicator: galvanometer and vacuum tube rectifier combination

Links

Photos