Frequency meter BC-221-AK

Signal Corps
Description

The Frequency Meter BC-221-AK is a precision instrument designed to measure or radiate radio frequency impulses between 125 and 20,000 kHz. It is portable and completely self-contained instrument used mainly to calibrate field radio receivers and transmitters by direct comparison with the calibrated variable frequency oscillator of the frequency meter. The control panel itself is covered when not in use by a hinged lid that contains the units Calibration Book. 
 

History

Since it is completely portable and self-contained, iy was a workhorse for adjusting aircraft radio transmitters and radio receivers and transmitter on the field during wwII.
 

Technological Innovations

Each meter contains a 1,000 kc crystal oscillator circuit with is used both as a source of accurate radio frequency signals at multiples of 1,000 kHz and for calibrating the variable frequency oscillator of the instrument at a number of points. These points of frequency calibration are called "Crystal Check Points". Each BC-221 was individually calibrated and the calibration book marked with the serial number of the unit.

Applications

Adjusting aircraft radio transmitters and radio receivers and transmitter on the field.
 

Manufacturer
Signal Corps
Country of Origin
USA
Inventory Number
004
Incorporation to Collection
05/13/2015
Type
Test Equipment
Rights
TechRocket RM
Application
On the field frequency tuning of US Army transmitters during wwII