Sangamo Weston high-frequency milliampere meters, England. Portable precision electrical measuring instruments calibrated in milliamperes H.F. (high frequency), designed for testing radio transmitters, radar equipment, and other high-frequency circuits. Each meter is housed in a robust metal portable case with carrying handle and calibration certificate panel. Instruments of this type were commonly used in telecommunications laboratories and military electronics servicing. Mid-20th century, c.1940s–1960s.
