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Frequency Meter FR-4/U

Frequency Meter FR-4/U; MILITARY U.S. (ID = 2338933) Equipment Frequency Meter FR-4/U; MILITARY U.S. (ID = 2338934) Equipment
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Frequency Meter FR-4/U; MILITARY U.S. (ID = 2338933) Equipment
MILITARY U.S.: Frequency Meter FR-4/U [Equipment] ID = 2338933 1253x987
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For model Frequency Meter FR-4/U, MILITARY U.S. (different makers for same model):
Front view of the frequency meter S/N 0204, yr. 1957
Country:  United States of America (USA)
Manufacturer / Brand:  MILITARY U.S. (different makers for same model)
Year: 1954 ? Category: Service- or Lab Equipment
Valves / Tubes 30: 6AU6 6AH6 12AT7 5654 5725 5670 5751 2BP1 0A2 5Y3WGTA 6Y6G
Wave bands Wave Bands given in the notes.
Power type and voltage Alternating Current supply (AC) / 115/230 Volt
Loudspeaker - - No sound reproduction output.
Power out
from Model: Frequency Meter FR-4/U - MILITARY U.S. different makers
Material Metal case
Shape Boatanchor (heavy military or commercial set >20 kg).

One of the latest and most accurate analog frequency meter, designed to measure frequencies in the range from 100 kHz to 20 MHz over seven bands. 0.001 percent accuracy, calibrated against an internal thermostated crystal reference.

Depending upon the frequency the set operates as heterodyne direct or indirect frequency meter. in the first case the unknown frequency beats with one harmonic of the 10 kHz internal reference. The mixer output in the 15 to 20 kHz band is the compared on the CRT display against the frequency of an internal 15 to 20 kHz interpolation oscillator. In the indirect mode, the unknown frequency beats with the frequency, or its harmonics, generated by a proxy oscillator, continuously compared against the harmonics of the internal reference on the CRT display.

Quite remarkable the analog division chain used to generate the 10 kHz reference starting from the thermostated 1250 kHz crystal quartz. It uses three divide-by five stages, each one based upon a closed loop containing a mixer feed by the input signal from one side, a tank circuit tuned at one fifth of the input frequency at its output and a multiplier by four feeding the other side of the mixer.

Net weight (2.2 lb = 1 kg) 86 lb 0 oz (86 lb) / 39.044 kg
Literature/Schematics (1) -- Original-techn. papers. (TM 11-5094)

Model page created by Emilio Ciardiello. See "Data change" for further contributors.

All listed radios etc. from MILITARY U.S. (different makers for same model)
Here you find 352 models, 304 with images and 168 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.