AN/URM-43

Overview

A portable general purpose radio frequency absorption type wattmeter used to measure output power and to facilitate tuning of transmitters. It may be used as a dummy load of 51.5 ohms up to 60 watts, as a modulation monitor, as an accurate radio frequency resistance, and for loss measurements on transmission lines. Power indications are read directly on a double scale dc microammeter in rf watts.

Technical Description

Circuit Information

The circuit consists of a 50-ohm coaxial load resistor and a dual range crystal rectifier type voltmeter capacitively coupled to the load resistor. The dummy load-voltmeter housing is oil filled and surrounded by a finned radiator structure. A neoprene expansion -diaphragm, which prevents pressure rise with temperature, is mounted on the front of the housing.

Power Supply

None

Frequency Range

Wattmeter, 30 to 600 mc. Dummy load, 0 to above 900 mc. Power Range: 2 to 60 w in two ranges, 0 to 15 and 0 to 60 w

Type of Reception

CW, AM, FM, or TV type signals

Voltage Standing Wave Ratio

Less than 1:1

Output Impedance

51.5 ohms

Accuracy

±2% of full scale reading

Temperature Range

-40° C (-40° F) to +55° C (+131° F)

Major Unit

1 - AN/URM-43A 7" x 5" x 9"; 9 lbs



Tubes, Crystals, Transistors

• 1 - JAN-1N82 (Crystal Rectifier)

Reference Data and Literature

NAVSHIPS 91842 (Instruction Book)

TO 33A1-7-9-11 (Instruction Book)