RECEIVER SENSITIVITY TEST. - TM-11-5820-401-34-30368

TM 11-5820-401-34-3/0967-LP-432-3060

5-2. VOLUME CONTROL TEST. (CONT)

STANDARD. Tone from speaker should be clear with no scratchiness or sudden changes in volume

at any point in the rotation of the VOLUME control.

4. If volume changes suddenly, if tone is scratchy, or if no tone at all is heard, see trouble-

5-3. RECEIVER SENSITIVITY TEST.

PURPOSE. This test checks the ability of the R-442/VRC to detect low-level rf signals by measuring

its SIN AD at several frequencies. SINAD gives receiver sensitivity in terms of the following ratio:

Signal + noise + distortion/noise + distortion.

SIN AD is expressed in decibels. The better a receiver's SINAD, the better signals, even weak ones,

can be heard over unwanted internal noise. The SINAD for the R-442/VRC should be at least -10 db

(from a zero-db reference) when the rf level is 0.5 v.

TEST EQUIPMENT AND MATERIALS

Power Supply PP-1104(*)/G

Matching Unit CN.901/U

Resistor, 600.ohm 5%, 2-watt

Distortion Analyzer TS-723(*)/U

Frequency Counter AN/USM-207

Rf Cables (two) RG-58/U

Test Cable No. 1

Signal Generator AN/URM-103

Adapter (T-Connector) UG-274 B/U

NOTE

The 600-ohm resistor provides an impedance matching load for the audio transformer.

The resistor is used in place of Loudspeaker LS-454/J, which would issue a loud,

distracting tone when the R-442/VRC VOLUME control is adjusted during the test. If no

600-ohm resistor is available, however, the loudspeaker must be connected.

5-4