RECEIVER SENSITIVITY TEST. - TM-11-5820-401-34-30090

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

3-2.

VOLUME CONTROL TEST. (CONT)

NOTE

To produce a display on the AN/USM-207, the AN/U RM-103 rf level must be increased

by turning the LO RF UV control clockwise. When the display appears, readjust the

AN/URM-103 RF TUNING control until the AN/USM-207 indicates 30.00 MHz, and reset

the LO RF UV control to 20 .

2. Disconnect T-connector from AN/USM-207.

3. Turn R-442/VRC VOLUME control fully clockwise, then fully counterclockwise.

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 troubleshooting

3-3. 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. SIN AD gives receiver sensitivity in terms of the following ratio:

Signal + noise + distortion/noise + distortion.

SINAD 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 .

TEST EQUIPMENT AND MATERIALS

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

Power Supply PP-1104(*)/G

Matching Unit CN-901/U

Distortion Analyzer TS-723(*)/U

Maintenance Kit MK-1978/VRC

Frequency Counter AN/USM-207

Rf Cables (two) RG-58/U

Signal Generator AN/URM-103

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