TB 9-6625-2059-24
15. Deviation Meter and Residual FM
a. Performance Check
(1) Position switches as listed in (a) through (e) below:
(a) DEV-VERT V/DIV outer to 6 kHz.
(b) FREQUENCY MHz to all zeros.
(c) GEN/RCVR to RCVR.
(d) HI LVL - X100 - NORM to HI LVL.
(e) DEV-PWR to 2 kHz.
(2) If DEVIATION (kHz) meter does not indicate zero 1 minor division,
perform b (1) through (3) below.
(3) Set GEN/RCVR switch to GEN. If DEVIATION (kHz) meter does not indicate
0 1 minor division, perform b (1) through (3) below.
(4) Set FREQUENCY MHz switch to 125.500.0.
Connect sensor module to
TRANS-RCVR.
(5) Adjust BFO-RF LEVEL control until 0 dBm light illuminates.
(6) Set measuring receiver to 125.5 MHz in manual tune mode.
(7) Configure measuring receiver to measure peak deviation using 300 Hz HI PASS
and 3 kHz LOW PASS filters. Measuring receiver will indicate less than 100 Hz.
(8) Adjust VAR control until DEVIATION (kHz) meter indicates 2 kHz.
If
measuring receiver does not indicate between 1.86 and 2.14 kHz, perform b (4) below.
(9) Set DEV/PWR switch to 6 kHz.
(10) Adjust VAR control until DEVIATION (kHz) meter indicates 6 kHz.
If
measuring receiver does not indicate between 5.58 and 6.42 kHz, perform b (5) below.
(11) Set DEV/PWR switch to 20 kHz and RCVR WIDE-MID-NARROW switch
to MID.
(12) Adjust VAR control until DEVIATION (kHz) meter indicates 20 kHz.
If
measuring receiver does not indicate between 18.6 and 21.4 kHz, perform b (6) below.
b. Adjustments
(1) Adjust A1A13R71 (fig. 5) until DEVIATION (kHz) meter indicates zero.
(2) Set GEN-RCVR switch to GEN and adjust A1A13R81 (fig. 5) until
DEVIATION (kHz) meter indicates zero. Set RCVR-GEN switch to RCVR.
(3) Repeat (1) and (2) above as necessary.
(4) Adjust VAR control until measuring receiver indicates 2 kHz.
Adjust
A1A13R85 (fig. 5) until DEVIATION (kHz) meter indicates 2 kHz.
(5) Adjust VAR control until measuring receiver indicates 6 kHz. Adjust A1A13R83
(fig. 5) until DEVIATION (kHz) meter indicates 6 kHz.