TB 9-6625-1966-24
(5) Adjust calibrator from 0 to 500 mV and observe that function generator
frequency output starts and stops oscillations on oscilloscope between 0 and 500 mV.
(6) Set TI + INPUT PHASE switch to - (negative) and reverse cable on calibrator
for negative output.
(7) Repeat (5) above.
b. Adjustments. No adjustments can be made.
21. Phase Lock
a. Performance Check
(1) Connect equipment as shown in figure 3.
(2) Position controls as listed in (a) through (e) below:
(a) MODE switch to PHASE LOCK.
(b) FREQUENCY switch to >50 kHz.
(c) + INPUT PHASE - switch to + (positive).
(d) CAL UNCAL switch to B.
(e) START/STOP PHASE control to center.
(4) Adjust calibrator frequency to 100 Hz and output for 3.535 V rms.
(5) Set oscilloscope vertical MODE switch to ALTERNATE and horizontal
TIME/DIV switch for 4 or 5 cycles of display.
(6) Obtain phase lock by slowly rotating TI PHASE control. If the two displays on
oscilloscope are not in phase, and if TI LOCK RANGE pointer is not centered, perform
b (1) below.
NOTE
To quicken phase lock, set TI MODE switch to FREE RUN
until meter pointer indicates left of lock range; then set MODE
switch to PHASE LOCK for lock-in conditions.
(7) Adjust both function generator and calibrator frequencies for 1 kHz and function
generator FREQUENCY dial to 10.
(8) Repeat (6) above. If meter pointer is not centered and displays on oscilloscope
are not in phase, perform b (2) below.
b. Adjustments
(1) Repeat a (3) and (4) above and adjust R5 (fig. 5) until meter pointer is centered
and the two displays on oscilloscope are in phase (R).
(2) Repeat a (7) above and adjust R6 (fig. 5) for indication in b (1) above (R).