TB 9-4920-359-24
(4) Adjust R119 (fig. 3) for a frequency counter indication of 1000 ms (R).
(5) Adjust R7 (fig. 3) for a frequency counter indication of 3.0 s (R).
Figure 3. Test instrument - front view.
13. Underfrequency Circuit
a. Performance Check
(1) Set dc power supply to OFF and disconnect frequency counter from equipment setup.
(2) Connect Oscilloscope to J5 UFCAL.
(3) Set dc power supply to ON.
(4) Set TRIP TIME START switch to off (down).
Oscilloscope should indicate
between 20 and 30 V P - P.
(5) If Oscilloscope does not indicate between 1145 and 1165 Hz, perform b (1) below.
(6) Set TRIP TIME-START switch to on (up). If Oscilloscope does not indicate
between 1085 and 1105 Hz, perform b (2) below.
(7) Oscilloscope should indicate between 20 and 30 V P - P.
b. Adjustments
