TB 9-4920-454-35
CHECK CABLE
RPM INPUT INSTRUMENT CABLE
TEST INSTRUMENT
FREQUENCY COUNTER
CALIBRATOR
TO PIN A
TO PIN B
OUTPUT
RED
HI
LO
BH277 *
BLUE
AIRCRAFT T.C.
LEADS
THERMOMETER
-
RED
BH123-3 *
(SWITCH BOX)
+
BLUE
BH450 *
JETCAL
* SUPPLIED WITH TEST INSTRUMENT
(7) Adjust AMB TEMP (oF) control to 59. If % RPM indicator does not indicate
between 99.5 and 100.5, repeat a (3) through (6) above.
(8) Adjust calibrator output to 0.473 mV dc plus millivolt value equivalent to
ambient temperature obtained in table 3.
(9) If TEMP oC indicator does not indicate between 0 and 4, perform b (5) below.
(10) Reverse leads at calibrator output (fig. 7) (BLUE to HI and RED to LO).
(11) Adjust calibrator output to 33.329 mV dc less millivolt value equivalent to
ambient temperature obtained in table 3.
(12) If TEMP oC indicator does not indicate between 796 and 804, perform b (6)
below.
(13) Adjust calibrator output to 16.398 mV dc, less millivolt value equivalent to
ambient temperature obtained in table 3.
(14) Adjust oscillator for 1.0 V, 63 Hz (15.873 ms) output.
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