M A I N T E N A N C E P R A C T I C E S
NOTE
The residual voltage is the voltage present across motor
when the phase control potentiometer is centered as
accurately as possible. This voltage is very small. Some¬
where in the order of 0. 5to 2. 5millivolts depending upon
the particular unit under test.
KEY ITEMS
DE TAI L S TE P S / WO R K I T EM S
VTVM should indicate 2. 5vdc minimum.
(e)
Adjust the phase control potentiometer for 2mv
(above residual voltage), and observe vtvm across
motor.
VTVM should indicate 5vdc minimum.
(f)
Adjust the phase control potentiometer for 10 mv
(above residual voltage), and observe VTVM
a c r o s s m o t o r .
(2) Indicator Rotation Speed
Pointer should take not more than 9
seconds to rotate 360 degrees.
(a) Adjust phase control potentiometer for 10 mv
(above residual voltage) and observe the time
it takes for the indicator pointer to rotate
360 degrees.
(3) Swi tchi ng Volta ge Tes t
Voltage should indicate aminimum of
7. 5v rms at each point.
(a) Measure the os cillator switching voltage from
pin 6to ground and pin 9to ground, with an
average reading instrument, calibrated rms.
I. RECEIVER OPERATIONAL TESTS
(
(1 ) Tun in g Di al C al ib ra ti on
KEY ITEMS
DE TA I L S T E P S / W OR K I T E MS
(a)
Connect the equipment as indicated in Figure
102.
(b)
S e t t h e r e c e i v e r f u n c t i o n s e l e c t o r s w i t c h t o
REC position.
(c)
S e t t h e b a n d s e l e c t o r s w i t c h t o t h e 1 9 0 - 4 4 0
position.
Signal generator output frequency
should be accurate within 0.01%
frequency tolerance.
(d)
Adjust signal generator to 200 kc, unmodulated.
(e) Adjust receiver tuning dial to 200 kc.
The indicated frequency on the tuning
dial shoqld be within I'l of the signal
generator output frequency.
(f) Adjust the tuning dial control for maximum
indication on the tuning meter and compare
the frequency indicated on the tuning dial
with that of the generator output frequency.
Repeat steps (d), (e) and (f) at frequencies
o f 4 0 0 k c , 5 0 0 k c . 8 5 0 k c . 1 0 0 0 k c a n d
1600 kc positioning the band selector switch
accordingly.
(g)
APRIL 1965
Page 112
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