Wireless Intercom System Service Manual
ALIGNMENT PROCEDURE
Receive Board - 70714000
Equipment Required:
D Signal Generator
D Sensitive RF Voltmeter
D DC Voltmeter
D AF Voltmeter
1.
Connect the signal generator
to
the Receive
Antenna jack. Set the deviation at
± 3 KHz at
1 KHz. Refer to the frequency chart below.
Look at the marking on the Y301 and set the
generator
to
the corresponding ALIGN fre-
quency.
11.
Place the RF voltmeter probe tip inside the top
ofL304.
12.
Adjust VC304 for a peak indication.
13.
Adjust VC305 for a null indication.
14.
Adjust VC306 for a peak indication.
15.
Place the RF voltmeter probe tip on the collec-
tor
ofQ303
and adjust T301, T302, and T303
for a peak indication.
Y30l
Align
CHl
CH2
CH3 CH4
Marking
171R905
170.705 171.905 171.045 170.245
169.505
207R800 206.900
207.800 207.425 206.800 206.000
213R800
212.900 213.800 213.425 212.800
212.000
2.
Adjust VR309 for 0.44 VDC across R312.
3.
Place the RF voltemter probe tip inside the top
of
L307 and adjust VC307 for a peck indica-
tion.
4.
Set the RF voltmeter to its most sensitive scale
without stray pickup.
5.
Place the RF voltmeter probe tip inside the top
of
L301.
6.
Increase the signal generator output level until
the
RF
voltmeter indication just begins
to
rise.
7.
When adjusting, reduce the signal generator
output rather then reducing the RF voltmeter
sensitivity.
8.
Adjust VC301 for a peak indication.
9.
Adjust VC302 for a null indication.
10.
Adjust VC303 for a peak indication.
3-10
16.
In the following alignment, unless othelwise
directed, adjust the signal generator output
level
to
maintain a DC voltage
of
between 1and
1.5 volts.
17.
Set the signal generator
to
the channel 1 fre-
quency.
18.
Adjust T304, T305, and T308 for maximum
DC voltage at pin 5
of
U301.
19.
Set the signal generator output
to
1 mV and
adjust T309 for maximum audio at pin 7 of
U303.
20. Adjust VR302 for 140 mV of audio at pin 7
of
U303.
21. Set the signal generator output
to
1
~
V and
adjust VR301
to
just extinguish the number 1
LED
on
the front panel.
22. Set the signal generator
to
the channel 2 fre-
quency.