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RECEIVER
point where the BUSY lamp just turns on.
(1) RF Amplifier
a) Connect the calibrated signal generator to
the antenna connector and set the channel
selector to 147.0 MHz.
b) Tune the signal generator to the receive fre-
quency and peak L101 through
L104
and
TC1 01 through TC104 for maximum S
meter reading.
(2) First IF Amplifier
a) Connect a sweep generator to the second
gate of
Q102.
Connect a oscilloscope
through a detector to the drain of Q103.
b) Set the frequency of the sweep generator
to 10.7 MHz and apply its output. Adjust
T101 until the scope pattern illustrated in
Fig. 9. is available.
Figure
9
c) Disconnect the sweep generator and scope.
Measure the RF injection voltage to the
second gate of Q103. A nominal value is
0.8-1.0 volt rms.
(3) S Meter Sensitivity
a) Apply the signal generator output to the
antenna connector. Peak T102 for
maximum S meter reading.
b) Set the output level of the signal generator
to 20 dB and adjust VRioi for full scale
indication on the S meter.
(4) Squelch Threshold
a) Receive a 0 dB signal from the signal
generator.
b) Set the SQL control on the front panel
fully clockwise. Now adjust VR102 to the
point where the squelch just opens.
c) Set the generator level to —10 dB. Press the
TONE SQ button, and adjust VIZi
03
to the
d) Turn off the signal generator, and turn off
the tone squelch. Check to see that the
front panel SQL control causes the squelch
to open when the knob is turned approxi-
mately to the 9 to 10 o'clock position.
PLL Circuit
a)
Set the channel frequency to 146.00 MHz.
b-) Connect the YC500S frequency counter to
TP1 of the PLL unit and adjust TC309 for
5.1200 MHz, and make sure the RF voltage of
the emitter of
Q312
is approximately 1.6
volts rms.
c)
Connect RF probe of the VTVM to the base
of
Q311
and peak TC308 for maximum
VTVM reading. Slowly rotate TC308 in the
direction of increasing capacitance until the
VTVM reading becomes 5% lower than peak
indication (approx. 60 mV rms).
d)
Connect RF probe of the VTVM to the base
of
Q305 .
Key the transmitter and peak
T3o2
for maximum VTVM reading (approx.
170 mV rms).
e)
Connect the YC-5 00S frequency counter
between the cathode of
D302
in PLL unit and
ground. Set the FUNCTION switch to SIMP.
Adjust TC30 2 for 135. 3 MHz counter reading.
f)
Set the FUNCTION switch to —600. Key the
transmitter and adjust TC303 for 134.7 MHz
counter reading. Then Adjust TC304 for
135.900 MHz at +600.
g)
Set the FUNCTION switch to SIMP. Press
5 UP switch down. Adjust TC305 for 135.305
MHz in receive mode. Key the transmitter at
—600 and adjust TC306 for 134.705 MHz; at
+600 kHz adjust TC307 for 135.905 MHz.
h)
Connect VTVM (DC 10 V range) between the
cathode of
D324
and ground. Adjust TC3o
for 3.4 volt VTVM reading.
i)
Connect RF probe of VTVM between TX out
terminal and ground in PLL unit. Peak T403
- T408
for maximum VTVM reading in trans-
mit.
- 22 -
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