Specifications

VCO Tuning
3. Adjust C435 for a DC voltage of 2.75 ± 0.05 volts
at TP402. On base station units, check the maxi-
mum and minimum receive frequencies and insure
that the voltage at TP402 is between 1.6 and 4.4
volts.
4. Connect a frequency counter to the output of
TEST PROBE A. See Figure below. Hold TEST
PROBE A across R456 and adjust the trimmer ca-
pacitor inside Y402 so that the frequency counter
shows a frequency 21.4000 MHz below the receive
frequency to within ± 100 Hz.
IF Adjust
5. Connect an oscilloscope to TP401.
6. Connect an RF signal generator to the ANTENNA
Connector on the rear of the unit (on repeater units,
make sure the REP LED is off and do not connect
to the TX ANTENNA connector). Set the RF sig-
nal generator frequency to that of the unit and set
the RF output level such that a 0.1 volt p-p 455
kHz signal appears on the oscilloscope.
7. Adjust L408 and L407 for maximum signal on the
oscilloscope. If necessary, reduce the RF signal
generator output level to keep the signal on the os-
cilloscope at 0.1 volt p-p.
8. Modulate the RF signal generator with a 1000 Hz
tone modulated at ±3.0 kHz. Set the signal gener-
ator output level to 100 microvolts (-67 dBm). Ad-
just L409 for maximum audio at the speaker
terminals. Readjust L408 and L407 slightly, if
necessary, for lowest distortion on the distortion
analyzer.
Front End Alignment
9. Adjust L401A , B, and C and L404A, B, C, and D
(in that order) for maximum signal on the oscillo-
scope. Repeat once more. On base station units,
check at the maximum and minimum frequencies
and readjust, if necessary for good sensitivity at all
frequencies.
Remote Audio Output Adjustment
10. Increase the signal generator output level to 1mv (-
47 dBm). Connect the audio voltmeter to pin 3 of
P502 on the rear of the unit.
11. Adjust R480 on the Main PC board for the desired
output level.
TRANSMITTER
Preliminary
1. For base station units, set the unit to a transmit fre-
quency nearest the middle of the frequency list.
The IF stages have been aligned at the factory
and should not normally require realignment
when the operating frequency range of the
unit is changed.
NOTE
This adjustment need only be made if the user
wishes to use the remote audio output.
NOTE
The transmitter PTT must be depressed to
make the following adjustments.
NOTE
Maximum frequency spread is ± 5 MHz; ± 3
MHz for best performance.
NOTE
Test Probe A is an RF coaxial cable with a 1000 pF, 50V
min. DC blocking capacitor placed in series with the cen-
ter conductor. Observe proper polarity of the probe when
connecting the unit; one side is connected to test equip-
ment ground.
Figure 6 - Test Probe A
AE/LZB 119 1882 R1B
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