E.F. Johnson Company 242-20X1-213, Manual

Page: 99 / 198

7-1
August 2000
Part No. 001-2001-200
ALIGNMENT AND TEST PROCEDURES
SECTION 7 ALIGNMENT AND TEST PROCEDURES
7.1 RECEIVER ALIGNMENT
C
R I T I C A L A D J U S T M E N T
The TCXO must be adjusted within 5 minutes of turn-
ing the AC power on to the repeater. Do not under
any circumstances try to set frequency later on in any
of the tests, as TCXO frequency stability cannot then
be guaranteed.
Refer to Figure 7-1 for component locations.
Refer to Figure 7-6 for equipment needed and setup
diagram. Select "RECEIVER" from the "TEST"
menu in the Repeater Software.
7.1.1 PRETEST
Preset L102, L103, L104, L108, L109, L110,
L140 and L141 tuning screws about 1/4 inch above
the top of the casting.
For 12.5 kHz operation, place jumper plugs
P203, P204 and P205 across pins 2-3 of J203, J204
and J205.
For 25 kHz operation, place jumper plugs P203,
P204 and P205 across pins 1-2 of J203, J204 and
J205.
7.1.2 VOLTAGE MEASUREMENTS
Apply power to the Receiver by plugging the 20-
pin cable from the RF Interface Board into J201 (see
Figure 7-1
).
Measure the voltages at the following pins.
U301, pin 3 +6V DC
±
0.3V
U302, pin 3 +12V DC
±
0.4V
U303, pin 3 +12V DC
±
0.4V
U304, pin 3 +12V DC ±0.4V
R402/R403 junction +3.5V DC
±
0.1V
7.1.3 PROGRAM TUNE-UP CHANNEL
For Receivers operating between:
132-150 MHz, 150-178 MHz.
1. Using the PC and software, program the Synthe-
sizer for the Receive frequency.
2. Tune the VCO capacitor L102 for +7V DC
±
0.05V
at TP401.
Increase the receive frequency by 1 MHz.
The voltage on TP401 shall be less than 15V.
Decrease the receive frequency by 1 MHz.
The voltage on TP401 shall be greater than 2.5V.
3. Alternately tune CV151 and CV152 in 1/2-turn to
1-turn increments until a voltage is measured at
TP401. At that time, tune CV151 for a peak, then
CV152 for a peak.
4. Retune CV151/CV152 for a peak at TP401.
For Receivers operating within 2 MHz of the top of the
receive band (148-150 or 176-178 MHz).
1. Program the Synthesizer for the Highest receive fre-
quency (i.e. 150 or 178 MHz).
2. Set the control line voltage for 15V at TP401.
Check 2 MHz below the programmed frequency
(i.e. 148 or 176 MHz) to verify that the control volt-
age at TP401 is greater than 2V. The repeater
receiver can now be programmed for the desired
operating frequency.
For Receivers operating within 2 MHz of the bottom of
the receive band (132-134 or 150-152 MHz).
1. Program the Synthesizer for the Lowest receive fre-
quency (i.e. 132 or 150 MHz).
2. Set the control line voltage for 2V at TP401.
Check 2 MHz above the programmed frequency
(i.e. 134 or 176 MHz) to verify that the control volt-
age at TP401 is less than 15V. The repeater receiver
can now be programmed for the desired operating
frequency.
NOTE: The Channel Frequency and Synthesizer Fre-
quency appear at the bottom of the screen.