Service manual

ALIGNMENT AND TEST PROCEDURES
7-12
Month 2000
Part No. 001-2004-601
7.4 FULL REPEATER ALIGNMENT
7.4.1 PERFORMANCE TEST PROGRAM
1. Select the TEST - FULL REPEATER - ALL TEST
and press Enter.
7.4.2 REPEATER SETUP
The VIKING VX repeater has been pretested at
the factory, therefore only performance tests are
required to check the repeater. Refer to test setup dia
-
grams for equipment and cabling diagram.
Turn on the repeater power supply switch (S508)
in the IAC or engage the locking lever (see Figure
7-25).
The baud rate for communications between the
Universal Station and the PC Programmer is user con
-
figurable using J3 on the MPC. The factory default is
9600 baud.
The operating code has been programmed at the
factory. The parameters are programmed into the
MPC. If these parameters have changed or are incor
-
rect, exit this test and reprogram the repeater.
It may be necessary to remove the RF assembly
from the chassis and connect via extension cables for
some of the tests or adjustments.
NOTE: All audio generators and audio voltmeters are
unbalanced unless specifically stated otherwise. All
references to J2 refer to the green connector on the
back of the repeater.
7.4.3 TRANSMITTER TEST/ADJUSTMENTS
Transmit Mode
1. Use the "Turn on carrier" button to key the repeater.
2. The Transmit LED on the IAC should turn on to
indicate the repeater is transmitting (see Figure
7-25).
3. Use the "Turn on carrier" button to unkey the
repeater.
Transmit TCXO Frequency Adjustment
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.
1. Use the "Turn on carrier" button to key the repeater.
2. Check the frequency of the transmitted signal. The
frequency should be ±50 Hz of the channel fre
-
quency.
3. Adjust the frequency with Y401 (TCXO) on the
Exciter (see Section
7.2.5).
4. Use the "Turn on carrier" button to unkey the
repeater.
Transmitter Output Power Adjustment
1. Use the "Turn on carrier" button to key the repeater.
2. Check the transmit output power. The power can be
adjusted from the computer using the Power Con
-
trol Indicator. The test equipment should be cali-
brated for ±2W.
3. Use the "Turn on carrier" button to unkey the
repeater.
4. Use a jumper wire to ground pin 7 (PTT_N) to
pin 21 (GND) on J2 on the back of the cabinet
(see Figure 7-12). The transmitter should key up
and achieve rated power.
5. Remove the wire. The transmitter should unkey.
7.4.4 RECEIVER TESTS/ADJUSTMENT
NOTE: Jumper J103 selects between a 12.5 kHz IF
and a 25 kHz IF.
NOTE: If this is a voting repeater, it is not equipped
with a receiver.