E.F. Johnson Company VIKING VX, Manual

Page: 109 / 198

ALIGNMENT AND TEST PROCEDURES
7-11
August 2000
Part No. 001-2001-200
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
7-14
).
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.
7.4.3 TRANSMITTER TEST/ADJUSTMENTS
Transmit Mode
1. Press the space bar to key the repeater.
2. The IAC Transmit LED should turn on to indicate
the repeater is transmitting (see Figure 7-14).
3. Press the space bar 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.
4. Press the space bar to key the repeater.
5. Check the frequency of the transmitted signal. The
frequency should be
±
50 Hz of the channel fre-
quency.
6. Adjust the frequency with Y401 (TCXO) on the
Exciter (see Section 7.2.5).
7. Press the space bar to unkey the repeater.
Transmitter Output Power Adjustment
1. Press the space bar to key the repeater.
2. Check the transmit output power. The power can be
adjusted from the computer using the cursor Up/Dn
and PgUp/PgDn keys. The test equipment should be
calibrated for
±
2W.
3. Press the space bar to unkey the repeater.
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.
Receiver 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. Check the receiver injection frequency by using a
"sniffer" pickup loop, or RF probe connected to a
suitable frequency counter placed near TP102 in the
Receiver (see Section 7.1.4).
2. Adjust Y401 (TCXO) on the Receiver to within
±
50 Hz of the channel fre 52.95 MHz.