Ericsson LBI-31511B, Maintenance Manual, Page: 10 / 18

TEST CABLE TRANSMITTER ALIGNMENT
19C850590G1
(19C850593, Rev. 4)
SYNTHESIZER AND TRANSMITTER ALIGNMENT
TEST EQUIPMENT REQUIRED
1. Watt meter, 50 ohm (capable of measuring 150 watts & 1 watt)
2. Digital Voltmeter
3. RF Frequency Counter
4. RF Voltmeter
5. Power Supply, 13.8 Vdc regulated
6. GE Test Set, 4EX3A11 with Test Set Adapter 19C850590G1
7. Tuning Tool 19B800716P2
PRELIMINARY CHECKS AND ADJUSTMENTS
Connect black plug of GE Test Set to RF Metering jack J101. Connect red system metering plug to J602, system metering.
Set polarity to "+" and voltage range to the 1 volt position (Test 1).
ALIGNMENT PROCEDURE
Synthesizer TX and RX Vco
The TX and TX VCO voltage adjustments are described by the following steps 1-5. After the lock detect light D713 goes
out (step 1 and 3) each VCO is adjusted after selecting the appropriate channel for the maximum reading indicated.
If the light is not out, all readings are meaningless.
As long as the highest operating frequency (VCO voltage) does not exceed the maximum meter reading and the lowest
operating frequency (VCO voltage) is not less than the minimum meter reading, the adjustment is proper.
When the two frequency spread is minimal it is acceptable to center tune the VCO voltage between the maximum and
minimum meter readings.
If the highest operating frequency is at the low end of the frequency split (example 451.025 MHz on the 450-470 MHz split),
the VCO reading may never reach the maximum. Therefore adjust the lowest operating frequency to a VCO voltage above the
minimum reading.
NOTE
Refer to Figure 5 for location of tuning adjustment controls.
NOTE
Before aligning or making any adjustments to the transmitter, be sure that the output of the 9 volt regulator is set for
9.0
±
0.05 Vdc. Monitor J602-3 with a digital voltmeter and adjust R703.
LBI-31511 LBI-31511
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