Vertex Standard VX-4000L Service Manual page 23

Alignment
Before beginning, connect the transceiver and PC
using the CT-71 programming cable, and download
the EEPROM data from the transceiver to the com-
puter.
Store this data in a disk file so that it can be saved
and retrieved later. Using the table below, program
the channel, CTCSS, and DCS alignment settings for
your transceiver version. Upload this file to the
transceiver.
Note:Signal levels in dB referred to in this proce-
dure are based on 0 dBµ = 0.5 µV (closed cir-
cuit).
Caution:Do not connect the audio output line to
ground, and be certain that the speaker has
adequate capability to handle the audio
output from the radio.
Because of the bridge audio amplifier cir-
cuit used in the radio, it is necessary to con-
struct and use a simple audio load test
adapter as shown in the schematic diagram
below, when conducting receiver align-
ment steps.
Alignment Channel Frequencies
VHF TYPE A
Frequency
Channel
(simplex)
CH1 29.71 MHz
CH2 33.35 MHz
CH3 36.99 MHz
CH4 33.35 MHz
CH5 33.35 MHz
VHF TYPE B
Frequency
Channel
(simplex)
CH1 37.01 MHz
CH2 43.50 MHz
CH3 49.99 MHz
CH4 43.50 MHz
CH5 43.50 MHz
5-2
CTCSS DCS
Encode Encode
None None
None None
None None
151.4 Hz None
None 023
CTCSS DCS
Encode Encode
None None
None None
None None
151.4 Hz None
None 023
PLL & Transmitter
Set up the test equipment as shown for transmit-
ter alignment.
Maintain the supply voltage at 13.8 V DC for all
steps.
50-Ohm
Dummy Load
Inline Wattmeter
RF Sampling
Deviation Meter
Coupler
CT-71 connection
Cable
Frequency
Counter
PLL VCV
r Connect the positive lead of the DC voltmeter to
test point TP1007 (VCV) on the Main Unit, as in-
dicated in the figure, and connect the negative
lead to chassis ground.
r Set the transceiver to the high band edge fre-
quency channel, then adjust L1021 on the Main
Unit for 7.0 V on the voltmeter.
r Key the transmitter, and adjust L1022 on the
Main Unit for 7.0 V on the voltmeter.
r Next select to the low edge frequency channel
and confirm the VCV is more than 1.8 V (for type
A) or 1.7 V (for type B) on the voltmeter.
r Key the transmitter, and confirm the VCV is more
than 1.8 V (for type A) or 1.7 V (for type B) on the
voltmeter.
PLL Reference Frequency
With the wattmeter, dummy load and frequency
counter connected to the antenna jack, select the
band center frequency channel, and select the "low"
power output level.
Key the transmitter, and adjust TC1001 on the
Main Unit, if necessary, so the counter frequency is
within 100 Hz of the channel center frequency for
the transceiver version.
VX-4000 VHF Low-band Service Manual
RF Signal
Generator
Transceiver
Power Supply
PC
13.8V DC
COM port