Vertex Standard VX-4000L, Service Manual, Page: 23 / 80

5-2
VX-4000 VHF Low-band Service Manual
50-Ohm
Dummy Load
Inline Wattmeter
Deviation Meter
Frequency
Counter
RF Sampling
Coupler
RF Signal
Generator
Transceiver
Power Supply
13.8V DC
CT-71 connection
Cable
PC
COM port
Alignment
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.
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.
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.
Alignment Channel Frequencies
VHF TYPE A
Channel
Frequency CTCSS DCS
(simplex) Encode Encode
CH1 29.71 MHz None None
CH2 33.35 MHz None None
CH3 36.99 MHz None None
CH4 33.35 MHz 151.4 Hz None
CH5 33.35 MHz None 023
VHF TYPE B
Channel
Frequency CTCSS DCS
(simplex) Encode Encode
CH1 37.01 MHz None None
CH2 43.50 MHz None None
CH3 49.99 MHz None None
CH4 43.50 MHz 151.4 Hz None
CH5 43.50 MHz None 023