Vertex Standard VX-2000U Service Manual
UHF Land Mobile Transceiver
VX-2000U
Service Manual
©2003 VERTEX STANDARD CO., LTD. E095490A
VERTEX STANDARD CO., LTD.
4-8-8 Nakameguro, Meguro-Ku, Tokyo 153-8644, Japan
VERTEX STANDARD
US Headquarters
10900 Walker Street, Cypress, CA 90630, U.S.A.
International Division
8350 N.W. 52nd Terrace, Suite 201, Miami, FL 33166, U.S.A.
YAESU EUROPE B.V.
P.O. Box 75525, 1118 ZN Schiphol, The Netherlands
YAESU UK LTD.
Unit 12, Sun Valley Business Park, Winnall Close
Winchester, Hampshire, SO23 0LB, U.K.
VERTEX STANDARD HK LTD.
Unit 5, 20/F., Seaview Centre, 139-141 Hoi Bun Road,
Kwun Tong, Kowloon, Hong Kong
40 channel version 4 channel version
Introduction
This manual provides technical information necessary for servicing the VX-2000U UHF Land Mobile transceiver.
The VX-2000U is carefully designed to allow the knowledgeable operator to make nearly all adjustments required for
various station conditions, modes and operator preferences simply from the controls on the panels, without opening the
case of the transceiver. The VX-2000U Operating Manual describes these adjustments, plus certain internal settings.
Servicing this equipment requires expertise in handling surface mount chip components. Attempts by non-qualified
persons to service this equipment may result in permanent damage not covered by warranty.
For the major circuit boards, each side of the board is identified by the type of the majority of components installed on
that side.
In most cases one side has only chip components, and the other has either a mixture of both chip and lead components
(trimmers, coils, electrolytic capacitors, packaged ICs, etc.), or lead components only.
While we believe the technical information in this manual is correct, Vertex Standard assumes no liability for damage
that may occur as a result of typographical or other errors that may be present. Your cooperation in pointing out any
inconsistencies in the technical information would be appreciated. Vertex Standard reserves the right to make changes in
this transceiver and the alignment procedures, in the interest of technological improvement, without notification of the
owners.
Contents
Operating Manual Reprint............................ 2
Specifications................................................... 7
Exploded View & Miscellaneous Parts....... 8
Block Diagram.................................................9
Interconnection Diagram............................. 13
Circuit Description ...................................... 15
Alignment....................................................... 19
Board Unit (
MAIN Unit............................................................... 23
DISPLAY-1 Unit ......................................................55
DISPLAY-2 Unit ......................................................59
VR Unit..................................................................... 63
MIC Unit .................................................................. 64
Schematics, Layouts & Parts
)
1
Operating Manual Reprint
CONTROLS & CONNECTORS
40 channel version4 channel version
Microphone Jack
À
Connect the microphone plug to this jack.
MONI Button & Indicator
Á
This button selects the “squelch” (receiver mute) mode.
When the yellow indicator is off, “tone” or “coded” squelch
is active. When the indicator glows steadily, only “noise
squelch” is active, and any signal present on the channel
will be heard. When the indicator is blinking, the squelch is
disabled, and background noise will be heard if no signal is
present.
A Button & Indicator
Â
This button is provided for an ACCESSORY function such as
HIGH/LOW POWER selection, “TALK-AROUND”, or “CALL
ALERT” functions. The green “A” indicator will be illumi-
nated when this function is active.
VOLUME and POWER ON/OFF Knob
Ã
This knob adjusts the receiver volume, and turns the radio
off when turned all the way to the left into the click-stop.
TX/BUSY Indicator Lamp
Ä
This lamp blinks red when the channel is busy, and glows
steadily red during transmission. Do not transmit when this
indicator is blinking, as a courtesy to other users of the channel.
The following item is unique to the 4-channel
radio versions:
CHANNEL Numbered Indicators & Button
Å
Press the CHANNEL button to select the operating channel; the channel number currently in use will light up on the
display panel.
The following items are unique to the 40-channel
radio versions:
CHANNEL Selector Buttons (p) and (q)
Æ
Push one of these keys to select the operating channel, as
shown on the display.
Numeric Channel Display
Ç
This display area shows the channel number and prioritychannel/scan status.
SEL/PRI Button
È
This button is used to select a channel for “Priority” monitoring, and is used together with the SCAN button to select
the desired scanning mode.
SCAN Button
É
This button is used to activate scanning, to select or remove
channels on the scanning list, and (together with the SEL/
PRI button) to select scanning mode.
P Indicator
11
This small dot indicates Priority Channel status (described
later).
E Indicator
12
This small dot indicates Scanning on/off status (described
later).
2
REAR (Heatsink)
13.6V DC Cable Pigtail w/Connector
À
The supplied DC power cable must be affixed to this 2-pin
connector.
Antenna Socket
Á
The 50-ohm coaxial feedline to the antenna must be connected here, using a “UHF” type (PL-259) plug.
Operating Manual Reprint
External Speaker Jack
Â
An external loudspeaker may be connected to this 2-contact, 3.5-mm miniature phone jack.
DSUB 9-Pin Data Connector
Ã
External Transmit Audio input, PTT (Push To Talk),
Squelch, and Receive Audio output signals may be obtained
from this connector for use with accessories such as a data
transmission/reception modem, etc.
3
Operating Manual Reprint
OPERATION
Power ON/OFF
Turn the VOLUME/POWER knob clockwise to turn on the radio. The active display and channel indicators will become illuminated, indicating the status of the radio. The channel indicated
will be the same one on which you were operating when the radio was last turned off.
Setting the Channel
In 4-channel versions, press the CHANNEL button to change
channels.
In 40-channel versions, the display will show either a channel
number or a Scan Mode indicator (Sc, Ur, SP or UP). If a Scan
Mode indicator is displayed, press the SCAN button momentarily so that a channel number is displayed; then press either the
UP (p) or DOWN (q) button to change channels.
Setting the Volume
Rotate the VOLUME/POWER knob clockwise to increase the
volume level. If no signal is present on which to adjust the volume level, push and hold in the MONI button for two seconds;
the yellow “MONI” indicator will blink, and either background
noise or a voice signal will be heard. You may now adjust the
VOLUME/POWER knob for a comfortable listening level.
When you are done, press the MONI button momentarily to return to silent monitoring.
Transmitting
To transmit, wait until the “TX/BUSY” indicator is off (this indicates that the channel is not in use). Then press the PTT (Push-
To-Talk) switch on the side of the microphone; while holding in
the PTT switch, speak in a normal voice level across the face of
the microphone. During transmission, the red “TX/BUSY” indicator will glow steadily. When you are done transmitting, release the PTT switch; the VX-2000 will revert to the “receive”
mode.
The remaining instructions apply to 40-channel trans-
Scanning
To activate scanning on your radio, first place the microphone in
its hanger. Now press the SCAN button momentarily. The radio
will scan in one of four available Scan Modes (detailed below),
and will halt when a signal is received which contains the correct
code to open your squelch. Scanning will resume automatically
either after a preset interval of a few seconds, or after the other
station stops transmitting (depending on how your radio was programmed).
The four Scan Modes, and their corresponding displays, are:
Display Scanning function
Sc Scan all channels
Ur Scan only user-selected channels
SP Monitor one channel plus dealer-designated Priority Channel(s)
UP Scan user-selected channels plus uer-designated Priority Channel(s)
The user-selected channels for the Ur and UP Scan Modes are
ones you can set up yourself, as described at the right. The
“Priority” channels are those on which signals will take priority over signals received on other channels; that is, if a signal
appears on a Priority Channel while another appears on a nonpriority channel, the Priority Channel signal will be heard, and
not the other.
Up to two of the installed channels may be designated by your
Dealer as pre-programmed Priority Channels for the SP mode
(the radio will not indicate which they are), and you can additionally program any two channels as “User Priorities” for the
UP mode. In the SP mode, the non-priority channel will be the
last one displayed.
When a Scan Mode is displayed, you can select another by pressing the SEL/PRI button repeatedly (the display will cycle through
the above selections). Note that the radio will not scan if the
microphone is not in its hanger.
ceiver versions only
Special Transmitter Functions
If your VX-2000 is programmed for Busy Channel LockOut, the transmitter will not activate when the PTT switch is
pressed unless the “TX/BUSY” indicator is off (so as to prevent interference to other users of the same channel).
If the selected channel has been programmed for Automatic
Time-Out, you must limit the length of your transmissions.
While transmitting with this feature activated, a “beep” will
sound ten seconds before the timer expires, and then another
“beep” sound as the timer expires: the “TX/BUSY” indicator will shut off, and transmission will cease. Release the
PTT switch, listen for a moment, then press PTT again to
resume transmission. This feature prevents interference to
other users caused by a microphone which accidentally is
stuck in the “transmit” position (wedged between seats of a
car, etc.).
4
Operating Manual Reprint
USER PROGRAMMABLE CHANNEL SELECTIONS
You can program a list of channels to be scanned, and up to two
channels to be monitored on a “priority” basis. Your selections
will be maintained in memory until you change or delete them.
Setting of these channels involves two small “Dot” indicators at
the top of the channel display field. The Dot to the left of the first
digit is the “P” (Priority) indicator, while the Dot to the left of
the second digit is the “E” (Enable for Scanning) indicator.
To create or modify the Scan and Priority selections, first turn
the radio off. Now press and hold in the SCAN button while you
turn the transceiver back on; continue to hold the SCAN button
in for two seconds after the radio has come on, then you may
release it.
Now press the UP (p) or DOWN (q) button repeatedly, and
note whether or not the “E” (right dot) or “P” (left) dots appear
on any of your channels. If a dot appears by any channel, it means
that it has been designated as either a Scan-Enabled or Priority
channel, respectively.
To enable or disable a channel from the User Scan list, press the
SEL/PRI button momentarily. The “E” dot will appear or disappear, as appropriate.
To change the Priority Channels, first cancel both by selecting
either, and then pressing the SEL/PRI button momentarily. Now
select the channel you wish to designate as the 1st Priority Chan-
nel, and hold in the SEL/PRI button for 2 seconds, until a beep
sounds and the “P” indicator blinks. If you wish to designate a
2nd Priority Channel, move to that channel, and again hold in
the SEL/PRI button for 2 seconds; this time, the “P” indicator
will glow, but will not blink.
If you have deleted a channel from Priority status, you must reenable it for scanning if you want it to be included on your Scan
List. Press the SEL/PRI button momentarily to do this.
Coded Squelch - the MONI Button
Your transceiver may be programmed so that when the microphone is removed from its hanger, coded squelch is defeated, and you can hear any signal on the channel (the yellow “MONI” indicator will be lit). You can get the same
result, without lifting the microphone, by pressing the MONI
button momentarily. To avoid listening to unnecessary chatter, keep the microphone in its hanger, and press the MONI
button when necessary to turn the yellow indicator off (unless you want to listen to other calls on the channel).
Holding the MONI button in for two seconds defeats both
the coded squelch and noise squelch, so background noise
can be heard (the “MONI” indicator will blink in this case).
Press the MONI button momentarily to return the yellow
indicator to its previous state (either off or steadily on).
OPTIONAL ACCESSORIES
CE-20 Programming Software (for IBM PC/compatibles only)
VPL-1 Programming Cable
T9101411 Radio-to-Radio Cloning Connection Cable
FP-1025A Heavy-Duty (20A) AC Power Supply
MD-11A8J Desktop Microphone
MH-600D DTMF Back-lit Microphone w/Autodial
MLS-100 External Loudspeaker
LF-1 DC Line Filter
VTM-20 VX-Trunk II Trunking Mobile Logic Board
F2D-4A/B 2-Tone Decoder Unit
FTE-18 ANI Unit
5
Operating Manual Reprint
J1003 DSUB 9-Pin Data Connector Pin Assignment
ÃÄ Â Á À
È Ç Æ Å
À SQ: Squelch Signal Output
Carrier In: Active High (5 V / 47 kΩ)
Á RX_AUD_OUT: Received Audio Output (Two choices available)
Á-1 De-Empasized Audio Output: 100 mV / 10 kΩ
This output level's default state is fixed at the factory by
having no jumper at JP1003 and soldering the jumper at
JP1002 on the MAIN Unit.
Á-2 Flat / Unmuted Audio Output: 250 mV / 10 kΩ
(Unsolder the jumper at JP1002 and solder a jumper at JP1003
on the MAIN Unit to activate Á-2)
 EXT_MIC: External MIC Audio Input (Two choices available)
Â-1 Pre-Emphasized / IDC / Splatter Filtered Audio Input:
2.5 mV / 600 Ω
This input is fixed at the factory by attaching capacitor
C1254 across JP1005 and soldering a jumper at JP1004
on the MAIN Unit.
Â-2 Flat (Non-Pre-Emphasized) Audio Input: 650 mV / 10 kΩ
(Remove the jumper at JP1004 and solder a jumper across
JP1005 on the MAIN Unit to activate Â-2)
à Not Used
Ä GND: Ground
Å A_OUTPUT: Accessory Output (Two choices available)
Å-1 Not Used
This is the default setting at the factory (no jumper across
JP1001 on the MAIN Unit).
Å-2 Accessory Output: Open Collector Output
"A" Lamp ON: Low, "A" Lamp OFF: Open
Maximum voltage: 13.8 V, Maximum sink current 5 mA
(Solder a jumper at JP1001 on the MAIN Unit to activate Å-2)
Æ PTT: External PTT Signal input
GND: TX, Open: RX
Ç 5 V
Switched and regulated DC 5 V output for supplying
power to an accessory.
Maximum output current is 50 mA.
È Not Used
6
Specifications
General
Frequency Range (version): 400 ~ 430, 450 ~ 480 or 480 ~ 512 MHz (UHF vers. A/D/F, respectively)
No. of Channels & Spacing: 4 or 40 channels 25-kHz, 12.5-kHz spacing
Modes of Emission: 16K0F3E ,11K0F3E
Frequency Stability: ±0.00025%
Antenna Requirements: 50 ohms, unbalanced (SO-239 socket)
Voltage Requirements: 11.8 V to 15.6 V DC, negative ground
Current Consumption (approx.): 250 mA Stby, 200 mA Rx, 6.5 A Tx
Operating Temperature Range: -22 °F to +140 °F (-30 °C to +60 °C)
Size (WHD, approx.): 6¼ ´ 1½ ´ 4¼ inches (160 ´ 40 ´ 105 mm)
Weight (approx.): 1.9 lbs. (0.85 kg)
Receiver
Receiver Circuit Type: Double-Conversion Superheterodyne
Intermediate Frequencies: 43.95 MHz , and 450 kHz (all models)
Sensitivity: 0.2/0.25 µV for 12-dB SINAD
0.3/0.35 µV for 20 dB NQ
Hum & Noise Ratio: Better than 45 dB for 25-kHz/step,
Better than 40 dB for 12.5-kHz/step
Adjacent Channel Selectivity: >70 dB for 25-kHz/step,
>60 dB for 12.5-kHz/step
Intermodulation Distortion: Better than 65 dB
Spurious Rejection: Better than 65 dB
External Audio Output Power: 2 watts into 8 ohms with <10% THD
Transmitter
Power Output: 25/5 watts (high/low, programmable)
Modulation Type/Deviation: Frequency Modulation, ±5 kHz (±2.5 kHz )
Hum & Noise Ratio: Better than 45 dB for 25-kHz/step,
Better than 40 dB for 12.5-kHz/step
Modulation Distortion: Less than 5%
Spurious Emissions: Better than 65 dB (below carrier)
Microphone Impedance: 600 ohms
Specifications are subject to change without notice or obligation.
7
Exploded View & Miscellaneous Parts
VXSTD P/NREF.
U24208001 TAPTITE SCREW M2.6X8 (Lot. 1~3) 1
À
U20208001 BINDING HEAD SCREW M2.6X8 (Lot. 4~) 1
Á
U20306002 BINDING HEAD SCREW M3X6NI 4
U23205001 TAPTITE SCREW M2.6X5 4
Â
U23206001 TAPTITE SCREW M2.6X6 3
Ã
U24306002 TAPTITE SCREW M3X6NI 5
Ä
U31206007 OVAL HEAD SCREW M2.6X6B 7
Å
U24308001 TAPTITE SCREW M3X8 1
Æ
RA0034900
RUBBER KNOB (4CHANNEL)
CP6003001
PANEL-SUB A ASSY
Description
DISPLAY-1 Unit
MAIN Unit
Qty.
P1090654
CONNECTOR
Å
Ä
Å
VXSTD P/N
Q0000062
Q0000008 (Lot. 8~)
T9021810 DC CABLE 1
RA0060100
CASE
Description
FUSE 10A 2
T9206675
WIRE ASSY
Å
Ä
Ä
Á
Á
À
Æ
Å
Ä
P1090984
CONNECTOR
Qty.
Å
RA0015600
RUBBER KNOB (40 CHANNEL)
Å
R6054387B
SPECIAL NUT
RA001330A
KNOB
VR Unit
MIC Unit
Å
NAME PLATE
RA0013900 (EXPORT)
RA0014000 (VTX(USA))
Ã
Ã
Ã
Â
Â
Â
Â
M4090122
SPEAKER
CP6007001
PANEL-SUB B ASSY
Ä
RA0056000
RA005600A (Lot. 3)
RA005600B (Lot. 4~)
DISPLAY-2 Unit
RA00560AB (THA1: Lot. 33~)
RA00560AC (THA: Lot. 47~)
RA005600C (Lot. 47~)
CHASSIS
Non-designated parts are available
only as part of a designated assembly.
Á
Á
8
VX-2000U 4ch Front Panel Block Diagram
Block Diagram
VX-2000U 40ch Front Panel Block Diagram
9
Block Diagram
Note:
10
VX-2000U Main Unit Block Diagram
Block Diagram
11
Block Diagram
Note:
12
VX-2000U 4ch Front Interconnection Diagram
Interconnection Diagram
(T9206689A: Lot 6~)
13
Interconnection Diagram
VX-2000U 40ch Front Interconnection Diagram
(T9206689A: Lot 6~)
14
Circuit Description
Receive Signal Path
Incoming RF from the antenna jack is delivered
to the MAIN Unit, and passes through a low-pass
filter consisting of coils L1001, L1002, L1004, and
L1006, capacitors C1002, C1006, C1009, C1017,
C1019, C1022, C1041, and C1046, and antenna
switching diodes D1002 (UM9957F) and D1005
(RLS135), then passed to the receiver front end.
Signals within the frequency range of the transceiver then enter a varactor-tuned band-pass filter consisting of coils L1008, L1010, L1011, L1013,
L1014, L1015, L1016, L1017, L1018, L1019, L1020,
L1023, and L1024, capacitors C1045, C1052, C1054,
C1056, C1058, C1068, C1072, C1073, C1086, C1090,
C1091, C1093, C1094, C1095, C1097, C1100, C1101,
C1105, C1106, C1110, and C1111, plus diodes
D1007, D1008, D1011, D1012, D1013, and D1014
(all HVU350). After bandpass filtering, the in-
band RF signals are amplified by RF preamplifier Q1012 (2SC4227).
Buffered output from the VCO is amplified by
Q1038 (2SC5107) to provide a pure 1st local signal between 406.05 and 436.05 MHz for injection
to the 1st mixer Q1021 (SGM2016). The result-
nal within Q1029. The 2nd IF then passes through
the ceramic filter CF1001 (CFWM450G ) or
CF1002 (CFWM450E) to strip away unwanted
mixer products, and then is applied to the limiter amplifier in Q1029, which removes amplitude
variations in the 450 kHz IF. Speech detection by
the ceramic discriminator CD1001
(CDBM450C24T) is then performed, converting
the second IF into an audio signal.
Detected audio from Q1029 is amplified by
Q1017-1 (NJM2904V) and then applied to the deemphasis network, consisting of capacitors
C1084/C1089, resistors R1038/R1049, and Q10074 (NJM2902V). The de-emphasized audio signal is then applied to CTCSS subsystem IC Q1009
(MX165BDW), which contains the TX/RX audio
filter, CTCSS decoder, and CTCSS encoder; if a
CTCSS tone is present on the incoming signal, it
is removed by the high-pass filter in Q1009. The
processed signal passes through the audio mute
gate Q1008 (DTC124EK) and the volume control, then enters the audio power amplifier Q1003
(TDA2003H), which provides up to 2 Watts to
the external speaker jack or internal speaker.
ing 43.95 MHz 1st IF then passes through monolithic crystal filter XF1001, which strips away all
but the desired signal, and the signal is then
amplified by Q1026 (2SC4215Y). The amplified
1st IF signal is then applied to FM IF subsystem
IC Q1029 (BA4116FV), which contains the 2nd
mixer, 2nd local oscillator, a limiter amplifier, and
a noise amplifier.
A 2nd local signal is generated by PLL reference/2nd local oscillator Q1046 (2SC4116GR),
using the 14.5 MHz crystal X1002 in a 3rd-overtone mode as a reference. This signal is mixed
with the 43.95 MHz IF at Q1029 to produce the
450 kHz 2nd IF when mixed with the 1st IF sig-
Squelch Control
The squelch circuitry consists of a noise amplifi-
er, band-pass filter, and noise detector within Q1029,
plus control circuitry within Q1039 (MB89677).
When no carrier is received, noise at the output of the detector stage in Q1029 is amplified,
band-pass filtered and detected by Q1029. The
resulting DC squelch control voltage is passed
to pin 33 of microprocessor Q1039. When no carrier is being received, pin 33 of Q1039 remains
low, signaling pin 5 of Q1039 to keep the green
"BUSY" LED off, and simultaneously signaling pin
19 of Q1039 to command AF mute gate Q1008
(DTC124EK) to block receiver audio.
15
Circuit Description
When a carrier appears at the discriminator,
noise is removed from the output, causing pin
33 of Q1039 to go high, in turn causing the "BUSY"
LED and audio output lines to turn on. The microprocessor then checks for CTCSS information.
If CTCSS decode is not activated, or if CTCSS
decode is activated and a signal carrying a matching tone is received, the microprocessor allows
audio to pass through AF mute gate Q1008 and
audio amplifier Q1003 to the speaker.
Transmit Signal Path
Speech input from the microphone is delivered
to the MAIN Unit, where it passes through the preemphasis network (R1016 and C1031). The preemphasized speech signal proceeds through the
AF high-pass filter at Q1009, then is applied to
the IDC (Instantaneous Deviation Control) at
Q1016-3 (NJM2902V), with deviation level being
set by potentiometer VR1001. The audio then passes to a splatter filter in sections 1 and 4 of Q1016,
which filters out high-frequency components
which could result in over-deviation.
The processed audio is mixed with the CTCSS tone (if activated) generated by CTCSS subsystem IC Q1009, then delivered to D1031
(1SV230) for frequency modulation of the PLL
carrier (at the transmitting frequency) up to ±5
kHz from the unmodulated carrier frequency.
Automatic Transmitter Power Control
RF output from the final amplifier is sampled
by C1039 and C1051 and rectified by D1006
(1SS321). The resulting DC voltage is fed through
Automatic Power Controller Q1014 (2SB1143S),
Q1015 (2SC4116GR), and Q1017-2 to effect control of the gain of transmitter PA Q1011. The microprocessor, Q1039, issues commands for setting
"HIGH" or "LOW" power output.
Transmit Inhibit
When the transmit PLL is unlocked, pin 2 of
PLL IC Q1049 (SC370651F) goes to logic "low"
level. The resulting DC unlock control voltage
switches off the TX inhibit switch Q1022 (1MZ1),
which interrupts the supply voltage to the transmitter PA, Q1011, thus disabling the transmitter.
Spurious Suppression
Generation of spurious products by the transmitter is minimized by the fundamental carrier
frequency being equal to the final transmitting
frequency, modulated directly in the transmit
VCO. Additional harmonic suppression is provided by a low-pass filter consisting of L1001,
L1002, L1007, C1002, C1006, C1009, C1017,
C1019, C1036, and C1053, resulting in more than
60 dB of harmonic suppression prior to delivery
of the RF signal to the antenna jack.
The modulated signal from the VCO, Q1047
(2SC5107), is buffered by Q1038 and Q1044 (both
2SC5107). The low-level transmit signal is then
amplified by Q1028 and Q1031 (both 2SC3357),
then applied to the final amplifier, Q1101
(M57729H), providing 25 Watts of transmitter
power. The transmit signal then passes through
the antenna switch, D1003 (MI407), and low-pass
filter (which suppresses harmonic spurious radiation) before delivery to the antenna jack.
16
PLL Frequency Synthesizer
The Phase-Locked Loop (PLL) circuitry on the
MAIN Unit includes VCO Q1047, VCO buffer
Q1044, and PLL subsystem IC Q1049, which includes a reference divider, serial-to-parallel data
latch, programmable divider, phase comparator,
and charge pump.
Stability of the reference oscillator is maintained by a regulated 5 Volt supply, which includes Q1001 (MM1216EN), Q1002
Circuit Description
(2SB1201STP-FA), Q1040 (2SC4116GR), and
D1029 (02CZ5.6Y), with temperature compensation provided by thermistors TH1003/TH1004
and capacitors associated with the 14.5 MHz reference crystal, X1002.
In the receive mode, VCO Q1047 oscillates
between 406.05 and 436.05 MHz, according to the
transceiver version and the programmed receiving frequency. The VCO output is buffered by
Q1044, and applied to the prescaler section of
Q1049. There the VCO signal is divided by 64 or
65, according to a control signal from the data
latch section of Q1049, before being applied to
the programmable divider section of Q1049. The
data latch section of Q1049 also receives serial
dividing data from the microprocessor, Q1039,
which causes the pre-divided VCO signal to be
ference between the signals derived from the
VCO and the crystal reference oscillator. The
VCO is thus phase-locked to the crystal reference
oscillator. The output of the VCO is then delivered to the first mixer via buffer amplifier Q1044.
For transmission, the VCO Q1047 oscillates
between 450 and 480 MHz, according to the model version and the programmed transmit frequency. The remainder of the PLL circuitry is shared
with the receiver section. However, the dividing
data from the microprocessor is such that the
VCO frequency is at the actual transmitting frequency (rather than being offset by the IF, as in
the receiving case). Also, the VCO is modulated
by the speech audio applied to D1031 (1SV230),
as described previously.
Receive and transmit buses select which VCO
further divided in the programmable divider section, depending on the desired receive frequency, so as to produce either a 10 kHz or 12.5 kHz
derivative of the current VCO frequency.
Meanwhile, the reference divider section of
Q1049 divides the 14.5 MHz crystal reference frequency by 1450 (or 1160) to produce the 10 kHz
(or 12.5 kHz) loop reference (respectively). The 10
kHz (or 12.5 kHz) signal from the programmable
divider (derived from the VCO) and that derived
from the reference oscillator are applied to the
phase detector section of Q1049, which produces
a pulsed output with pulse duration depending
on the phase difference between these input signals. The pulse train is filtered to DC and returned
to varactors D1038 and D1039 (both 1SV276).
Changes in the level of the DC voltage applied
is made active via Q1050 (DTC124EU). FET
Q1043 (2SK880GR) buffers the VCV line for application to the tracking bandpass filters in the
receiver front end.
Push-To-Talk (PTT) Transmit Activation
The PTT switch on the microphone is connected to pin 24 of microprocessor Q1039, so that
when the PTT switch is closed, pin 35 of Q1039
goes low. This signals the microprocessor to activate the TX/RX controller Q1004 (IMH6), which
then disables the receiver by interrupting the 9
V supply bus at Q1006 (DTB123YK) to the receiver front-end, FM IF subsystem IC, and receiver VCO circuitry. At the same time, Q1005
(DTB123YK) activates the transmit 9 V supply
line to enable the transmitter.
to the varactors affect the reactance in the tank
circuit of the VCO, changing the oscillating frequency of the VCO according to the phase dif-
17
Circuit Description
Channel Selection & Display
(4-channel version)
The CHANNEL button on the front panel causes
microprocessor Q1039 to select the operating frequency and CTCSS frequency data from serial
EEPROM Q1048 (BR93LC66AF). The operating
frequency data is in the form of PLL dividing
ratios, which are passed to the PLL IC on the
MAIN Unit via strobe, data, and clock outputs on
pins 43, 42, and 41 respectively. The channel digit
display data from the microprocessor is strobed
by pin 46 to display latch Q2002 (BU4094BCFV)
on the DISPLAY-1 Unit, which decodes the data
and drives the four channel LEDs and the function indicator LEDs.
Channel Selection & Display
(40-channel version)
The UP and DOWN buttons on the front panel
cause microprocessor Q1039 to select the operating frequency and CTCSS frequency data from
serial EEPROM Q1048. The operating frequency
data is in the form of PLL dividing ratios, which
are passed to the PLL IC on the MAIN Unit via
strobe, data, and clock outputs on pins 43, 42,
and 41 respectively. The channel digit display
data from the microprocessor is strobed by pin
46 to display latch Q3001 (DN8657S) on the DIS-
PLAY-2 Unit, which decodes the data and drives
the two 7-segment LEDs and the function indicator LEDs.
18
Alignment
The VX-2000 is carefully aligned at the factory for the specified performance across the designed frequency range. Realignment should,
therefore, not be necessary except in the event of
a component failure, or when altering the frequency range (“version”).
The following procedures cover the sometimescritical and tedious adjustments that are not normally required once the transceiver has left the
factory. However, if damage has occurred and
some parts subsequently are replaced, alignment
may be required in order to restore the original
alignment. If a sudden problem occurs during otherwise normal operation, it is likely due to part
failure, and realignment should be performed only
after the faulty component has been replaced.
All component replacement and service
should be performed only by an authorized
Vertex representative, or the warranty policy
may be voided. Vertex service technicians are experienced with the circuitry, and are fully
equipped for part replacement and alignment.
When any repairs are completed, Vertex service
technicians perform comprehensive performance
checks to ensure that total transceiver system performance complies with each and every specification for this product.
Those who undertake any of the following
alignment procedures are cautioned to proceed
at their own risk. Problems caused by unauthorized attempts at realignment are not covered by
the warranty policy covering this transceiver.
Also, Vertex reserves the right to change circuits
and alignment procedures, in the interest of improved performance, without notifying owners.
Under no circumstances should any alignment
be attempted unless the normal function and op-
any/all faulty components replaced, and realignment determined to be absolutely necessary.
Required Test Equipment
The following test equipment (and thorough
familiarity with its correct use) is necessary for
complete realignment. Correction of problems
caused by misalignment resulting from the use
of improper test equipment is not covered by our
warranty policy.
While most steps do not require all the test
equipment listed, the interactions of some adjustments may require that more complex adjustments be performed afterwards. Do not, therefore, attempt to perform only a single step unless it is clearly isolated electrically from all other steps. Have all test equipment ready before
beginning, and follow all of the steps in a section
in the order presented.
r RF Signal Generator with calibrated output to
550 MHz
r Deviation Meter (linear detector)
r In-line Wattmeter with 5% accuracy at 550 MHz
r 50-W Dummy Load with a power rating of 50
W at 550 MHz
r Regulated DC Power Supply, adjustable from
10 V to 17 V DC at 10 A
r Frequency Counter with 0.2 ppm accuracy at
550 MHz
r AF Signal Generator
r DC Voltmeter, high impedance
r SINAD Meter
r IBM PC
Windows® v3.1 (or later) installed
r Vertex VPL-1 Connection Cable and CE-20
Channel Programming Diskette
r UHF Sampling Coupler
®
/compatible computer with Microsoft
eration of the radio are fully understood, the cause
of the malfunction has been clearly pinpointed and
19
Alignment
Alignment Preparation & Precautions
Before beginning align"ment, connect the transceiver to the PC using the VPL-1 Connection Cable, and upload the current frequency data from
the customer’s radio to the computer; save this
information to disk so that it can be downloaded
to the radio again after alignment is completed.
Next, refer to the label at the rear of the bot-
50 W
Dummy Load
In-Line
Wattmeter
Deviation
meter
Frequency
Counter
RF Sampling
Coupler
CT-71 Connection
cable
COM Port
RF Signal
Generator
Transceiver
AF
Generator
Power Supply
13.8 V
tom cover of the radio to determine its “version”
(frequency range); using the CE-20 software, program the four “Test” simplex channels shown in
the table below, as appropriate for the radio version you are working with:
Channel
1
2
3
4
Version “A”
400.000 MHz
415.000 MHz
430.000 MHz
430.000 MHz
Version “D”
450.000 MHz
465.000 MHz
480.000 MHz
480.000 MHz
Version “D”
450.000 MHz
465.000 MHz
480.000 MHz
480.000 MHz
Download this data to the transceiver under test.
Note: When alignment is finished, you may wish to
save these alignment channels as a disk file for
future service work. Make certain to re-load the
original channel data (uploaded from the radio
prior to servicing) into the transceiver, and complete a final performance check, before returning the equipment to the customer.
A 50-W dummy load and in-line wattmeter
must be connected to the rear-panel antenna jack
in all procedures which require transmission.
Correct alignment is not possible without a re-
Alignment Setup
After completing one alignment step, read the
following step to determine whether or not the
same test equipment will be required. If not, remove the test equipment (except dummy load
and wattmeter) before proceeding.
Correct alignment requires that the ambient
temperature be the same as that of the transceiver, and that this temperature be held constant
between 68°F and 86°F (20°C and 30°C). When
the transceiver is brought into the shop from hot
or cold air, it should be allowed time to come to
room temperature before alignment is attempted. All test equipment should similarly be thoroughly warmed up.
Whenever possible, alignments should be performed with oscillator shields and circuit boards
firmly affixed in place.
Note: Signal levels in dB referred to in these align-
ment procedures are based on 0 dBµ = 0.5 µV
(closed circuit).
sistive 50-W termination for the transmitter.
Be certain that your power supply delivers
13.8 VDC, as measured directly at the radio's DC
input plug, during transmitter tests. Any voltage drop in the cable, or due to the loading on
the power supply, must be compensated to 13.8
VDC for accurate alignment.
20
Connect the test equipment as shown in the
pictorial above.
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