Vertex VX-920 Series User manual

1
VX-920/-920E VHF series Service Manual
Contents
Specifications ...................................................................................................................................................... 2
Exploded View & Miscellaneous Parts .......................................................................................................... 3
Block Diagram .................................................................................................................................................... 5
Circuit Description............................................................................................................................................. 7
Alignment .......................................................................................................................................................... 11
Board Units (Schematics, Layouts & Parts)
Main Unit .................................................................................................................................................... 15
Display Unit ............................................................................................................................................... 43
Cable Unit .................................................................................................................................................. 53
SRX-3 Unit (Option)................................................................................................................................. 55
©2011 VERTEX STANDARD CO., LTD. EC033N90G
VHF Band
Service Manual
VX-920/-920E Series
Introduction
This manual provides the technical information necessary for servicing the VX-920/-
920E Series Transceiver.
Servicing this equipment requires expertise in handing surface-mount chip compo-
nents. Attempts by non-qualified persons to service this equipment may result in
permanent damage not covered by the warranty, and may be illegal in some coun-
tries.
Two PCB layout diagrams are provided for each double-sided board in this trans-
ceiver. Each side of the board is referred to by the type of the majority of components
installed on that side (“Side A” or “Side B”). In most cases one side has only chip
components (surface-mount devices), and the other has either a mixture of both chip
and leaded components (trimmers, coils, electrolytic capacitors, ICs, etc.), or leaded
components only.
As described in the pages to follow, the advanced microprocessor design of the VX-
920/-920E Series Transceiver allows a complete alignment of this transceiver to be
performed without opening the case of the radio; all adjustments can be performed
from the front panel, using the “Alignment Mode” menu.
While we believe the information in this manual to be 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.
Important Note
After Lot.13 of this transceiver was assembled using Pb (lead) free solder, based on the RoHS specification.
Only lead-free solder (Alloy Composition: Sn-3.0Ag-0.5Cu) should be used for repairs performed on this apparatus.
The solder stated above utilizes the alloy composition required for compliance with the lead-free specification, and
any solder with the above alloy composition may be used.
VERTEX STANDARD CO., LTD.
4-8-8 Nakameguro, Meguro-Ku, Tokyo 153-8644, Japan
VERTEX STANDARD U.S.A. Inc.
6125 Phyllis Drive, Cypress, California 90630, U.S.A.
YAESU UK LTD.
Unit 12, Sun Valley Business Park, Winnall Close
Winchester, Hampshire, SO23 0LB, U.K.
VERTEX STANDARD HK LTD.
Unit 1306-1308, 13F., Millennium City 2, 378 Kwun Tong Road,
Kwun Tong, Kowloon, Hong Kong
VERTEX STANDARD (AUSTRALIA)PTY., LTD.
Tally Ho Business Park, 10 Wesley Court, East Burwood, VIC, 3151

2VX-920/-920E VHF series Service Manual
Specifications
General
Frequency range: 134-174 MHz
Channel / Group: 48 CH / 3 Groups (w/o LCD version)
512 CH / 32 Groups (w/ LCD version)
Channel Spacing: 12.5/15/20/25/30 kHz
PLL Stepping: 1.25/2.5/5/6.25/7.5 kHz
Power Supply Voltage: 7.4 V
Current Consumption: 30 mA (Standby w/saver)
(Approx. @7.4 V) 75 mA (Standby)
200 mA (Receive)
1.7 A (Transmit)
Battery Life (Approx.): 7 hours (w/ FNB-V86LI)
12 hours (w/ FNB-V87LI)
Operating Temperature Range: –22 °F to +140 °F (–30 °C to +60 °C)
Frequency Stability: ±2.5ppm
Case Size (W x H x D): 2.24” x 5.24” x 1.48” (57 x 133 x 37.5 mm)
Weight (Approx.): 13.1 oz (370g) (w/FNB-V86LI, ATV-8B, CLIP-920)
Receiver (Measurement per TIA/EIA-603)
Circuit Type: Double Conversion Super-heterodyne
Sensitivity (12dB SINAD): 0.25 μV/0.32 μV(W/N)
Adjacent Channel Selectivity: 75/70 dB (W/N)
Intermodulation: 75/70 dB (W/N)
Spurious Response Rejection: 80 dB
Num & Noise: 48/42 dB (W/N)
Audio output: 700 mW @ 16 ohms 5% THD
Spurious Emissions: –57 dBm
Transmitter (Measurement per TIA/EIA-603)
RF Power Output: 5/2.5/1/0.25 W
Modulation Type: Direct FM (16K0F3E/11K0F3E)
Maximum Frequency Deviation: ±2.5/±4.0/±5.0 kHz
FM Hum & Noise: 45/40 dB (W/N)
Audio Distortion: Less than 3% @ 1kHz
Spurious Emissions: –36 dBm @under 1 GHz
–30 dBm @above 1 GHz
Specifications subject to change without notice or obligation.

3
VX-920/-920E VHF series Service Manual
Exploded View & Miscellaneous Parts
Non-designated parts are available only as
part of a designated assembly.
RA0993500
LATCH PLATE
RA0688700
LATCH NAIL
RA0745400 (x2 pcs)
COIL SPRING
RA060170B
ROTARY KNOB
(VOL)
RA068970A
FRAME
RA0689100
LIGHT GUIDE
G6090163
LCD
RA0699300
SPONGE RUBBER (LCD)
MAIN UNIT
RA060450B
SPECIAL NUT (M)
RA060460B
SPECIAL NUT (L)
RA0603600 (x2 pcs)
O RING (1x4.2)
RA0603700 (x2 pcs)
O RING (1.8x7)
RA0607300
O RING (1.8x5.3)
RA0688800
COVER (BACK)
RA068950B
COVER (ACS)
RA0663600
GASKET (CASE)
RA0663500
GASKET (ACS)
RA0727900
HOLDER PLATE (MIC1)
CP8199001(Waterproof:STD)
CP8199002(Waterproof:MIL 6ft/3h)
REAR CASE ASSY
(O RINGx2pcs, SHEET)
RA0689600
WASHER
CP8249003 (Waterproof:STD)
CP8249006 (Waterproof:MIL 6ft/3h)
PANEL ASSY (16 KEY)
RA0698000
REFERECTOR SHEET
RA0697900
SHEET (FET)
RA0738800 (x2 pcs)
PAD (MIC3)
RA0681900
HOLDER PLATE (POW)
T9207204
WIRE ASSY
RA0664000
RUBBER PACKING (POW)
RA0697400
PAD (ACS) RA0731400 SHEET (9.5X4 M TEX)
DISPLAY UNIT
RA061150B
ROTARY KNOB (CH)


RA060180A
SIDE COVER
























RA0731500
PAD (E1)
CP8249001 (Waterproof:STD)
CP8249004 (Waterproof:MIL 6ft/3h)
PANEL ASSY (NO KEY)
RA0738800
PAD (MIC3)
RA0738800
PAD (MIC3)
RA0993500
LATCH PLATE
RA0688700
LATCH NAIL
RA0745400 (x2 pcs)
COIL SPRING
RA072800A
HOLDER PLATE
(MIC2)



1: w/ LCD, 2: w/o LCD
SPECIAL SCREW
PAN HEAD SCREW
PAN HEAD SCREW
PAN HEAD SCREW
PAN HEAD SCREW
TAPTITE SCREW
TAPTITE SCREW
HEX SOCKET BOLT
TAPTITE SCREW
TAPTITE SCREW
Ref.










(M2.6X5)
M2X3NI
M2X3BSUS #2
M2X3.5 SUS #2
M2X6 SUS #2
M2X4NI
2X10SUS
M2X6BSUS
M2X5NI #2
2X6 SUS #2
Qty.
2
1
1
4
2
8
2
2
51(2)2
12
VXSTD P/N
RA0606200
U00103002
U07230227
U07A35220
U07A60220
U44104002
U44110020
U51106027
U9900094
U9900189
Description
RA0663400
RUBBER PACKING (TOG) RA0712300
HOLDER RUBBER (SW)
RA0731600
PAD (E2)
RA0662800
RUBBER KNOB (16KEY)
RA0663700 (x2 pcs)
INTER CONNECTOR
RA072910A
BLIND SHEET

CP8249002 (Waterproof:STD)
CP8249005 (Waterproof:MIL 6ft/3h)
PANEL ASSY (4 KEY)
RA0993500
LATCH PLATE
RA0688700
LATCH NAIL
RA0745400 (x2 pcs)
COIL SPRING
RA070340A
RUBBER KNOB (4KEY)


4VX-920/-920E VHF series Service Manual
Exploded View & Miscellaneous Parts
Note

5
Block Diagram
VX-920/-920E VHF series Service Manual
Main Unit

6
Block Diagram
VX-920/-920E VHF series Service Manual
Display Unit

7
VX-920/-920E VHF series Service Manual
Circuit Description
1. Circuit Configuration by Frequency
The receiver is a double-conversion superhetero-
dyne type, with a first Intermediate Frequency (IF)
of 50.85 MHz and a second IF of 450 kHz. Incoming
signals from the antenna are mixed with the local
signal from the VCO/PLL to produce the first IF of
50.85 MHz. The signals are then mixed with the 50.4
MHz second local oscillator output to produce the
450 kHz second IF. This is detected to give the de-
modulated signal. The transmit signal frequency is
generated by the PLL VCO, and modulated by the
signal from the microphone. It is then amplified and
sent to the antenna.
2. Receiver System
2-1. Front-end RF amplifier
Incoming RF signals from the antenna are delivered
to the Main Unit and pass through a Low-pass fil-
ter, antenna switching diode D1011 (HVU131), and
a high pass filter, and undesired out-of-band signals
are then removed by a varactor-diode-tuned band-
pass filter D1014, D1015, D1049, and D1050 (all
1SV323). The residual signals are amplified by
Q1022 (2SC5226) and then pass through a varactor-
diode-tuned image-stripping band pass filter D1018
and D1019 (both 1SV323) prior to delivery to the
1st mixer.
2-2. First Mixer
The 1st mixer consists of Q1034 (SPM5001), T1001,
T1002, and T1003. Buffered output from the VCO is
amplified by Q1033 (2SC5226) to provide a pure
first local signal between 184.85 and 224.85 MHz for
injection to the first mixer. The IF signal then passes
through monolithic crystal filter XF1001 (±5.5 kHz
BW) to strip away undesired mixing products.
2-3. IF Amplifier
The first IF signal is amplified by Q1058 (2SC5226).
The amplified first IF signal is applied to FM IF sub-
system IC Q1067 (TA31136FN) which contains the
second mixer, second local oscillator, limiter ampli-
fier, noise amplifier, and S-meter amplifier. The sig-
nal from reference oscillator X1003 is multiplied by
three by Q1067 (TA31136FN), and then is mixed with
the IF signal to produce a 450 kHz second IF.
The second IF signal then passes through the ceramic
filter CF1001 (wide channels), CF1002 (narrow chan-
nels) to strip away all but the desired signal, and is
applied to the limiter amplifier in Q1067
(TA31136FN), which removes amplitude variations
in the 450 kHz IF, before detection of the speech by
the ceramic discriminator CD1001.
2-4. Audio amplifier
Detected audio from Q1067 (TA31136FN) is applied
to Q1032 (AK2345) and is fed to the bandpass filter
inside Q1032 (AK2345).
If an optional signaling unit is installed, Q1078
(NJU4066BV) is set to “OFF,” and the AF signal from
Q1032 (AK2345) is fed to the optional unit. If a sig-
naling unit is not installed, Q1078 (NJU4066BV) is
switched “ON,” and the signal passes through
Q1078 (NJU4066BV). The signal then proceeds
through the de-emphasis stage and the expander at
Q1023 (LA8630M). When the expander function is
off, the signal will be bypassed via Q1016
(NJU4053BV). The output signal of the expander (or
a signal from de-emphasis) goes through AF mute
switch Q1078 (CD4066BV) and is amplified by
Q1077 (LM2902PWR). The signal then proceeds to
Q1030 (NJU4053BV) when the audio equalizer is
“OFF;” if the audio equalizer is “ON,” the signal
from Q1077 (LM2902PWR) passes to the buffer am-
plifier Q1077 (LM2902PWR) for audio equalization
at Q1083 (LM2902PWR) and Q1025/Q1029 (both
CD4052BPWR). The signal then is fed to Q1030
(NJU4053BV). The output from Q1030
(NJU4053BV) is amplified by the AF power ampli-
fier Q1015 (TDA2822) after passing through the AF
volume control Q1020 (M62364FP). The output of
Q1015 (TDA2822) drives the internal speaker.
2-5. Squelch Circuit
There are 13 levels of squelch setting, from “0” to
“12.” The level “0” corresponds to an “open”
squelch. The level “1” is the lowest squelch thresh-
old setting level, and level “11” means tight squelch.
From “2” to “10” are intermediate, increasingly-tight
settings. The level “12” represents carrier squelch.
2-5-1. Noise Squelch
The Noise Squelch circuit is composed of the
bandpass filter at Q1067 (TA31136FN), noise ampli-

8VX-920/-920E VHF series Service Manual
nal passes through the limiter and splatter filter of
Q1032 (AK2345), and is adjusted for proper devia-
tion at Q1020 (M62364FP). The low frequency sig-
nal components (CTCSS, DCS, etc.) are then ampli-
fied by Q1075 (LM2902PWR) and used for direct
modulation of the reference oscillator, TCXO X1003.
The high frequency signal components are ampli-
fied by Q1075 (LM2902PWR), and their level is set
by Q1020 (M62364FP) to establish proper balance
of the level between high- and low-frequency com-
ponents. After that, the signals modulate the trans-
mit carrier via modulator D1027 (1SV286) of the
VCO.
3-2. Noise Canceling Microphone Signal Path
The two signals from the internal microphones
(main and sub) are applied to the positive input (sub)
and to the negative input (main) of Q1076
(LM2904PWR). If the same signal is applied to both
the main and sub inputs, the “main” signal will be
canceled at the output of Q1076 (LM2904PWR), Pin
7. In other words, noise from nearby sources not
directly involved in communication enters the main
and sub input at the same signal and is therefore
canceled out. When a signal is only applied to the
main path, and there is no signal at sub, the main
signal will be passed as-is from Q1076
(LM2904PWR).
3-3. Drive and Final Amplifier Stages
The modulated signal from VCO Q1052 (2SC4227)
is buffered by Q1042 (2SC5226) and amplified by
Q1033 (2SC5226). Then the signal is buffered by
Q1027 (2SC3356) for delivery to the final amplifier
driver Q1021 (2SK3475). The low-level transmit sig-
nal is then applied to Q1010 (2SK3476) for final am-
plification up to 5 watts output power. The transmit
signal then passes through the antenna switch D1012
(HVU131) and is low-pass filtered to suppress har-
monic spurious radiation before delivery to the an-
tenna.
3-4. Automatic Transmit Power Control
The current detector Q1072 (NJM12902V) detects
the current drawn by Q1010 (2SK3476) and Q1021
(2SK3475), and converts the current difference to a
voltage difference. The output from the current de-
Circuit Description
fier Q1071 (2SC4617), and noise detector D1047/
D1048 (both DA221). When a carrier is not being
received, the noise components passed from de-
modulator Q1067 (TA31136FN) are amplified by
Q1071 (2SC4617), fed through bandpass filter Q1067
(TA31136FN), detected as a DC voltage by D1047/
D1048 (both DA221), and applied to pin 16 (the A/D
port) of Q1069 (CPU: LC87F5BP6A). When a car-
rier is received, the DC voltage becomes low because
the noise is compressed. When the detected voltage
to the CPU is high, the CPU stops AF output by set-
ting Q1078 (CD4066BV) “OFF” (by making pin 59
of the CPU “Low” level. When the detection volt-
age is low, the CPU switches Q1078 (CD4066BV)
“ON” by making pin 59 “High,” and the AF signal
is allowed to flow.
2-5-2. Carrier Squelch
The pin 15 (A/D port) of CPU Q1069 (LC87F5BP6A)
detects the RSSI voltage output from Q1067
(TA31136FN) at pin 12, and controls the AF output.
The RSSI output voltage changes according to the
signal strength of carrier; a stronger signal makes
the RSSI voltage higher. The processing of the AF
signal control is same as Noise Squelch, except that
the switching threshold is adjusted so as to be 3 dB
higher than the “tight squelch” sensitivity.
3. Transmitter System
3-1. MIC Amplifier
The AF signal from the internal microphone (pin 4
of J1001) or an external microphone (pin 19) passes
through microphone selection switch Q1001
(NJU4053BV) and is amplified by microphone am-
plifier Q1076 (LM2904PWR), thereafter passing
through the microphone gain controller, Q1020
(M62364FP). The AF signal then passes through
compandor Q1023 (LA8630M). When not using the
compandor, the CPU bypasses the compandor cir-
cuit and feeds the signal to the pre-emphasis circuit.
Q1078 (CD4066BV) becomes “OFF” when an op-
tional signaling unit is attached, and the AF signal
from Q1023 (LA8630M) is redirected via the signal-
ing unit. If a signaling unit is not installed, Q1078
(CD4066BV) becomes “ON,” the signal bypasses
Q1078 (CD4066BV), and it instead is applied to the
pre-emphasis amplifier Q1032 (AK2345). The sig-

9
VX-920/-920E VHF series Service Manual
Circuit Description
tector Q1072 (NJM12902V) is compared with the ref-
erence voltage and amplified by the power control
amplifier Q1072 (NJM12902V). The output from
Q1072 (NJM12902V) controls the gate bias of the fi-
nal amplifier Q1010 (2SK3476) and the driver Q1021
(2SK3475). The reference voltage switches among
four values of TX Power (“High,” “Low3,” “Low2,”
and “Low1”), as controlled by Q1020 (M62364FP).
3-5. PLL Frequency Synthesizer
The frequency synthesizer consists of PLL IC Q1070
(SA7025DK), the VCO, TCXO (X1003), and buffer
amplifier. The output frequency from the TCXO is
16.8 MHz, and the tolerance is ±2.5 ppm (in the tem-
perature range —30 °C to +60 °C).
3-5-1. VCO (Voltage-Controlled Oscillator)
While the radio is receiving, the RX oscillator Q1047
(2SK508) in the VCO generates a programmed fre-
quency between 184.85 and 224.85 MHz as the 1st
local signal. While the radio is transmitting, the TX
oscillator Q1052 (2SC4227) in the VCO generates a
frequency between 134 and 174 MHz (the actual
transmitting frequency). The output from the oscil-
lator is amplified by buffer amplifier Q1042
(2SC5226) and becomes the output of the VCO. The
output from VCO is divided: one part is amplified
by Q1051 (2SC5226) and fed back to the PLL IC at
pin 5. The other is amplified by Q1033 (2SC5226)
and, in case of the reception, it is fed via D1020
(DAN222) to the mixer as the 1st local signal. On
transmit, it is buffered Q1027 (2SC3356), and passed
through D1020 (DAN222) to amplifier Q1021
(2SK2375) and then fed to the final amplifier Q1010
(2SK2376).
3-5-2. VCV (Varactor Control Voltage) Control
The tuning voltage (VCV) of the VCO establishes
the lock range of the VCO by controlling the anode
of a varactor diode using a negative voltage and the
control voltage from PLL IC Q1070 (SA7025DK). The
negative voltage is fed to the varactor diode after
conversion to a negative value at Q1031
(NJM2130F), using the output voltage of the D/A
converter, Q1020 (M62364FP).
3-5-3. PLL
The PLL IC Q1070 (SA7025DK) consists of a refer-
ence divider, main divider, phase detector, charge
pumps and a fractional accumulator. The reference
frequency from TCXO is applied to pin 8 of the PLL
IC Q1070 (SA7025DK) and is divided by the refer-
ence divider. This IC is a decimal point dividing PLL
IC, and the dividing ratio becomes 1/8 of the usual
PLL frequency step. Therefore, the output of refer-
ence divider is 8 times the frequency of the channel
step. For example, when the channel steps are set to
5 kHz, the output of reference divider becomes 40
kHz. The feedback signal from the VCO applied to
5 pin of the PLL IC Q1070 (SA7025DK) is divided
according to the dividing ratio so as to become the
same frequency as that of the output of reference
divider. These two signals are compared by the
phase detector, and a phase difference pulse is gen-
erated. The phase difference pulse and the pulse
from the fractional accumulator pass through the
charge pumps and low-pass filter, producing a DC
voltage (VCV) to control the VCO. The oscillation
frequency of the VCO is therefore locked via the
control of this DC voltage. The PLL serial data from
the CPU Q1069 (LC87F5BP6A) is sent with three
lines of data: SDO (pin 20), SCK (pin 22) and PSTB
(pin 27). The lock condition of the PLL is sent from
the UL (pin 17) terminal, and UL becomes “High”
at the time of a proper lock condition and becomes
“Low” at the time of an unlocked condition. The
CPU always watches over the UL condition, and
when it becomes “Low” (unlocked condition), the
CPU Q1069 (LC87F5BP6A) prohibits transmission
and reception.

10 VX-920/-920E VHF series Service Manual
Circuit Description
Note

11
VX-920/-920E VHF series Service Manual
Alignment
Introduction
The VX-920/-920E series is carefully aligned at the
factory for the specified performance across the fre-
quency range specified for each version. Realign-
ment should therefore not be necessary except in
the event of a component failure, or altering ver-
sion type. All component replacement and service
should be performed only by an authorized Vertex
Standard representative, or the warranty policy may
be void.
The following procedures cover the sometimes crit-
ical and tedious adjustments that are not normally
required once the transceiver has left the factory.
However, if damage occurs and some parts subse-
quently are placed, realignment may be required. If
a sudden problem occurs during normal operation,
it is likely due to component failure; realignment
should not be done until after the faulty component
has been replaced.
We recommend that servicing be performed only
by authorized Vertex Standard service technicians
who are experienced with the circuitry and fully
equipped for repair and alignment. Therefore, if a
fault is suspected, contact the dealer from whom the
transceiver was purchased for instructions regard-
ing repair. Authorized Vertex Standard service tech-
nicians realign all circuits and make complete per-
formance checks to ensure compliance with factory
specifications after replacing any faulty components.
Those who do undertake any of the following align-
ments are cautioned to proceed at their own risk.
Problems caused by unauthorized attempts at re-
alignment are not covered by the warranty policy.
Also, Vertex Standard 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 opera-
tion of the transceiver are clearly understood, the
cause of the malfunction has been clearly pinpoint-
ed and any faulty components replaced, and realign-
ment determined to be absolutely necessary.
The following test equipment (and thorough famil-
iarity with its correct use) is necessary for complete
realignment. Correction of problems caused by mis-
alignment resulting from use of improper test equip-
ment is not covered under the warranty policy.
While most steps do not require all of the equip-
ment listed, the interactions of some adjustments
may require that more complex adjustments be per-
formed afterwards. Do not 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 sec-
tion in the order presented.
Required Test Equipment
RF Signal Generator with calibrated output level
at 200 MHz
Deviation Meter (linear detector)
In-line Wattmeter with 5 % accuracy at 200 MHz
50 Ohm RF Dummy Load with power rating 10
W at 200 MHz
16 Ohm AF Dummy Load (Attention : Audio out-
put is BTL output)
Regulated DC Power Supply (standard 7.5 V DC,
3 A)
Frequency Counter with 0.2 ppm accuracy at 200
MHz
Audio Generator
AC Voltmeter
DC Voltmeter
VHF Sampling Coupler
IBM PC / compatible Computer with Microsoft®
Windows® 95 or later operating system
Vertex Standard CE59 (version 2.06 or later)
Alignment program and CT-109 PC Program-
ming Cable or FIF-10AUSB Interface/CT-108 PC
Programming Cable
: When using the FIF-10A USB Interface, requires
the Windows® 2000 or Windows® XP

12 VX-920/-920E VHF series Service Manual
Alignment
Alignment Preparation & Precautions
A 50-Ohm RF Dummy Load and in-line wattmeter
must be connected to the main antenna jack in all
procedures that call for transmission, except where
specified otherwise. Correct alignment is not possi-
ble with an antenna.
After completing one step, read the following step
to determine whether the same test equipment will
be required. If not, remove the test equipment (ex-
cept dummy load and wattmeter, in connected) be-
fore proceeding.
Correct alignment requires that the ambient temper-
ature be the same as that of the transceiver and test
equipment, and that this temperature be held con-
stant between 68 and 86 °F (20 ~ 30 °C). When the
transceiver is brought into the shop from hot or cold
air, it should be allowed time to come to room tem-
perature before alignment.
Whenever possible, alignments should be made with
oscillator shields and circuit boards firmly affixed
in place. Also, the test equipment must be thorough-
ly warmed up before beginning.
Note: Signal levels in dB referred to in the align-
ment procedure are based on 0 dBmEMF = 1 mV.
Setup the test equipment as shown for transceiver
alignment, apply 7.5 V DC power to the transceiv-
er. Refer to the drawings above for Alignment
Points.
The transceiver must be programmed for use in the
intended system before alignment is attempted. The
RF parameters are loaded from the file during the
alignment process.
In order to facilitate alignment over the complete
switching range of the equipment it is recommend-
ed that the channel data in the transceiver is preset
as the chart below.
TRANSMITTER SECTION ALINGMENT SETUP RECEIVER SECTION ALINGMENT SETUP
The alignment mode is accessed by “Alignment
mode” command from the computer, and the align-
ment tool operates it automatically. During the align-
ment mode, normal operation is suspended. Use
the alignment tool program running on PC.
CHANNEL
BAND-LOW
BAND-MID
BAND-HIGH
FREQUENCY
134.000 MHz
154.000 MHz
174.000 MHz
VX-920
Inline
Wattmeter
Power Supply
7.5 VDC
Deviation
Meter
Frequency
Counter
30 dB PAD
MIC/SP
COM Port or USB Jack
ANT
CT-109 or FIF-10/CT-108
RF
Signal Generator
VX-920
Power Supply
7.5 VDC
MIC/SP
COM Port or USB Jack
ANT
CT-109 or FIF-10/CT-108

13
VX-920/-920E VHF series Service Manual
Alignment
The Alignment Tool Outline
Installation the tool
Install the CE59 (version 2.06 or later) to your PC.
The re-alignment for VX-920/-920E series uses
the “Alignment“ menu of CE59.
Action of the switches
When the transceiver is in the “Alignment mode,“ the
actions of the PTT switch and keys are ignored. All of
the commands are remotely controlled by the PC.
Basic sequence
The data displayed in screen of this tool is tempo-
rary data, and you must take care to ensure the pres-
ervation of the command sequence which is speci-
fied below.
1. Enter the “Alignment mode“
2. Upload data from radio
3. Edit/set alignment data
4. Download data to radio
When you finish one alignment parameter, the tool
will ask you “Save the Aligned Data?“ If you select
“Yes,“ the temporary data will updated. If you se-
lect “No,“ the tool will not update the temporary
data and the setting will return to its original value.
Basic Alignment Mode
The Basic Alignment mode allows you to align the
entire radio. The value of each parameter can be
changed to the desired position by use of the “” /
“” and up/down arrow keys, along with direct
number input and dragging of the PC mouse.
To enter the Basic Alignment Mode, select “Basic
Alignment” in the main “Radio” menu. It will start
to “Upload” the written personalized data from the
radio. Pressing the “OK” button will then start the
Basic Alignment Mode.
Note: when all items are to be aligned, it is strongly
recommended to align them according to following
sequence. Detailed information for each step may
be found in the “Help” file within CE59 (Clone Ed-
itor).
1. RX VCO Tune Voltage (RX VCO)
2. TX VCO Tune Voltage (TX VCO)
3. PLL Reference Frequency (Frequency)
4. RX Sensitivity (RX Tune)
5. Squelch (SQL)
6. TX Power
7. Maximum Deviation <Wide>
8. Maximum Deviation <Narrow>
9. Sub Audio Deviation <CTCSS>
10. Sub Audio Deviation <DCS>
11. Sub Receiver Sensitivity (RX Tune)
BATTERY TERMINAL POLARITY

14 VX-920/-920E VHF series Service Manual
Alignment
CH (C HANNEL - BY -C HANNEL ) Fine Alignment Mode
The CH Fine Alignment Mode allows you to align
the radio separately for every operating channel. The
value of each parameter can be changed to the de-
sired position using the “” / “” and up/down
arrow keys, direct number input, and by dragging
the PC mouse.
To enter the CH Fine Alignment Mode, select “CH
Fine Alignment” in the main “Radio” menu. It will
start to “Upload” the written personalized data from
the radio. Pressing the “OK” button will then start
the CH Fine Alignment Mode.
Note: Detailed information for each step may be
found in the “Help” file within CE59 (Clone Editor).
Note!
Because of the bridge audio amplifier circuit
used in the , it is necessary to
construct and use a simple audio load test
adapter as shown in the schematic diagram,
when conducting receiver alignment steps.
Do not connect either side of the speaker leads
to chassis “ground.”
AF TEST ADAPTER SCHEMATIC
Pin 1: SP (+)
Pin 3: GND
Pin 5: SELECT
Pin 7: CLONE
Pin 9: DISC OUT
Pin 11: VCCP
Pin 13: TXD
Pin 4: BLACK
Pin 5: BLUE
Pin 6: YELLOW
Pin 7: GRAY
Pin 8: GREEN
Pin 9: PURPLE
Pin 10: ORANGE
Pin 12: CLEAR
Pin 13: PINK
Pin 14: BROWN
Pin 11: L_GREEN
Pin 3: SHIELD
Pin 2: RED
Pin 1: WHITE
16-Ohm 2W
27 k-Ohm 2.2 k-Ohm
220 µF
220 µF
10 µF AUDIO GENERATOR
PTT SW
1/2 OUTPUT LEVEL
AF METER
Pin 2: SP (- )
Pin 4: MIC
Pin 6: PTT/ACC
Pin 8: 5V
Pin 10: SEL
Pin 12: RESET
Pin 14: RXD
-
VXSTD P/N: T9207094

15
Main Unit
VX-920/-920E VHF series Service Manual
Circuit Diagram
RX: 0.8 V
TX: 0 V
RX: 2.6 V
TX: 0 V
0 V
RX: 7.4 V
TX: 7.2 V RX: 0 V
TX: 3.0 V
RX: 7.4 V
TX: 7.2 V
RX: 0 V
TX: 1.4 V
PWR ON: 7.4 V
PWR OFF: 0 V
RX: 0 V
TX: 3.0 V
RX: 0 V
TX: 4.3 V
RX: 0 V
TX: 1.5 V
0 V
RX: 0 V
TX: 5.0 V
RX: 0 V
TX: 3.0 V
RX: 3.2 V
TX: 0 V
RX: 1.4 V
TX: 0 V
RX: 7.4 V
TX: 7.1 V
RX: 4.1 V
TX: 0 V
2.6 V @25 °C
PWR ON: 5.0 V
PWR OFF: 0 V
3.5 V
PWR ON: 1.7 V
PWR OFF: 0 V
SAVE ON: 0 V
SAVE OFF: 3.2 V
TX: 0 V
PWR ON: 0 V
PWR OFF: 7.4 V
PWR ON: 5.0 V
PWR OFF: 0 V
RX: 7.4 V
TX: 6.8 V
RX: 7.4 V
TX: 7.2 V
RX: 0 V
TX: 5.0 V
RX: 5.1 V
TX: 4.4 V
RX: 5.1 V
TX: 0.1 V
RX: 0.1 V
TX: 3.3 V
7.4 V
[A]: 3.5 V
[
Center
]: 1.8 V
[B]: 0 V
SW ON: 0 V
SW OFF: 3.6 V
SW ON: 0 V
SW OFF: 3.6 V
SW ON: 0 V
SW OFF: 3.6 V
SW ON: 0 V
SW OFF: 3.6 V
MUTE: 0.9 V
BUSY: 3.4 V
TX: 3.4 V
MUTE: 3.3 V
BUSY: 0.6 V
TX: 0.6 V
3.5 V
5.0 V
RX: –4.8 V
TX: –5.0 V
RX: –1.7 V
TX: –0.9 V
RX: 2.8 V
TX: 0 V
RX: 0 V
TX: 2.9 V
RX: 2.1 V
TX: 2.2 V
RX: 0.7 V
TX: 0.8 V
0.2 V
RX: 2.5 V
TX: 0.7 V
3.5 V
RX: –1.3 V
TX: –0.5 V
RX: –4.1 V
TX: –4.6 V
RX: 0.1 V
TX: 3.3 V
RX: 3.4 V
TX: –4.5 V 0.1 V
2.2 V
0.8 V
RX MAIN: 0 V
RX SUB: 2.7 V
TX: –0.5 V
RX MAIN: 2.7 V
RX SUB: 0 V
TX: 0 V
RX: 2.0 V
TX: 0 V
SAVE ON: 3.2 V
SAVE OFF: 1.8 V
TX: 0 V
SAVE ON: 3.2 V
SAVE OFF: 1.8 V
TX: 3.2 V
RX: –3.3 V
TX: 0.2 V RX: 3.8 V
TX: 4.2 V
4.2 V
RX: 4.1 V
TX: 3.9 V
RX: 3.2 V
TX: 2.8 V
RX: 2.8 V
TX: 2.3 V
RX: 2.7 V
TX: 0 V
RX: 0 V
TX: 5.0 V
RX: –4.0 V
TX: 0 V
RX: –4.1 V
TX: –4.6 V
0.8 V
2.3 V
0 V
3.5 V
SAVE ON: 0 V
SAVE OFF: 3.5 V
SAVE ON: 3.5 V
SAVE OFF: 0.6 V
RX: 2.8 V
TX: 0 V
RX: 1.4 V
TX: 0 V
RX: 0.7 V
TX: 0 V RX: 2.8 V
TX: 0 V
5.0 V
SAVE ON: 0 V
SAVE OFF: 4.9 V
TX: 0 V
SAVE ON: 0 V
SAVE OFF: 3.2 V
TX: 0 V
RX: 4.9 V
TX: 0 V
RX: 4.8 V
TX: 0 V
RX: 0.4 V
TX: 0 V
RX: 2.9 V
TX: 0 V
0 V
RX: 3.2 V
TX: 0 V
RX: 3.9 V
TX: 0 V
RX: 1.3 V
TX: 0 V
RX: 0.7 V
TX: 0 V
RX [W]: 3.4 V
RX [N]: 0 V
TX: 0 V
RX [W]: 0 V
RX [N]: 2.9 V
TX: 0 V
0 V
RX [W]: 0.6 V
RX [N]: 0.8 V
TX [W]: 0 V
TX [N]: 0.8 V
RX [W]: 0.6 V
RX [N]: 0.8 V
TX [W]: 0 V
TX [N]: 0.8 V
RX [W]: 1.1 V
RX [N]: 0.1 V
TX: 0 V
RX [W]: 0 V
RX [N]: 1.3 V
TX: 0 V
3.5 V
1.7 V
3.5 V
RX: 2.6 V
TX: 1.6 V
SAVE ON: 0 V
SAVE OFF: 1.2 V
TX: 0 V
SAVE ON: 2.0 V
SAVE OFF: 0 V
SAVE ON: 1.5 V
SAVE OFF: 0.7 V
PLL LOCK: 3.4 V
PLL UNLOCK: 0 V
LED ON: 4.4 V
LED OFF: 4.6 V
5.0 V
7.4 V
RX: 0 V
TX: 5.0 V
RX: 0.9 V
TX: 3.4 V
5.0 V
CLOCK SHIFT ON: 1.3 V
CLOCK SHIFT OFF: 3.0 V
CLOCK SHIFT ON: 0.6 V
CLOCK SHIFT OFF: 0.7 V
CLOCK SHIFT ON: 0.8 V
CLOCK SHIFT OFF: 0.7 V
6.7 V 3.5 V
PWR ON: 7.4 V
PWR OFF: 0 V
PWR ON: 3.6 V
PWR OFF: 0 V
RX: 2.7 V
TX: 0.7 V
RX: 0 V
TX: 3.3 V
RX [W]: 0 V
RX [N]: 3.2 V
LED HI: 3.2 V
LED LOW: 0 V
LED OFF: 0 V
LED ON: 3.2 V
LED OFF: 0 V
PWR ON: 3.3 V
PWR OFF: 3.5 V
PWR ON: 3.9 V
PWR OFF: 4.1 V
PWR ON: 5.6 V
PWR OFF: 5.7 V
5.1 V
PWR ON: 3.5 V
PWR OFF: 0 V
3.5 V
7.4 V
PWR ON: 3.2 V
PWR OFF: 0 V
OPTION ON: 0 V
OPTION OFF: 3.3 V
3.5 V
3.5 V
BUSY: 0 V
MUTE: 3.2 V
TX: 3.2 V
BUSY: 3.4 V
MUTE: 0 V
TX: 0 V
BUSY: 1.4 V
MUTE: 7.4 V
TX: 7.4 V
BUSY: 7.4 V
MUTE: 0.6 V
TX: 0.6 V
3.5 V
7.4 V
7.4 V
3.5 V
3.5 V
RX: 3.1 V
TX: 3.5 V
RX: 2.7 V
TX: 0.7 V
INT: 1.9 V
EXT: 0 V
N/C MIC ON: 0 V
N/C MIC OFF: 3.3 V
N/C MIC ON: 0.7 V
N/C MIC OFF: 0 V
BUSY: 3.3 V
MUTE: 0 V
TX: 0 V
BUSY: 0.1 V
MUTE: 7.4 V
TX: 7.4 V
INT SP: 0 V
EXT SP: 2.7 V

INT SP BUSY: 0.6 V
INT SP MUTE: 0.2 V
EXT SP: 7.4 V
TX: 0.2 V



INT SP: 7.4 V
EXT BUSY: 0.6 V
EXT SP MUTE: 0.2 V
TX: 0.2 V
MUTE: 0.5 V
BUSY: 0.8 V
TX: 0.1 V
MUTE: 0.3 V
BUSY: 0.8 V
TX: 0.1 V

LED OFF: 2.8 ~ 3.3 V
LED LOW: 1.6 V
LED HI: 1.4 V

LED OFF: 2.7 ~ 3.3 V
LED LOW: 1.8 V
LED HI: 1.6 V

LED OFF: 3.5 ~ 3.3 V
LED LOW: 2.6 V
LED HI: 2.5 V







PWR OFF: 3.5 V
CLOCK SHIFT ON: 1.7 V
CLOCK SHIFT OFF: 1.9 V

PWR OFF: 3.5 V
CLOCK SHIFT ON: 1.7 V
CLOCK SHIFT OFF: 1.8 V

PWR OFF: 1.4 V
CLOCK SHIFT ON: 1.3 V
CLOCK SHIFT OFF: 3.0 V
–7.0 dBμV emf
@154.1 MHz
–9.0 dBμV emf
@154.1 MHz
0.3 dBμV emf
@154.1 MHz
–2.2 dBμV emf
0.2 V p-p
0.1 V p-p
@0.7 W
0.1 V p-p
@0.7 W
9.3 V p-p
@0.7 W

16
Main Unit
VX-920/-920E VHF series Service Manual
Note

17
Main Unit
VX-920/-920E VHF series Service Manual
Parts Layout (Lot. 1-3)
1
2
3
ABCDEFGHI
4
2SA1774 (FR)
(Q1012, 1036)
2SC4617 (BR)
(Q1066)
LC87F5BP6A
(Q1069)
DTC144EE (26)
(Q1004, 1017, 1018,
1019, 1024, 1084, 1087)
BD6111FV
(Q1028)
BR93L66RFVM
(Q1065)
LM2904PWR
(Q1076)
TDA2822D
(Q1008,1015)
DTC114TE (04)
(Q1009, 1013, 1039,
1046, 1050, 1053, 1054,
1057, 1059, 1064)
2SB1132 (BA)
(Q1003)
2SD1767 (DC)
(Q1055)
2SK3476 (BA)
(Q1010)
LA8630M
(Q1023)
M62364FP
(Q1020)
RTQ030P02
(Q1007)
TAR5S35U
(Q1062, 1063)
TAR5S50U
(Q1005)
UNR911FJ0L (6O)
(Q1026)
DA221 (K)
(D1006, 1007, 1008,
1009, 1010, 1013,
1022, 1040)
XP1501 (5R)
(Q1002)
RTM002P02 (BA)
(Q1088)
TC7S08FU (E2)
(Q1085)
NJM2130F (BA)
(Q1031)
UMD5N
(Q1086)
UMD12N
(Q1011, 1014)
LM2902PWR
(Q1075, 1077, 1083)
NJM12902V
(Q1072)
S-80835CNMC
(Q1061)
(Side A)

18
Main Unit
VX-920/-920E VHF series Service Manual
1
2
3
abcdefg
Parts Layout (Lot. 1-3)
hi
4
2SK508 (K52)
(Q1047)
2SK880GR (XG)
(Q1068)
DA221 (K)
(D1023, 1039, 1047, 1048)
2SC3356 (R24)
(Q1027)
2SC4227 (R32)
(Q1052)
2SC4617 (BR)
(Q1056, 1071)
2SC5226 (R22)
(Q1022, 1033, 1042,
1051, 1058)
AK2345
(Q1032)
DTC114TE (04)
(Q1040, 1048)
DTC144EE (26)
(Q1035, 1037, 1043,
1044, 1049, 1079, 1081)
TA31136FN
(Q1067)
2SK3478
(Q1021)
SA7025DK
(Q1070)
UNR911FJ0L (6O)
(Q1045)
UMD5N
(Q1006, 1060)
LM2904PWR
(Q1080)
CD4066BPWR (Lot.1-2)
(Q1078)
LM2902PWR
(Q1073, 1074)
NJU4066BV (Lot.3-)
(Q1078)
SPM5001
(Q1034)
DAN222 (N)
(D1020, 1044, 1046)
DAN235 (M)
(D1024, 1043)
(Side B)

19
Main Unit
VX-920/-920E VHF series Service Manual
Circuit Diagram (Lot. 4-)

20
Main Unit
VX-920/-920E VHF series Service Manual
Note