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.
VX-450 Series
VHF Band
Service Manual
©2011 VERTEX STANDARD CO., LTD. EC094N90E
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
Introduction
This manual provides the technical information necessary for servicing the VX-450 Series Transceiver.
Servicing this equipment requires expertise in
handing surface-mount chip components. 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 countries.
Two PCB layout diagrams are provided for each
double-sided board in this transceiver. 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-450 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.
16 key Type
4 key Type Non-key Type
Important Note
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.
Contents
Specifications...........................................................2
Exploded View & Miscellaneous Parts.................4
16 key & 4 key Type ...........................................4
Non-key Type......................................................5
Parts List .................................................................6
Block Diagram ........................................................7
16 key & 4 key Type ...........................................7
Non-key Type....................................................11
Circuit Description ..............................................15
Alignment ..............................................................18
Board Units (Schematics & Layouts)
MAIN Unit (16 key & 4 key Type) ................. 32
MAIN Unit (Non-key Type)............................ 41
Display Unit (16 key & 4 key Type) ............... 47
1VX-450 Series VHF Band Service Manual
Specifications (USA, EXP)
General
Frequency range: 134-174 MHz
Channel / Group: 512 CH / 32 Groups (VX-459, VX-454)
32 CH / 2 Group (VX-451)
Power Supply Voltage: 7.4 V DC ± 10 %
Current Consumption: 1.7 A (5 W TX)
Channel Spacing: 12.5 / 20 / 25 kHz
PLL Steps: 12.5 / 2.5 / 5 / 6.25 kHz
Battery Life (5-5-90 duty):
2400 mAh FNB-V113LI 18.5 hours (w/saver) / 16 hours
1170 mAh FNB-V112LI 9.5 hours (w/saver) / 8.6 hours
IP Rating: IP57
Operating Temperature Range: –22 °F to +140 °F (–30 °C to +60 °C)
Charging Temperature Range: +32 °F to +113 °F (0 °C to +45 °C)
Frequency Stability: ±2.5 ppm
RF Input-Output: 50 Ohms
Dimension (H x W x D): 4.29 x 2.3 x 1.34 inches (109 x 58.5 x 34 mm) (w/FNB-V112LI)
4.29 x 2.3 x 1.69 inches (109 x 58.5 x 43 mm) (w/FNB-V113LI)
Weight (Approx.): 10.44 oz (296 g) (w/FNB-V112LI, Antenna, Belt Clip)
11.99 oz (340 g) (w/FNB-V113LI, Antenna, Belt Clip)
Receiver (Measurement per TIA/EIA-603)
Circuit Type: Double Conversion Super-heterodyne
Sensitivity (12dB SINAD): 0.25 μV
Adjacent Channel Selectivity: 70/65 dB (W/N)
Hum and Noise: 45/40 dB (W/N)
Intermodulation: 70/65 dB (W/N)
Spurious Image Rejection: 70 dB
Audio output: 700 mW (intemal @ 16 Ohms 5% THD)
500 mW (extemal @ 4 Ohms 5% THD)
Transmitter (Measurement per TIA/EIA-603)
Output Power: 5 / 2.5 / 1 / 0.25 W
Modulation: 16K0F3E/11K0F3E)
Maximum Deviation: ±5.0 kHz / ±2.5 kHz
Conducted Spurious Emissions: 70 dB below carrier
FM Hum & Noise: 45 dB / 40 dB
Audio Distortion: < 3% @ 1kHz
Specifications subject to change without notice or obligation.
2VX-450 Series VHF Band Service Manual
Specifications (EU)
General
Frequency range: 134-174 MHz
Channel / Group: 512 CH / 32 Groups (VX-459, VX-454)
32 CH / 2 Group (VX-451)
Power Supply Voltage: 7.4 V DC ± 10 %
Current Consumption: 1.7 A (5 W TX)
Channel Spacing: 12.5 / 20 / 25 kHz
PLL Steps: 12.5 / 2.5 / 5 / 6.25 kHz
Battery Life (5-5-90 duty):
2400 mAh FNB-V113LI 18.5 hours (w/saver) / 16 hours
1170 mAh FNB-V112LI 9.5 hours (w/saver) / 8.6 hours
IP Rating: IP57
Operating Temperature Range: –20 °C to +55 °C
Charging Temperature Range: +5 °C to +35 °C
Frequency Stability: ±2.5 ppm
RF Input-Output: 50 Ohms
Dimension (H x W x D): 4.29 x 2.3 x 1.34 inches (109 x 58.5 x 34 mm) (w/FNB-V112LI)
4.29 x 2.3 x 1.69 inches (109 x 58.5 x 43 mm) (w/FNB-V113LI)
Weight (Approx.): 10.44 oz (296 g) (w/FNB-V112LI, Antenna, Belt Clip)
11.99 oz (340 g) (w/FNB-V113LI, Antenna, Belt Clip)
Receiver (Measurement per EN300 086)
Circuit Type: Double Conversion Super-heterodyne
Sensitivity (20 dB SINAD): –4 dBμV / –2 dBμV (W/N)
Adjacent Channel Selectivity: 70/65 dB (W/N)
Hum and Noise: 45/40 dB (W/N)
Intermodulation: 70/65 dB (W/N)
Spurious Image Rejection: 70 dB
Audio output: 700 mW (intemal @ 16 Ohms 5% THD)
500 mW (extemal @ 4 Ohms 5% THD)
Transmitter (Measurement per EN300 086)
Output Power: 5 / 2.5 / 1 / 0.25 W
Modulation: 16K0F3E/11K0F3E)
Maximum Deviation: ±5.0 kHz / ±2.5 kHz
Spurious Emissions: –36 dBm (< 1 GHz), –30 dBm (> 1 GHz)
FM Hum & Noise: 45 dB / 40 dB
Audio Distortion: < 3% @ 1kHz
Specifications subject to change without notice or obligation.
3VX-450 Series VHF Band Service Manual
Exploded View & Miscellaneous Parts (16 key & 4 key Type)
RA1252100
CAP (MIC/SP)
RA1250900
BUSH (2 pcs)
RA1251000
KNOB (VOL)
RA1251100
KNOB (FREQ)
RA1243200
HOLDER(LCD)
G6090208
LCD
RA1243400
INTER CONNECTOR
RA1243300
LIGHT GUIDE (LCD)
RA1243700
REFLECTOR SHEET
RA1250800
RING NUT
RA1277900
LEAF SPRING (TOP-SEL)
RA1250800
RING NUT
RA1250900
BUSH (2 pcs)
CP9788001
FRONT CASE ASSY(16KEY)
CP9788002
FRONT CASE ASSY(4KEY)
WINDOW, DOUBLE FACE TAPE, SPONGE RUBBER (LCD),
LIGHT GUIDE, O RING, RUBBER (TOP-SEL), RUBBER (SIDE),
RUBBER (PTT), FRAME (PTT), KEY PAD (4KEY),
LATCH PLATE, COIL SPRING (2 pcs),
ESCUTCHEON (DOT), DOUBLE FACE TAPE (ESC), SP NET,
SPEAKER, PLATE, WIRE ASSY,
BIND HEAD TAPTITE-B M2X5 (2 pcs)
RA1246600
RUBBER BOOTS(MIC)
RA0323800
SHEET
M3290032
MIC. ELEMENT
P0091542
SP-CONNECTOR
Please remove the speaker
connector from DISPLAY Unit
when you remove a FRONT Case
of the transceiver.
SP-Connector Unmating Operation
DISPLAY UNIT
MAIN UNIT
RA1314300
BLIND SHEET
RA1247400
PAD(PWB)
1. Hook the lever.
2. Pull up friction lock is released.
RA1316200
RUBBER BOOTS (CONT)
RA037690B
SHEET (6X6)
CP9787001
CHASSIS (W/ CONNECTOR)
RA1313900
PACKING PAD
RA1247800
INSULATOR
RA124760A
LID
RA0292100
SHEET (M TEX(010))
VXSTD P/N
AAH12X101
AAH07X001
AAH08X001
AAH73X002
AAH73X003
AAH73X004
Ref.
VXSTD P/N
U24110001
U44105001
U32230001
U20206007
Optional Accessories
Belte Clip CLIP-20
Li-Ion BATTERY PACK FNB-V112LI
Li-Ion BATTERY PACK FNB-V113LI
Antenna ATV-16A (136 MHz~149 MHz)
Antenna ATV-16B (158 MHz~161 MHz)
Antenna ATV-16C (162 MHz~174 MHz)
Description
BIND HEAD TAPTITE-B
PAN HEAD TAPTITE-B
PAN HEAD SCREW
BINDING HEAD SCREW
Description
M2X10N
M2X5NI
M2X3(3)
M2.6X6B
RA1278400
CAUTION LABEL
Qty.
6
6
2
2
Non-designated parts are available only as part of a designated assembly.
RA124730A
O RING
3. Positive lock is released and
removal completes.
SP-Connector Mating Operation
1.Insert the cable side first.
Li-Ion BATTERY PACK
FNB-V112LI or FNB-V113LI
Belte Clip
CLIP-20
2.Press down at the lever side.
Positive lock
Friction lock
NOTE: Horizontal mating could
damage the connector.
4VX-450 Series VHF Band Service Manual
Exploded View & Miscellaneous Parts (Non-key Type)
RA1252100
CAP (MIC/SP)
RA1250800
RING NUT (2pcs)
RA1250900
BUSH (2pcs)
RA1251000
KNOB (VOL)
RA1251200
WASHER (FREQ)
RA1251100
KNOB (FREQ)
M3290045
MIC. ELEMENT
RA1331600
MYLAR SHEET (MIC) (2pcs)
RA1331800
BLIND SHEET (SP_WIRE)
P0091542
SP-CONNECTOR
CP9813001
FRONT CASE ASSY
LIGHT GUIDE, RUBBER (TOP-SEL), LATCH PLATE,
SP NET, NAME PLATE, FRAME (PTT), COIL SPRING,
ESCUTCHEON (16CH), PLATE (FREQ),RUBBER (SIDE),
DOUBLE FACE TAPE (ESC), FRONT CASE (NON-KEY),
SHEET (M-TEX9_4.5), RUBBER (PTT), PORON SHEET (50X6),
BLIND SHEET (SP_WIRE), PLATE, SPEAKER (16OHM-1W),
WIRE ASSY (65MM2P2F), BIND HEAD TAPTITE-B M2X5 (2 pcs)
RA011020A
HOLDER RUBBER(MIC)
MAIN Unit
RA1332100
SPACER
Please remove the speaker
connector from DISPLAY Unit
when you remove a FRONT Case
of the transceiver.
RA1277900
LEAF SPRING (TOP-SEL)
RA1316200
RUBBER BOOTS (CONT)
RA037690B
SHEET (6X6)
CP9812001
CHASSIS ASSY (W/ CONNECTOR)
RA1313900
PACKING PAD (OPTION)
RA1247800
INSULATOR (OPTN)
RA124760A
LID (OPTION)
RA0292100
SHEET (MICROTEX C010)
RA1278400
CAUTION LABEL
RA124730A
O RING (CHASSIS)
SP-Connector Unmating Operation
1. Hook the lever.
2. Pull up friction lock is released.
3. Positive lock is released and
removal completes.
SP-Connector Mating Operation
1.Insert the cable side first.
Ref.
VXSTD P/N
U24110001
U44105001
U32230001
U20206007
U44110002
BIND HEAD TAPTITE-B
PAN HEAD TAPTITE-B
FLAT HEAD SCREW
BINDING HEAD SCREW
PAN HEAD TAPTITE-B
Description
M2X10N
M2X5NI
M2X3(3)
M2.6X6B
M2X10NI
Qty.
2
9
2
2
1
Non-designated parts are available only as part of a designated assembly.
Li-Ion BATTERY PACK
FNB-V112LI or FNB-V113LI
Belte Clip
CLIP-20
VXSTD P/N
AAH12X101
AAH07X001
AAH08X001
Q3000243
Q3000244
Q3000245
2.Press down at the lever side.
Friction lock
NOTE: Horizontal mating could
damage the connector.
Optional Accessories
Belte Clip CLIP-20
Li-Ion BATTERY PACK FNB-V112LI
Li-Ion BATTERY PACK FNB-V113LI
Antenna ATV-16A (136 MHz~149 MHz)
Antenna ATV-16B (158 MHz~161 MHz)
Antenna ATV-16C (162 MHz~174 MHz)
Description
Positive lock
5VX-450 Series VHF Band Service Manual
Parts List
DESCRIPTION VALUE V/W TOL. VXSTD P/NMFR’S DESIG VERS.REF. LOT. SIDE
MAIN PCB with Components CS2095701 16 KEY
MAIN PCB with Components CS2095702 4 KEY
MAIN PCB with Components CS2097701 NON-KEY
DISPLAY PCB with Components CB5471001
MAIN Unit Printed Circuit Board FR021580G
MAIN Unit Printed Circuit Board FR021670D NON-KEY
DISPLAY Unit Printed Circuit Board FR021560E
FRONT CASE ASSY (16KEY) CP9788001 16 KEY 1FRONT CASE ASSY (4KEY) CP9788002 4 KEY 1FRONT CASE ASSY (NON-KEY) CP9813001 NON-KEY 1KNOB (VOL) RA1251000 1KNOB (FREQ) RA1251100 1SPEAKER AC094U 36MM16OHM1W M4090204 1HOLDER (LCD) RA1243200
LIGHT GUIDE (LCD) RA1243300
INTER CONNECTOR RA1243400
SPONGE RUBBER (LCD) RA1243500
REFLECTOR SHEET RA1243700
CAP (MIC/SP) RA1252100 1BINDING HEAD SCREW 2 pcs M2.6X6B U20206007 1BIND HEAD TAPTITE-B 6 pcs 2X10N U24110001
BIND HEAD TAPTITE-B 2 pcs 2X10N U24110001 NON-KEY 1BIND HEAD TAPTITE-B 2 pcs M2X5 (SPEAKER) U24105001 1PAN HEAD TAPTITE-B 6 pcs M2X5 U44105001
PAN HEAD TAPTITE-B 9 pcs M2X5 U44105001 NON-KEY 1FLAT HEAD SCREW M2X3(3) U32230001 1-
PAN HEAD TAPTITE-B M2X10NI U44110002 NON-KEY 1F 1001 CHIP FUSE 3.15A FHC16 322ADTP Q0000118 1- A B1
Q 1006 FET RQA0011DNS G3070392 1- A B2
S 1001 TACT SWITCH EVQPUB02K N5090167 1- B c1
S 1002 TACT SWITCH EVQPUB02K N5090167 1- B c2
S 1003 TACT SWITCH EVQPUB02K N5090167 1- B c3
S 1004 TACT SWITCH EVQPUB02K N5090167 1- A A1
S 1005 ROTARY SWITCH
SC1001 SHIELD CASE (VCO) RA1250300 1- B a3
TH1001 THERMISTOR TH05 4B473FR G9090150 1- A A5
VR1001 POT.
X 1001 TCXO 16.8MHz TTS14VSB-A3 16.80MHZ H9501100 1- B b4
X 1002 XTAL 32.768kHz 4809995L18 32.768KHZ H0103407 1- A B4
XF1001 XTAL FILTER 1D50811GQ2 50.85M H1102462 1- B c3
DS2001 LCD GS-35719-TFZWH G6090208
J 2002 CONNECTOR DF57-2P-1.2V(21) P0091542
J 1008 CONNECTOR DF57-2P-1.2V(21) P0091542 NON-KEY 1- A C2
MC2001 MIC. ELEMENT EM-140 M3290032
MC1001 MIC. ELEMENT PF0-1055P M3290045 NON-KEY 1- A C3
TP70GF4161 14.7F RY-10031
TP76N975N13.5FB503RY10034 J60800314
N0190196 1- B b1
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
16 KEY & 4 KEY
11111-
1-
1-
1- B a1
1- A B1
1- A A4
1- A C4
LAY ADR
6VX-450 Series VHF Band Service Manual
Block Diagram (16 key & 4 key Type)
7VX-450 Series VHF Band Service Manual
Block Diagram (16 key & 4 key Type)
8VX-450 Series VHF Band Service Manual
Block Diagram (16 key & 4 key Type)
9VX-450 Series VHF Band Service Manual
Block Diagram (16 key & 4 key Type)
10VX-450 Series VHF Band Service Manual
Block Diagram (Non-key Type)
11VX-450 Series VHF Band Service Manual
Block Diagram (Non-key Type)
12VX-450 Series VHF Band Service Manual
Block Diagram (Non-key Type)
13VX-450 Series VHF Band Service Manual
Block Diagram (Non-key Type)
14VX-450 Series VHF Band Service Manual
Circuit Description
1. Circuit Configuration by Frequency
The receiver is a Double-conversion Super-heterodyne with a first intermediate frequency (IF) of
50.85MHz and a second IF of 450KHz. Incoming signal from the antenna is mixed with the local signal
from the VCO/PLL to produce the first IF of 50.85
MHz.
This is then mixed with the 50.4 MHz second local
oscillator output to produce the 450kHz second IF.
This is detected to give the demodulated 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 signal from the antenna is delivered to
the RF Unit and passes through Low-pass filer, antenna switching diode, high pass filter and removed
undesired frequencies by varactor diode D1006,
D1007 and D1009, D1010 (tuned band-pass filer).
The passed signal is amplified in Q1007 (2SK293)
and moreover cuts an image frequency with the
tuned band pass filter and comes into the 1st mixer.
2-2. First Mixer
The 1st mixer consists of the Q1015 (3SK293). Buff-
ered output from the VCO is amplified by Q1014
(2SC5005) to provide a pure first local signal be-
tween 184.85 and 224.85 MHz for injection to the first
mixer.
The IF signal then passes through monolithic crystal
filters XF1001 (± 7.5 kHz BW) to strip away all but
the desired signal.
2-3. IF Amplifier
The first IF signal is amplified by Q1025 (2SC5526).
The amplified first IF signal is applied to FM IF sub-
system IC Q1033 (NJM2591V) which contains the
second mixer, second local oscillator, limiter amplifier, noise amplifier, and RSSI amplifier.
The signal from reference oscillator X1001 becomes
4 times of frequencies in Q1033, it is mixed with the
IF signal and becomes 450 kHz.
The second IF then passes through the ceramic filter
CF1001 or CF1002 to strip away unwanted mixer
products, and is applied to the limiter amplifier in
Q1033, which removes amplitude variations in the
450kHz IF, before detection of the speech by the ce-
ramic discriminator CD1001 (ECDA450C24).
2-4. Audio amplifier
Detected signal from Q1033 (NJM2591V) is input-
ted to Audio Processor IC Q1013.
The signal which appeared from Q1001 is in high
pass filter Q1041 (NJM12902V).
The signal which passed Q1041 goes to AF volume
(VR1001). And then the signal goes to audio ampli-
fier Q1048 (TDA2822L-50B).The output signal from
J1006 is in audio speaker.
2-5. Squelch Circuit
There are 16 levels of squelch setting from 0 to 15.
The level 0 means open the squelch. The level 1
means the threshold setting level and level 14 means
tight squelch. From 2 to 13 is established in the
middle of threshold and tight.
The bigger figure is nearer the tight setting. The level
15 becomes setting of carrier squelch.
2-5-1. Noise Squelch
Noise squelch circuit is composed of the band path
filter and noise detector of Q1033.
When a carrier isn't received, the noise ingredient
which goes out of the demodulator Q1033 is amplified in Q1037 through the band path filter, is detected
to DC voltage with D1031 and is inputted to 15 pin
(the A/D port) of the Q1035 (CPU).
When a carrier is receiv
low because the noise is compressed.
When the detected voltage to CPU is high, the CPU
stops AF output with Q1049 "OFF" by making the 90
pin (CPU) "L" level.
When the detection voltage is low, the CPU makes
Q1049 ON with making 90 pin "H" and the AF signal is output.
2-5-2. Carrier Squelch
The CPU (14pin: A/D port) detect RSSI voltage output from Q1033 12 pin, and controls AF output.
The RSSI output voltage changes according to the
signal strength of carrier. The stronger signal makes
the RSSI voltage to be higher voltage.
ed, the DC voltage becomes
15VX-450 Series VHF Band Service Manual
Circuit Description
The process of the AF signal control is same as Noise
Squelch.
The shipping data is adjusted -1dBu (EMF) higher
than squelch tight sensitivity.
3. Transmitter System
3-1. MIC Amplifier
The AF signal from internal microphone MC2001 or
external microphone J1004 in to Audio processor IC
Q1013. (selected 34pin or 35pin) Q1013 is which contains the microphone amplifier, compandor, Preemphasis, limiter and splatter filter, the processed
signal to made FM modulation to transmit carrier
by the modulator D1014 (HVC383B) of VCO.
Q1013 is DTMF Receiver, and Inversion Type Encryption.
3-2. Drive and Final Amplifier Stages
The modulated signal from the VCO Q1023
(2SC4227) is buffered by Q1017 (2SC5005) . Then
the signal is buffered by Q1010 (2SC3356) for the
final amplifier driver Q1015 (RQA0004PXDQS). The
low-level transmit signal is then applied to Q1006
(RQA0011DNS) for final amplification up to 5watts
output power.
The transmit signal then passes through the antenna
switch D1005 (HVU131) and is low pass filtered to
suppress away harmonic spurious radiation before
delivery to the antenna.
3-3. Automatic Transmit Power Control
The current detector Q1040-1 (NJM12904V) detects
the current of Q1006 and Q1008, and converts the
current difference to the voltage difference.
The output from the current detector Q1040-1 is com-
pared with the reference voltage and amplified by
the power control amplifier Q1040-2.
The output from Q1040-2 controls the gate bias of
the final amplifiers Q1006 and the final amplifier
driver Q1008.
The reference voltage changes into four values
(Transmit Power High and Low) controlled by Q1040
(NJM12904V).
3-4. PLL Frequency Synthesizer
The frequency synthesizer consists of PLL IC, Q1036
(AK1541), VCO, TCXO (X1001).
The output frequency from TCXO is 16.8 MHz and
the tolerance is +/- 2.5 ppm (in the temperature range
-30 to +60 degrees).
3-4-1. VCO (TX Voltage-Controlled Oscillator)
While the radio is receiving, the RX oscillator Q1019
(2SK508) in VCO generates a programmed fre-
quency between 201.65 and 241.65MHz as 1st local
signal.
While the radio is transmitting, the TX oscillator
Q1023 (2SC4227) in VCO generates a frequency be-
tween 134 and 174 MHz.
The output from oscillator is amplified by buffer
amplifier Q1017 (2SC5005) and becomes output of
VCO. The output from VCO is divided, one is amplified by Q1022 and feed back to the PLL IC 17 pin.
The other is amplified in Q1014 and in case of the
reception, it is put into the mixer as the 1st local signal through D1011, in transmission, it is buffered
Q1010, and more amplified in Q1008 and it is put
into the final amplifier Q1008.
3-4-2. VCV (Varactor Control Voltage) Control
Tuning voltage of VCO is expanding the lock range
of VCO by controlling the cathode of varactor diode
at the voltage and the control voltage from PLL IC.
3-4-3. PLL
The PLL IC consists of reference divider, main divider, phase detector, charge pumps and pulse swallow operation. The reference frequency from TCXO
is inputted to 10 pin of PLL IC and is divided by
reference divider.
The other hand, inputted feed back signal to 17 pin
of PLL IC from VCO is divided with the dividing
ratio which becomes same frequency as the output
of reference divider. These two signals are compared
by phase detector, the phase difference pulse is generated.
The phase difference pulse and the pulse from
through the charge pumps and LPF. It becomes the
DC voltage to control the VCO.
The oscillation frequency of VCO is locked by the
control of this DC voltage.
The PLL serial data from CPU is sent with three lines
of SDO (40pin), SCK (36pin) and PSTB (30pin).
The lock condition of PLL is output from the UL
16VX-450 Series VHF Band Service Manual
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