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24

VX-450 Series UHF Band Service Manual

Circuit Description (Version A & D)

1. Circuit Configuration by Frequency

The receiver is a Double-conversion Super-hetero-
dyne with a first intermediate frequency (IF) of 67.65
MHz and a second IF of 450 kHz. Incoming signal
from the antenna is mixed with the local signal from
the VCO/PLL to produce the first IF of 67.65 MHz.
This is then mixed with the 67.2 MHz second local
oscillator output to produce the 450 kHz 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 an-
tenna.

2. Receiver System

2-1. Front-end RF amplifier

Incoming RF signal from the antenna is delivered to
the MAIN Unit and passes through Low-pass filer,
antenna switching diode, high pass filter and re-
moved undesired frequencies by varactor diode

D1006

,

 D1007

D1009

, and

 D1010 

(tuned band-pass

filer: all 

1SV325

).

The passed signal is amplified in 

Q1007

 (

BF1212WR

)

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 332.35 and 402.35 MHz (Version “A”) or 382.35
and 452.35 MHz (Version “D”) 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

 (

2SC5226

).

The amplified first IF signal is applied to FM IF sub-
system IC 

Q1033

 (

NJM2591V

) which contains the

second mixer, second local oscillator, limiter ampli-
fier, 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

450 kHz 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 ampli-

fied 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 received, the DC voltage becomes
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 sig-

nal is output.

Summary of Contents for VX-450 series

Page 1: ...lignment 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 inconsis tencies in the technical information would be appreciated Important Note This transceiver is assembled using Pb lead free solder based on the RoH...

Page 2: ... 4 3 x 2 3 x 1 5 inches 109 x 58 5 x 37 mm VX 454 459 with FNB V133LI UNI 4 3 x 2 3 x 1 8 inches 109 x 58 5 x 45 mm VX 454 459 with FNB V134LI UNI Weight Approx 10 4 oz 296 g VX 451 with FNB V112LI Antenna Belt Clip 12 0 oz 340 g VX 451 with FNB V113LI Antenna Belt Clip 9 9 oz 281 g VX 451 with FNB V133LI UNI Antenna Belt Clip 11 6 oz 330 g VX 451 with FNB V134LI UNI Antenna Belt Clip 11 4 oz 322 ...

Page 3: ...rox 296 g VX 451 with FNB V112LI Antenna Belt Clip 340 g VX 451 with FNB V113LI Antenna Belt Clip 322 g VX 454 459 with FNB V112LI Antenna Belt Clip 366 g VX 454 459 with FNB V113LI Antenna Belt Clip 281 g VX 451 with FNB V133LI UNI Antenna Belt Clip 330 g VX 451 with FNB V134LI UNI Antenna Belt Clip 307 g VX 454 459 with FNB V133LI UNI Antenna Belt Clip 356 g VX 454 459 with FNB V134LI UNI Antenn...

Page 4: ...lable only as part of a desig nated assembly SP Connector Mating Operation 1 Insert the cable side first 2 Press down at the lever side NOTE Horizontal mating could damage the connector SP Connector Unmating Operation 1 Hook the lever 2 Pull up friction lock is released 3 Positive lock is released and removal completes Friction lock Positive lock Please remove the speaker connector from DISPLAY Un...

Page 5: ...Insert the cable side first 2 Press down at the lever side NOTE Horizontal mating could damage the connector SP Connector Unmating Operation 1 Hook the lever 2 Pull up friction lock is released 3 Positive lock is released and removal completes Friction lock Positive lock Please remove the speaker connector from DISPLAY Unit when you remove a FRONT Case of the transceiver RA1405100 O RING CAP RA140...

Page 6: ...ERSION K 16 KEY 4 KEY CP9819008 VERSION D NON KEY CP9819009 VERSION A NON KEY CP9819010 VERSION I NON KEY CP9819011 VERSION K NON KEY MIC SP CAP ASSY CB6642000 KNOB VOL RA125100B 1 KNOB FREQ RA125110B 1 HOLDER LCD RA1243200 16 KEY 4 KEY 1 LIGHT GUIDE LCD RA1243300 16 KEY 4 KEY 1 INTER CONNECTOR RA124340A 16 KEY 4 KEY 1 SPONGE RUBBER LCD RA1243500 16 KEY 4 KEY 1 REFLECTOR SHEET RA1243700 16 KEY 4 K...

Page 7: ... XTAL FILTER MFT67P 67 650MHZ H1102471 1 B d3 MAIN 2 UNIT VERSION I K CD3001 CERAMIC DISC ECDA450C24 H7901460 1 B c3 CF3001 CERAMIC FILTER LTWC450F H3900563 1 B a3 CF3002 CERAMIC FILTER LTWC450H H3900584 1 B b3 F 3001 CHIP FUSE 3 15A FHC16 322ADTP Q0000118 1 A B2 J 3008 CONNECTOR DF57H 2P 1 2V 21 P0091595 NON KEY 1 A B1 MC3001 MIC ELEMENT PF0 1055P M3290045 NON KEY 1 A C1 Q 3006 FET RQA0011DNS G0 ...

Page 8: ...8 VX 450 Series UHF Band Service Manual Block Diagram Version A D 16 key 4 key Type RF Section ...

Page 9: ...9 VX 450 Series UHF Band Service Manual Block Diagram Version A D 16 key 4 key Type Frequency Generation Reguration Section ...

Page 10: ...10 VX 450 Series UHF Band Service Manual Block Diagram Version A D 16 key 4 key Type AF Section ...

Page 11: ...11 VX 450 Series UHF Band Service Manual Block Diagram Version A D 16 key 4 key Type Controller Section ...

Page 12: ...12 VX 450 Series UHF Band Service Manual Block Diagram Version A D Non key Type RF Section ...

Page 13: ...13 VX 450 Series UHF Band Service Manual Block Diagram Version A D Non key Type Frequency Generation Reguration Section ...

Page 14: ...14 VX 450 Series UHF Band Service Manual Block Diagram Version A D Non key Type AF Section ...

Page 15: ...15 VX 450 Series UHF Band Service Manual Block Diagram Version A D Non key Type Controller Section ...

Page 16: ...16 VX 450 Series UHF Band Service Manual Block Diagram Version I K 16 key 4 key Type RF Section ...

Page 17: ...17 VX 450 Series UHF Band Service Manual Block Diagram Version I K 16 key 4 key Type Frequency Generation Reguration Section ...

Page 18: ...18 VX 450 Series UHF Band Service Manual Block Diagram Version I K 16 key 4 key Type AF Section ...

Page 19: ...19 VX 450 Series UHF Band Service Manual Block Diagram Version I K 16 key 4 key Type Controller Section ...

Page 20: ...20 VX 450 Series UHF Band Service Manual Block Diagram Version I K Non key Type RF Section ...

Page 21: ...21 VX 450 Series UHF Band Service Manual Block Diagram Version I K Non key Type Frequency Generation Reguration Section ...

Page 22: ...22 VX 450 Series UHF Band Service Manual Block Diagram Version I K Non key Type AF Section ...

Page 23: ...23 VX 450 Series UHF Band Service Manual Block Diagram Version I K Non key Type Controller Section ...

Page 24: ...ns the second mixer second local oscillator limiter ampli fier 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 remov...

Page 25: ...cy as the output of reference divider These two signals are compared by phase detector the phase difference pulse is gen erated Circuit Description Version A D 2 5 2 Carrier Squelch The CPU 14 pin A D port detect RSSI voltage out put 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 ...

Page 26: ...locked by the control of this DC voltage The PLL serial data from CPU is sent with three lines of SDO 40 pin SCK 36 pin and PSTB 30 pin The lock condition of PLL is output from the UL 18 pin terminal and UL becomes H at the time of the lock condition and becomes L at the time of the unlocked condition The CPU always watches over the UL condition and when it becomes L unlocked condition the CPU pro...

Page 27: ...econd mixer second local oscillator limiter ampli fier noise amplifier and RSSI amplifier Circuit Description Version I K The signal from reference oscillator X3001 becomes 4 times of frequencies in Q3033 it is mixed with the IF signal and becomes 450 kHz The second IF then passes through the ceramic filter CF3001 or CF3002 to strip away unwanted mixer products and is applied to the limiter amplif...

Page 28: ... detector Q3040 1 NJM12904V detects the current of Q3006 and Q3008 and converts the current difference to the voltage difference The output from the current detector Q3040 1 is com pared with the reference voltage and amplified by the power control amplifier Q3040 2 The output from Q3040 2 controls the gate bias of the final amplifiers Q3006 and the final amplifier driver Q3008 The reference volta...

Page 29: ...etector the phase difference pulse is gen erated 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 40 pin SCK 36 pin and PSTB 30 pin The lock condition of PLL is output from the UL 18 pin ...

Page 30: ...dard 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 operation of the transceiver are clearly understood the cause of the malfunction has been clearly pinpointed and any faulty components replaced and realignment determined to be ab...

Page 31: ...gnments should be made with oscillator shields and circuit boards firmly affixed in place Also the test equipment must be thoroughly warmed up before beginning Note Signal levels in dB referred to in the alignment procedure are based on 0 dBμ EMF 1 μV Test Setup Setup the test equipment as shown below for trans ceiver alignment apply 7 5 V DC power to the trans ceiver The Alignment Tool Outline In...

Page 32: ...lch SQL RSSI 5 TX Power High Low3 Low2 Low1 6 Maximum Deviation Wide Narrow Please adjust the following items when needed Modulation Balance Wide Narrow CTCSS Deviation Wide Narrow DCS Deviation Wide Narrow DTMF Alignment Seq Tone VOX ON Level TX MSK LTR Deviation Battery To enter the Alignment Mode select Alignment in the main Radio menu It will start to Upload the alignment data from the radio t...

Page 33: ...gn ment The Frequency Alignment window will appear 2 Click the PTT button or press the SPACE bar and the radio will start to transmit on the center frequency channel 3 Set the value to get the desired frequency by drag ging the slide bar clicking the up down button pressing the left or right arrow key or entering the value in the entry box 4 After getting the desired frequency click the PTT button...

Page 34: ... Up Down arrow key to switch to the se lected channel 3 Set the Signal Generator according to the indica tion at the top of the screen Setting Your SG as followings 4 Drag the slide bar click the up down buttons press the left or right arrow key or enter the value in the entry box to get the best RX sensitivity Highest RSSI value 5 Click the OK button to finish the RX Sensitivity alignment and sav...

Page 35: ...he Alignment for the level 15 of the RSSI SQL level at Wide 5k 4k or Narrow 2 5k TX Save RSSI Level TX SAVE W N The Alignment for the TX Save RSSI level at Wide 5k 4k or Narrow 2 5k The procedure for all the alignments is as follows 1 Click the Start button to open the alignment window in the SQL RSSI Alignment menu 2 The Alignment window will appear Set the Sig nal Generator according to the indi...

Page 36: ...transmit on the selected channel 4 Set the value to get desired output power High 5 W Low3 2 5 W Low2 1 W Low1 250 mW on the Power Meter by dragging the slide bar click ing the up down button pressing the left or right arrow key or entering the value in the entry box on the selected channel 5 After getting the desired output power click the PTT button or press the SPACE bar to stop transmitting 6 ...

Page 37: ...he de sired channel 5 Click the PTT button or press the SPACE bar the radio starts to transmit on the selected chan nel 6 Set the value to get desired deviation Wide 4 2kHz Narrow 2 1kHz on the deviation meter by dragging the slide bar clicking the up down button pressing the left or right arrow key or entering the value in the entry box on the selected channel 7 After getting the desired deviatio...

Page 38: ...e bar or press the Up Down arrow key to select the de sired channel 5 Click the PTT button or press the SPACE bar the radio starts to transmit on the selected chan nel 6 Set the value to get the best square wave on the Oscilloscope by dragging the slide bar clicking the up down button pressing the left or right ar row key or entering the value in the entry box on the selected channel 7 After getti...

Page 39: ...n the selected channel 4 Set the value to get desired deviation on the de viation meter by dragging the slide bar clicking the up down button pressing the left or right ar row key or entering the value in the entry box on the selected channel 5 After getting the desired deviation Wide 0 6 kHz Narrow 0 3 kHz click the PTT button or press SPACE bar to stop transmitting 6 Click the OK button to finis...

Page 40: ...on the selected channel 4 Set the value to get desired deviation Wide 0 6 kHz Narrow 0 3 kHz on the deviation meter by dragging the slide bar clicking the up down button pressing the left or right arrow key or entering the value in the entry box on the selected channel 5 After getting the desired deviation click PTT button or press SPACE bar to stop transmitting 6 Click the OK button to finish the...

Page 41: ...top trans mitting 5 Click the OK button to finish the DTMF Devia tion alignment and save the data SEQUENTIAL TONE DEVIATION This parameter is to align Sequential Tone Deviation 1 Press the Seq Tone button to start the alignment The Sequential Tone Deviation Alignment win dow will appear 2 Click the PTT button or press the SPACE bar the radio starts to transmit on the Center fre quency channel 3 Se...

Page 42: ...nment value in the New box Default 80 Input Range 0 Level Down 255 Level Up 3 Click the OK button the data will be saved and the alignment is complete TX MSK LEVEL This parameter is to align the modulation level of the ANI function 1 Press the TX MSK button to start the alignment The TX MSK Level window will appear 2 Then input the alignment value in the New box Default 9 Input Range 0 Level Down ...

Page 43: ...ick the OK button the data will be saved and the alignment is complete 4 Set the value of the DC Power source to 7 5V ac cording to the indication LTR DEVIATION This parameter is to align the LTR Deviation This parameter does not appear when adjusting the transceiver which is not installed the LTR feature 1 Press the LTR Dev button to start the alignment The LTR Deviation window will appear 2 Then...

Page 44: ...44 VX 450 Series UHF Band Service Manual MAIN Unit Circuit Diagram Version A D 16 key 4 key Type Lot 1 4 ...

Page 45: ...45 VX 450 Series UHF Band Service Manual MAIN Unit Parts Layout Version A D 16 key 4 key Type Lot 1 4 Side A 1 3 2 4 A B C D E F G ...

Page 46: ...46 VX 450 Series UHF Band Service Manual MAIN Unit Parts Layout Version A D 16 key 4 key Type Lot 1 4 Side B a b c d e f g 1 3 2 4 ...

Page 47: ...47 VX 450 Series UHF Band Service Manual MAIN Unit Circuit Diagram Version A D 16 key 4 key Type Lot 5 6 ...

Page 48: ...48 VX 450 Series UHF Band Service Manual MAIN Unit Parts Layout Version A D 16 key 4 key Type Lot 5 6 Side A 1 3 2 4 A B C D E F G ...

Page 49: ...49 VX 450 Series UHF Band Service Manual MAIN Unit Parts Layout Version A D 16 key 4 key Type Lot 5 6 Side B a b c d e f g 1 3 2 4 ...

Page 50: ...50 VX 450 Series UHF Band Service Manual MAIN Unit Circuit Diagram Version A D 16 key 4 key Type Lot 7 ...

Page 51: ...51 VX 450 Series UHF Band Service Manual MAIN Unit Parts Layout Version A D 16 key 4 key Type Lot 7 Side A 1 3 2 4 A B C D E F G ...

Page 52: ...52 VX 450 Series UHF Band Service Manual MAIN Unit Parts Layout Version A D 16 key 4 key Type Lot 7 Side B a b c d e f g 1 3 2 4 ...

Page 53: ...53 VX 450 Series UHF Band Service Manual MAIN Unit Circuit Diagram Version A D Non key Type Lot 1 7 ...

Page 54: ...54 VX 450 Series UHF Band Service Manual MAIN Unit Parts Layout Version A D Non key Type Lot 1 7 Side A 1 3 2 4 A B C D E F G ...

Page 55: ...55 VX 450 Series UHF Band Service Manual MAIN Unit Parts Layout Version A D Non key Type Lot 1 7 Side B a b c d e f g 1 3 2 4 ...

Page 56: ...56 VX 450 Series UHF Band Service Manual MAIN Unit Circuit Diagram Version A D Non key Type Lot 8 ...

Page 57: ...57 VX 450 Series UHF Band Service Manual MAIN Unit Parts Layout Version A D Non key Type Lot 8 Side A 1 3 2 4 A B C D E F G ...

Page 58: ...58 VX 450 Series UHF Band Service Manual MAIN Unit Parts Layout Version A D Non key Type Lot 8 Side B a b c d e f g 1 3 2 4 ...

Page 59: ...59 VX 450 Series UHF Band I Band Service Manual MAIN 2 Unit Circuit Diagram Version I K 16 key 4 key Type ...

Page 60: ...60 VX 450 Series UHF Band I Band Service Manual MAIN 2 Unit Parts Layout Version I K 16 key 4 key Type Side A A B C D E F G 1 3 2 4 ...

Page 61: ...61 VX 450 Series UHF Band I Band Service Manual a b MAIN 2 Unit Parts Layout Version I K 16 key 4 key Type Side B c d e f g 1 3 2 4 ...

Page 62: ...62 VX 450 Series UHF Band I Band Service Manual MAIN 2 Unit Circuit Diagram Version I K Non key Type ...

Page 63: ...63 VX 450 Series UHF Band I Band Service Manual MAIN 2 Unit Parts Layout Version I K Non key Type Side A A B C D E F G 1 3 2 4 ...

Page 64: ...64 VX 450 Series UHF Band I Band Service Manual a b Side B c d e f g 1 3 2 4 MAIN 2 Unit Parts Layout Version I K Non key Type ...

Page 65: ...65 VX 450 Series UHF Band Service Manual DISPLAY Unit Circuit Diagram 16 key 4 key Type Lot 1 4 ...

Page 66: ...66 VX 450 Series UHF Band Service Manual DISPLAY Unit Parts Layout 16 key 4 key Type Lot 1 4 Side A A B C D E 1 3 2 4 ...

Page 67: ...67 VX 450 Series UHF Band Service Manual DISPLAY Unit Parts Layout 16 key 4 key Type Lot 1 4 Side B a b c d e 1 3 2 4 ...

Page 68: ...68 VX 450 Series UHF Band Service Manual DISPLAY Unit Circuit Diagram 16 key 4 key Type Lot 5 Circuit Diagram ...

Page 69: ...69 VX 450 Series UHF Band Service Manual DISPLAY Unit Parts Layout 16 key 4 key Type Lot 5 Side A A B C D E 1 3 2 4 ...

Page 70: ...70 VX 450 Series UHF Band Service Manual DISPLAY Unit Parts Layout 16 key 4 key Type Lot 5 Side B a b c d e 1 3 2 4 ...

Page 71: ...f this manual may be reproduced without the permission of Vertex Standard LMR Inc Vertex Standard is a trademark of Vertex Standard LMR Inc All other trademarks are the property of their respective owners 2015 Vertex Standard LMR Inc All rights reserved ...

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