TTI TCB550 Service Manual

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SERVICE MANUAL

MULTI CHANNEL AM/FM TRANSCEIVER

TCB-550

TTI Tech

TABLE OF CONTENTS

SECTION 1 SPECIFICATIONS

SECTION 2 CIRCUIT DESCRIPTION

1 GENERAL

2 TECHNICAL DESCRIPTION

3 SEMICONDUCTORS AND FUNCTION

4 DESCRIPTION OF FREQUENCY DETERMINING AND STABILIZING CIRCUIT

5 TEST EQUIPMENT SETUP AND ALIGNMENT INSTRUCTIONS

SECTION

SECTION 5 BOARD LAYOUT

SECTION 6 BLOCK DIAGRAM

3 PART LIST

4 MECHANICAL DISASSEMBLY

5-1 MAIN PCB

5-2

5-3 LED PCB

5-4 VOLUME PCB

5-5 MIC PCB

FRONT PCB

SECTION 7 SCHEMATIC

SECTION1 SPECIFICATIONS

Channel Frequency Range Operating mode

G

Frequency Control

E

Frequency Tolerance

N E

Operating Temperature Range

R

Microphone

A

Input Voltage

L

Size Weight Antenna Connector

T

Power Output

R

Modulation

A N S

M

Frequency Response

I

Output Impedance

T T

Harmonic Suppression

E

Current Drain

R

40 (See the frequency band chart)

26.56 MHz ~ 28.00 MHz F3E (FM), A3E (AM) PLL Synthersizer

0.002%

-10 to + 55 C Plug-in Type

13.2V DC ± 15% 124 (W) x 135 (L) x 37 (H) 655 g Antenna Connector Duty cycle 10% 4 Watts @13.2V DC AM:from 85% to 95% FM:1.8KHz ± 0.2KHz 300Hz to 3000Hz 50ohms, Unbalanced More than -36dBm

AM Full Mod. 1.6A Max. Receiving System IF Frequencies Sensitivity

R

Dual conversion superheterodyne

Double Conversion 1st 10.695MHz/2nd 455KHz

0.7 V for 10dB(S+N)/N

in AM Mode

0.5 V for 20dB SINAD in FM Mode

E

Audio Output Power

C

Audio Distortion

E

I

Image Rejection

V

Adjacent Channel Rejection

2.0W @ 8 Ohm

Less then 8% @ 1KHz

60 dB

E

Conducted Spurious

R

Frequency Response Built-in Speaker Squelch

More than 60 dB

300 to 2500Hz

8 Ohms, round

Adjustable; Threshold less than 1 microvolt

* Specification is subject to change without prior notice.

SECTION2 CIRCUIT DESCRIPTION

------------ Contents -------------

1 General 1-1. Receiver

1.2. Transmitter

2. Technical Description 2-1. General 2-2. Type of emission 2-3. Frequency Table 2-4. RF Power Output 2-5. DC input Voltage and Current with 13.2V DC Input to Power AMP 2-6. Receiver IF and Local Oscillator Frequencies

3. Semiconductors and Function

4. Description of Frequency Determining and Stabilizing Circuit 4-1. Introduction 4-2. Basic Synthesis Scheme 4-3. Descriptions of Each Block 4-3-1. Introduction 4-3-2. Reference Frequency 4-3-3. VCO 4-3-4. Programmable Divider and its Control 4-3-5 Phase Detector and VCO Control 4-3-6. Transmitter / Receiver Buffer AMP 4-3-7. Transmitter Doublers 4-3-8. Switching of Turning Capacitor in VCO 4-3-9. Receiver Local Oscillator Outputs 4-4. Frequency Stability 4-5. Description of other Circuits 4-5-1. Transmitter 4-5-2. Receiver

5. Test Equipm 5-1. 5-2. 5-3.

6.

7.

8.

9.

10.

VCO Section Transmitter Section Receiver Section Test Data Schematic Diagram Block Diagram PCB Map PARTS LIST

ent Setup and Alignment Instructions

1. General

1-1. Receiver

Display : 40 Channels and other functions indication Frequency Range : 26.965 to 27.405 [MHz] Frequency Response : 300 to 2,500 [Hz] Power Source : 13.2 [V] DC Audio Output Load : 8 [OHM] Resistive Audio Output : 4.0 [W] (or More) Squelch : Adjustable from 0.2[uV] to 1 [mV] Sensitivity :

- FM : 20 dB [SINAD] under 1.0 [uV] or less

- AM :10 dB [S/N] under 1.0 [uV] or less

Intermediate Frequency :

- 1st IF : 10.695 [MHz]

- 2nd IF : 455 [KHz]

1-2. Transmitter

Carrier Power(Conducted) : AM 1 [W] / FM 4.0 [W] Current Drain ( 13.2 [V] Supply Voltage)

- No Modulation : 1,100 [mA] (No Modulation)

- Max Modulation : 1,400 [mA] (Full Modulation)

Modulation Capabilities

- AM : +/- 90 [%]

- FM : +/- 1.8 [KHz/Dev]

Spurious Radiation : Less then -74 [dBc] Antenna Impedance : 50 [OHM] Frequency Tolerance : 0.002 [%]

2. Technical Description

2-1. General

Model CB-550 is an mobile type AM/FM radio transceiver for use of the Citizen Radio Service.

Front Panel Controls

LCD Display(Cannel ,RX,TX,AQ,SCAN,AM,FM,EMG Indicator). Receiver Audio Control (With Power ON/OFF Control) Volume Squelch Control Volume (S/W ON : TIGHT, S/W OFF : AUTO SQ) RF Gain Control Volume

CHANNEL UP/DOWN TACT SWITCH. AM/FM TACT SWITCH

EMG TACT SWITCH

Accessable Connectors

Antenna Jack

2-2. Type of em

2-3. Frequency Range : 26.965 MHz (CH.1) - 27.405 MHz (CH.40)

External Speaker Jack External Power Cord Microphone Jack.

ission : AM(A3E) , FM(F3E)

2-4. RF Power Output : AM/FM 4.0 Watts

2-5. DC Input Voltage and Current With 13.2V DC Input to Power AMP

Transmitter Power AMP ----------- VOLTAGE 12.5 V

Current 820mA

Transmitter DRIVER AMP --------VOLTAGE 12.5 V Current 130mA

2-6. RECEIVER IF AND LOCAL OSCILLATOR FREQUENCIES.

FIRST IF -------------------------------- 10.695 MHz

SECOND IF ---------------------------- 455 KHz FIRST LOCAL OSCILLATOR------- 10.965 MHz Below RECEIVING FREQUENCY SECOND LOCAL OSCILLATOR--- 10.240 MHz

2-3. SEMICONDUCTORS AND FUNCTION

REF.NO

QR1

QR2

QR3

QR4

QR5

QR6

QR7

QQ1

QQ2

QQ4

QAS1

QAS2

QAS3

QAS4

QFS1

QFS2

QUS1

QRS1

QTS1

QG1

QG2

QG3

QG4

QG5

QHL1

QV1

QW1

QW2

QN1

QN2

QT2

QT3

QT4

Q1

Q2

Q3

IC1

IC2

IC3

IC4

IC5

IC6

IC7

DESCRIPTION RX TX REMARK

KTC4080E

KTC4075E

KTC4080E

KRA2014E

KRC410E

KTC4075E

KRC402E

KRC410E

KRA305E

KRC402E

KRC410E

KRC402E

KRC410E

KRC404E

KTC4075E

KTA2014E

KTA1658

KTA2014E

KRC401E

KTC3875S

KRC402E

KTC4080E

KRC401E

KRA305E

KTC4080

2SC2314

2SC2078

KRA226S

KRC401E

KRC404E

DBL5019

KIA358F

TDA2003

24WCO2J

TMP86FM29UG

LC7152

KIA358F

RF AMP

1'st MIXER

RF ATTENUATOR

IF AMP

A.N.L.

SQ MUTE

RF ARRENUATOR

AUTO SQ S/W

FM MUTE

AM B+

AM B+ CONTROL

X

POP MUTE

SQ CONTROL

RX B+

X

MAIN REGULATOR

CPU REGULATOR

X

VCO

X

LCD BACK LIT

CPU RESET

FM 1F

SQ CONTROL

X

EEPROM

CPU

PLL

X

RF ATTENUATOR

X

RF ATTENUATOR

X

AM AUDIO PATH

FM AUDIO S/W

X

TX B+

TX POWER REGULATOR

MAIN REGULATOR

CPU REGULATOR

POWER HI/LOW S/W

VCO

BUFFER

DOUBLER

TX ENABLE

TX ENABLE B+

BUFFER

DRIVER

POWER AMP

LCD BACK LIT

CPU RESET

X

TX AM AUDIO AMP

EEPROM

CPU

PLL

TX FM AUDIO AMP

KEC

SANYO

KEC

AUK

KEC

SGS

HOLTEK

TOSHIBA

SANYO

KEC

*** MANUFACTURER INFORMATION *** * K.E.C --------------- KOREA ELECTRONICS SEMICONDUCTOR CO.,LTD. * TOSHIBA -------------- TOSHIBA SEMICONDUCTOR CO.,LTD. * SANYO ---------------- JAPAN SANYO SEMICONDUCTOR CO.,LTD. * SGS --------------------- SGS THOMSON SEMICONDUCTOR CO.,LTD.

4. Description of Frequency Determining and Stabilizing Circuitry

4-1. Introduction

The Frequencies for transmitter and receiver first local frequencies are all derived from a signal

10.695MHz cry Phase lcoked loop.

The first local oscillator frequencies are 16.270MHz(CH1) to 16.710MHz(CH40). The second local frequency is fixed at 10.240MHz to generate second IF 455KHz. Transmit, the VCO of the PLL operates 13.4825MHz(CH1) to 13.7025MHz(40CH). The VCO frequency goes to the doublers circuit DW2, LT1, LT2 which doubles the frequency to generate 26.965MHz(CH1) to 27.405MHz(40CH).

The VCO operating frequency for the receiver is 16.27MHz(CH1) to 16.710MHz(CH40) as the first local oscillator, injected through the buffer amplifier Q302 into the first FET balanced mixer QR2,3.

4-2. Basic Synthesis Scheme

The crystal frequency(10.24MHz) is divided by 4069times to make 2.5KHz which is fed to one side of the phase detector. The VCO output is divided by a programmable divider, and fed to other side of the phase detector Pin 22, 23 of IC6.

The feedback loop is closed by passing the phase detector output through an active low pass filter and using the output to control the VCO frequency through varicap diode DV1,2.

Under locked conditions, both of phase detector input signal must be identical at 2.5KHz. The VCO frequency is then given by ;

Receiver : Fvco / N = 0.0025 [MHz] OR Fvco = 0.0025 X N [MHz]

Since “N” is an integer, the VCO frequency can be stepped up with 2.5 KHz increments.

By suitable choice of “N” the desired output frequency can be obtained.

stal and second local frequencies are derived from 10.240 MHz crystal by means of a

QV1 VCO

13.4825MHz(CH1) ~

13.7025MHz(CH40)

27.405MHz(CH40)

QW1

Doublers

26.965MHz(CH1)

To transmitter

~

Channel 1 Channel 40

N Fvco N Fvco

Transmit 5393

Receiver

See the [Table 1]for other Channels

The VCO frequency goes to the doublers circuit, with doubles the incoming signals.

VCO Output Frequency Doublers Output Frequency

3254

13.4825

16.2700

5481

3342

13.7025

16.7100

Transmit

---

Transmit

Since all frequencies are obtained from the crystal controlled PLL oscillator, all outputs are

coherent with the crystal oscillator frequency and matching the same percentage accuracy.

CH 1 , 13.4825 MHz

CH 40 , 13.7025 MHz

26.965 MHz

27.405 MHz

Program Data & Frequency[Table 1]

Channel

1 26.965 3254 16.27 2 26.975 3256 16.28 3 26.985 3258 16.29 4 27.005 3262 16.31 5 27.015 3264 16.32 6 27.025 3266 16.33 7 27.035 3268 16.34 8 27.055 3272 16.36

9 27.065 3274 16.37 10 27.075 3276 16.38 11 27.085 3278 16.39 12 27.105 3282 16.41 13 27.115 3284 16.42 14 27.125 3286 16.43 15 27.135 3288 16.44 16 27.155 3292 16.46 17 27.165 3294 16.47 18 27.175 3296 16.48 19 27.185 3298 16.49 20 27.205 3302 16.51 21 27.215 3304 16.52 22 27.225 3306 16.53 23 27.255 3312 16.56 24 27.235 3308 16.54 25 27.245 3310 16.55 26 27.265 3314 16.57 27 27.275 3316 16.58 28 27.285 3318 16.59 29 27.295 3320 16.60 30 27.305 3322 16.61 31 27.315 3324 16.62 32 27.325 3326 16.63 33 27.335 3328 16.64 34 27.345 3330 16.65 35 27.355 3332 16.66 36 27.365 3334 16.67 37 27.375 3336 16.68 38 27.385 3338 16.69 39 27.395 3340 16.70 40 27.405 3342 16.71

Frequency

[MHz]

N Fvco N Fvco

RX TX

5393 5395 5397 5401 5403 5405 5407 5411 5413 5415 5417 5421 5423 5425 5427 5431 5433 5435 5437 5441 5443 5445 5451 5447 5449 5453 5455 5457 5459 5461 5463 5465 5467 5469 5471 5473 5475 5477 5479 5481

13.4825

13.4875

13.4925

13.5025

13.5075

13.5125

13.5175

13.5275

13.5325

13.5375

13.5425

13.5525

13.5575

13.5625

13.5675

13.5775

13.5825

13.5875

13.5925

13.6025

13.6075

13.6125

13.6275

13.6175

13.6225

13.6325

13.6375

13.6425

13.6475

13.6525

13.6575

13.6625

13.6675

13.6725

13.6775

13.6825

13.6875

13.6925

13.6975

13.7025

4-3. Description Of Each Block

4-3-1. Introduction

The synthesizer is implemented with the following companents :

PLL IC (IC6) X-TAL(X2) VARICAP DIODE(DV1,2)

IC6 is a CMOS LSI that includes most of PLL block. The VCO with varicap diode DV1,2 as a part of the oscillator tank circuit. QV2 is a switching transistor to connect or disconnect the tunning capacitor in the VCO oscillator tank circuit for transmitter or receiver.

4-3-2. Reference frequency

The crystal, X2(10.24MHz) and other components at PIN 1 and 24 of IC6 can make a reference frequency oscillator with internal amplifier. The oscillator output is internally fed to a divied by 4096 to produce A 2.5KHz swuare wave witch is the reference input to the phase detector.

4-3-3. VCO

QV1 is connected as a hartley type oscillator with varicap diode as part of the tank circuit. With Appropriate control voltage on D601 the VCO can be oscillate over the required range of

13.4825MHz to 16.710 MHz.

4-3-4. Programmable divider and its control

The programmable inputs for each channel are set by the PLL clock(PIN34), DATA(PIN35), Enable(PIN33) of IC5. Each input signal to control the PLL IC is done with the provided key input PIN 12~15. For each key input, an internal code convert EEPROM provides the appropriate control to the programmable divider for that channel. Since the change transmit and receive, and additional BIT is required ar PIN 16 of IC5 to allow the ROM to recognize the status TX or RX. During transmit the push to talk switch grounds PIN 16 thru diode(DS1) which is the transmit status. Thr programmable divider output is fed to the phase detector for comparison with the 2.5KHz reference. See TABLE 1 for actual input and divide ratio on all channels.

4-3-5. Phase Detector and VCO control

The phase detector is a digital phase comparator which compares the phase of the reference woth programmable divider output square waves and develops a series of pulses whose DC level depends on the phase error of each signal. The phase detector pulse output is fed to an active low pass filter and RC LPF ouput signal of IC6 is filtered and fed to varicap DV1,2 control the VCO frequency.

4-3-6. Transmitter / Receiver Buffer AMP

The VCO output is fed into buffer AMP QW1 from the capacitor of CW1.

4-3-7. Transmitter Doubler

The output signal of QW1 goes to an amplifier tuning circuit(27MHz) QW2, LT1, LT2 which doubles incoming 13MHz signals.

4-3-8. Switching of tuning capacitor in VCO.

The VCO circuit must turn with a wide range of frequencies 13.4825MHz - 13.7025 MHz for transmitter and 16.27MHz - 16.710 MHz for receiver. The use of one tuning capacitor in common has adverse effects as a decrease in C in the tuning circuit and the occurrence of may spurious. To eliminate these effects, the tuning capacitance is switched for transmission or reception. The tank circuit consist of the primary of LV1, CV1, CV4, CV6, CV7 when receiving QV2 becomes off. So. the primary of LV1 and make tuning function. when transmitting, QW2 becomes on. So, the primary if LV1 and the parable capacitance of CV11 make turning function.

4-3-9. Receiver Local Oscillator Outputs

-First Mixer : The output of VCO is injected through buffer AMP QW1 and than The emitter follower output through the emitter of 1'st mixer or 2,3.

-Second Mixer : The output of 10.240 MHz oscillator circuit with X2 is injected into the if IC of IC1. Incoming if signal and 10.240 MHz signal are mixed inside the IF IC to 2'nd IF signal 455MHz. FM audio signal are recovered with the way of quadrature detector. AM signlas are recovered with envelope detector.

4-4. Frequency Stability

LET : Fo=Crystal Oscillator Frequency

Fr=Phase detector reference frequency Fvco=VCO frequency Ft=Transmit freqency THEN : Fr=Fo/1800 And under locked confitions : Fr =Fvco / N Where N is the programmable divider divide ratio.

THEN : Fvco= N X Fr = N(Fo/1800)

From which it can be seen, the percentage error in Ft is the percentage error in Fo. The stability of the crystal oscillator is determined primarily by the crystal itself and having lesser deviation by the active and passive components of the oscillator. The choice of crystal and components is such that the required frequency stability is maintained over the required voltage and tempertature range.

4-5. Description of other circuits.

4-5-1. Transmitter

1. RF Amplification