TTI tcb880, CB TCB880 Service Manual

SERVICE MANUAL

MULTI CHANNEL AM/FM TRANSCEIVER

TCB-880

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

Frequency Control

Frequency Tolerance

N E

Operating Temperature Range

Microphone

Input Voltage

Size Weight Antenna Connector

Power Output

Modulation

A N S

Frequency Response

Output Impedance

T T

Harmonic Suppression

Current Drain

40 (See the frequency band chart)

26.96 MHz ~ 27.99125 MHz F3E (FM), A3E (AM) PLL Synthersizer

0.002%

-10 to + 55 C Plug-in Type

13.2V DC ± 15% 156 (W) x 176 (L) x 51(H) 990 g SO-239 type Duty cycle 10% 4 Watts @13.8V 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

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

Audio Output Power

Audio Distortion

Image Rejection

Adjacent Channel Rejection

2.0W @ 8 Ohm

Less then 8% @ 1KHz

60 dB

Conducted Spurious

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 Equipment Setup and Alignment Instructions 5-1. General Section 5-2. Transmitter Section 5-3. Receiver Section

1. General

1-1. Receiver

① Display : 40 Channels and other functions indication ② Frequency Range : 26.965 to 27.405 [MHz] ③ Frequency Response : 300 to 2,500 [Hz] ④ Power Source : 13.2 [V] DC ⑤ Audio Output Load : 8 [OHM] ⑥ Audio Output : 4.0 [W] (or More) ⑦ Squelch : Adjustable from 0.3[uV] to 100 [uV] ⑧ Sensitivity :

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

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

⑨ Intermediate Frequency :

- 1st IF : 10.695 [MHz]

- 2nd IF : 455 [KHz]

1-2. Transmitter

① Carrier Power(Conducted) : AM 1 [W] / FM 4 [W] ② Current Drain ( 13.2 [V] Supply Voltage)

- No Modulation : 1,000 [mA]

- Max Modulation : 1,400 [mA]

③ Modulation Capabilities

- AM : ± 90 [%]

- FM : ± 1.8 [KHz/Dev]

④ Spurious Radiation : Less then 74 [dBc] ⑤ Antenna Impedance : 50 [OHM] ⑥ Frequency Tolerance : 0.002 [%]

2. Technical Description

2-1. General

Model CB-880 is an mobile type AM/FM radio transceiver for use of the Citizen Radio Service.

z Front Panel Controls

① LCD (Cannel and RX/TX Signal Level Indicator). ② Receiver Audio Control (With Power ON/OFF Control) Volume ③ Squelch Control Volume ④ RF Gain Control Volume ⑤ MIC GAIN Control Volume ⑥ CHANNEL UP/DOWN Rotary Switch ⑦ Q.CHANNEL UP/DOWN Rotary Switch ⑧ Memory(M1, M2, M3, M4) Key ⑨ DW(Dual Watch) Key ⑩ EMG(Emergency Channel Select) Key ⑪ AM/FM Select Key ⑫ Scan Key ⑬ CB/PA Slide Switch ⑭ ANL/OFF Slide Switch ⑮ LOCAL/DX Slide Switch

z Accessorily Connectors

① Antenna Socket ② External Speaker Jack ③ External PA Jack ④ External Signal Meter Jack ⑤ Microphone(Condenser Microphone)

2-2. Type of emission : AM(A3E) , FM(F3E)

2-3. Frequency Table

Channel Frequency (MHz) Channel Frequency (MHz)

1 26.965 21 27.215 2 26.975 22 27.225 3 26.985 23 27.235 4 27.005 24 27.245 5 27.015 25 27.255 6 27.025 26 27.265 7 27.035 27 27.275 8 27.055 28 27.285

9 27.065 29 27.295 10 27.075 30 27.305 11 27.085 31 27.315 12 27.105 32 27.325 13 27.115 33 27.335 14 27.125 34 27.345 15 27.135 35 27.355 16 27.155 36 27.365 17 27.165 37 27.375 18 27.175 38 27.385 19 27.185 39 27.395 20 27.205 40 27.405

2-4. RF Power Output

z AM : 1.0 [W] z FM : 4.0 [W]

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

z Transmitter Power Amp : Voltage 12.5 V

Current 727 mA

z Transmitter Driver Amp : Voltage 12.5 V

Current 120 mA

2-6. Receiver IF and Local Oscillator Frequencies

z First IF : 10.695 [MHz] z Second IF : 455 [KHz] z First Local Oscillator : 10.695 [MHz] Below Receiving Frequency z Second Local Oscillation : 10.240 [MHz]

3. Semiconductors and Function 3-1. Transistor

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Ref No. Description Manufacturer Function

--------------------------------------------------------------------------------------------------------------------------------------------

Q101 KTC3880S KEC RX Amplifier Q102 KTK211 KEC 1’st Mixer Q103 KTK211 KEC 1’st Mixer Q104 KRC101S KEC RX Band1 Switching Q105 KRC101S KEC RX Band2 Switching Q121 KRC110S KEC Q122 KRC112S KEC RX RSSI Level Control Q131 KTC3875S KEC Squelch Q151 KTC3875S KEC RX FM AF Amplifier Q152 KRC112S KEC FM AF Mute at AM Mode Q153 KRC101S KEC FM AF Mute at AM Mode Q154 KRC112S KEC RX AF Mute at TX Mode Q161 KTC3880S KEC AM IF Amplifier Q162 KTC3880S KEC AM IF Amplifier Q163 KRA102S KEC RX AM B+ Q164 KTA1504S KEC Automatic Noise Level Control Q181 KTC3875S KEC RX RF Mute at TX Mode Q182 KTC3875S KEC AGC Q183 KTC3875S KEC AGC Q201 KRC101S KEC AF Mute Q202 KRC202S KEC AF Path Q233 KTA1504S KEC Automatic Level Control Q234 KTC3875S KEC Automatic Level Control Q301 KTC3880S KEC VCO Q302 KTC3880S KEC RX/TX VCO Buffer Q303 KTC3880S KEC VCO Buffer Q305 KRC101S KEC TX VCO Control Q311 KRC101S KEC RX Band1 Switching Q312 KRC101S KEC RX Band2 Switching Q313 KRC101S KEC RX Band3 Switching Q502 KTC3875S KEC FM TX AF Mute at AM TX Q701 KTC3880S KEC TX Doublers Q702 KTC3880S KEC TX Pre-Amplifier Q703 KTC1006 KEC TX Driver Amplifier Q704 2SC2078 SANYO TX Power Amplifier Q742 KTC3875S KEC TX RF Mute at RX Mode Q801 KRC101S KEC CPU Reset Q802 KRC101S KEC CPU RX/TX Control Q803 KRA101S KEC MIC Lock Control Q911 KTA1658 KEC Main Regulator Q912 KRA1504S KEC Main Regulator Q913 KRC112S KEC Main Regulator Control Q914 KRC102S KEC Power Low Control Q921 KTC3875S KEC 8.2V Regulator Q922 KRC112S KEC 8.2V Regulator Mute at PA Mode Q923 KTC3875S KEC RX B+ Q924 KRA1504S KEC TX B+

Q941 KRC111S KEC Mute Q942 KRC112S KEC TX B+ Mute at TX Mode Q951 KTA1241 KEC Back Light LED Control Q952 KTA1241 KEC Back Light LED Control Q953 KRC101S KEC Back Light LED Control Q954 KRC101S KEC Back Light LED Control Q961 KRC110S KEC TX AF Mute at RX Mode Q962 KRC111S KEC MIC AF Path at AM Mode Q963 KRC111S KEC MIC AF Path at PA Mode

3-2. IC

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Ref No. Description Manufacturer Function

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IC101 TK144889V TOKO IF IC IC102 KIA358F KEC AGC, Squelch Control IC201 KIA7217AP KEC AF Power Amplifier IC301 LC7152NM SANYO PLL IC401 KIA4558F KEC FM TX AF IC801 TMP87PP21DF TOSHIBA CPU IC802 24WC02 ATMEL EEPROM

3-3. Manufacture Information

z KEC ---------------------- KEC Co., LTD. z SANYO ---------------------- SANYO Semiconductor Co., LTD. z TOKO ---------------------- TOKO, Inc. z TOSHIBA ---------------------- Toshiba Semiconductor. Co., LTD. z ATMEL ---------------------- ATMEL Co., LTD

4. Description of Frequency Determining and Stabilizing Circuit

4-1. Introduction

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

4.5MHz crystal by means of a phase locked loop(PLL). 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 Q701, L701, L702 with doubles the frequency to generate 26.965MHz(CH1) to 27.405MHz(40CH).

Q302 VCO

13.4825MHz(CH1) ~

13.7025MHz(CH40)

The VCO op erating 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 Q102, Q103.

4-2. Basic Synthesis Scheme

The crystal frequency(4.5MHz) is divided by 1800 times 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 9, 10 of IC301. Passing the phase detector output closes the feedback loop through an active low pass filter and using the output to control the VCO frequency through varicap diode D301. 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 = 0.005 [MHz] OR Fvco = 0.005 X N [MHz] Transmitter : 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 in receiver mode 5KHz and transmitter mode 2.5KHz increments. By suitable choice of “N” the desired output frequency can be obtained.

27.405MHz(CH40)

Q701

Doublers

26.965MHz(CH1)

To transmitter

Channel 1 Channel 40

N Fvco N Fvco

Transmit 5393 13.4825 5481 13.7025 Receiver 3254 16.2700 3342 16.7100

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

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 sample percentage accuracy. Note that the reference frequency of 5KHz(receiver) and 2.5KHz(transmitter) is obtained by dividing the 4.5MHz by 900 times and 1800 times See Table 1 for transmitter/receiver mode VCO frequencies.

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

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TTI tcb880, CB TCB880 Service Manual

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Frequently Asked Questions

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