TKR-750_serv_2001.pdf

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1、 2001-1 PRINTED IN JAPAN B51-8556-00 (N) 1435 VHF FM REPEATER TKR-750 SERVICE MANUAL Knob (VOL) (K29-5389-03) Knob (DC source) (K29-9106-04) Key top (K29-5460-02) Panel assy (A62-0934-03) Panel (Outer) (A62-0840-03) Modular jack (E08-0543-05) GENERAL . 2 SYSTEM SET-UP . 2 OPERATING FEATURES . 3 REAL

2、IGNMENT. 11 INSTALLATION. 13 MODIFICATION. 15 DISASSEMBLY FOR REPAIR . 16 CIRCUIT DESCRIPTION . 17 SEMICONDUCTOR DATA . 23 DESCRIPTION OF COMPONENTS . 25 PARTS LIST. 27 EXPLODED VIEW. 37 PACKING . 39 ADJUSTMENT . 40 TERMINAL FUNCTION. 47 WIRING. 51 PC BOARD VIEWS RX PLL/VCO (X58-4780-10). 53 TX PLL/

3、VCO (X58-4790-10). 54 DISPLAY UNIT (X54-3330-20) . 55 FINAL UNIT (X45-3620-XX). 59 TX-RX UNIT (X57-6260-XX) (A/2). 65 TX-RX UNIT (X57-6260-XX) (B/2). 71 SCHEMATIC DIAGRAM. 77 BLOCK DIAGRAM. 89 KES-4 (EXTERNAL SPEAKER) . 92 SPECIFICATIONS. 93 CONTENTS 2 TKR-750 GENERAL / SYSTEM SET-UP INTRODUCTION SC

4、OPE OF THIS MANUAL This manual is intended for use by experienced techni- cians familiar with similar types of commercial grade com- munications equipment. It contains all required service in- formation for the equipment and is current as of the publica- tion date. Changes which may occur after publ

5、ication are covered by either Service Bulletins or Manual Revisions. These are issued as required. ORDERING REPLACEMENT PARTS When ordering replacement parts or equipment informa- tion, the full part identification number should be included. This applies to all parts : components, kits, or chassis.

6、If the part number is not known, include the chassis or kit number of which it is a part, and a sufficient description of the re- quired component for proper identification. PERSONNEL SAFETY The following precautions are recommended for person- nel safety : DO NOT transmit until all RF connectors ar

7、e verified se- cure and any open connectors are properly terminated. SHUT OFF and DO NOT operate this equipment near electrical blasting caps or in an explosive atmosphere. This equipment should be serviced by a qualified techni- cian only. SERVICE This radio is designed for easy servicing. Refer to

8、 the schematic diagrams, printed circuit board views, and align- ment procedures contained in this manual. Merchandise received Choose the type of transceiver Installation in the optional space Frequency range (MHz) TX/RX 146174 TX/RX 136150 RF power 50W 50W Type K,E K2 See page 11. A personal compu

9、ter (IBM PC or compatible), programming interface (KPG-46), and programming software (KPG-66D) are required for programming. YES NO DC power supply or duplexer? KES-4 installation YES NO External speaker? Repeater programming Wide, XF1; Nar- row) to further remove spurious signals. 2-3. IF Amplifier

10、 The first IF signal is amplified by Q2 and Q3, and then enters IC9 (FM system IC). The signal is heterodyned again with a second local oscillator signal (44.395MHz) with in IC9 to become a 455kHz second IF signal. The second IF signal is fed through a 455kHz ceramic filter, CF1 (Wide), CF2 (Nar- ro

11、w) to further eliminate unwanted signal, and the quadra- ture detection circuit FM-detects the signal to produce a base-band signal and output it from pin 11. W/N SQL DET TX-RX unit (X57 A/2): TX-RX SW SW W/NW/N MCF (Narrow) XF1 MCF (Wide) XF2 RSSI QUD W/N SW DET VCO A VCO B RX VCO A3 (X58-478) RX A

12、NT BPF L2,L3 RF AMP Q1 BPF L5,L6,L7 1st MIX DBM A1 IF AMP Q8 IF AMP Q9 LPF IF AMP Q2 44.85MHz D1 D2 IF AMP Q3 FM SYSTEM IC IC9 SWSW NOISE DET D5 NOISE AMP Q7 D3 D4 X1 44.395MHz CF1 (Wide) CF2 (Narrow) Q4 fRX+44.85MHz DEI DEO RD CODEC RA RXI RXO DAC AMP IC608 AMP IC619 (B/2) LPF IC619 (A/2) AINRAOUTR

13、 CPU IC614 IC604 IC615 SW IC622 MUTE Q606 AM SPM AF AMP INT SP IC629 RSSI ASQ TX-RX unit (X57 B/2): Control 455kHz 44.850MHz IC621 Q605INV Fig. 1Receiver circuit 18 TKR-750 2-4. Audio Amplifier The audio amplifier circuit is located in control section of TX-RX unit (X57-626 B/2). The recovered audio

14、 signal ob- tained from IC9 is amplified by IC608, input to the AINR ter- minal of CODEC IC (IC614), and audio processed by DSP (IC618). The processed audio signal from AOUTR terminal of IC614 is amplified by IC619 (B/2) to a sufficient level, anti- aliasing filtered by IC619 (A/2). The audio signal

15、 goes to an electronic volume (IC615) V3/V4, to the input of multiplexer IC (IC622), and is amplified to drive a loudspeaker by an au- dio power amplifier (IC629). The 4W audio output can be provided to external 4 ohms speaker through the 15-pin test connector “SPO, SPG” on the rear panel. 2-5. Sque

16、lch Circuit The output signal from IC9 enters FM IC again, then passed through a band-pass filter. The noise component output from IC9 is amplified by Q7 and rectified by D5 to produce a DC Voltage corresponding to the noise level. The DC voltage is sent to the analog port of the CPU (IC604). IC9 ou

17、tputs a DC voltage (RSSI) corresponding to the in- put of the IF amplifier. 3. Transmitter Circuit The transmitter circuit consists of the following circuits : 3-1 microphone circuit, 3-2 modulation level adjustment cir- cuit, 3-3 driver and final power amplifier circuit, and 3-4 auto- matic power c

18、ontrol circuit. 3-1. Microphone Circuit The signal from the microphone is passed through AGC circuit located in display unit (X54-333), so that it does not saturate. This circuit consists of IC501, D501, D502, Q501, and Q502. The AGC is operated by controlling the + and side levels of amplitude usin

19、g the current obtained by posi- tive and negative detection of the amplified audio signal. The audio signal goes to control section of TX-RX unit (X57- 626 B/2) from display unit (X54-333). The transmit audio signal goes to the input of the multi- plexer IC (IC605) for microphone muting. The audio s

20、ignal is amplified by IC610, input to the AINL terminal of CODEC IC (IC614), and audio processed by DSP (IC618). The pro- cessed audio signal from the AOUTL terminal of IC614 is amplified by IC616 (B/2) to a sufficient level, anti-aliasing fil- tered by IC616 (A/2), and amplified by the summing ampl

21、i- fier IC611 (A/2). 3-2. Modulation Level Adjustment Circuit The output of the summing amplifier IC611 (A/2) is passed to an electronic volume (IC615) for maximum devia- tion adjustment before being applied to a varactor diode in the voltage controlled oscillator (VCO) A2 located in TX-RX unit (X57

22、-626 A/2). TXRX unit (X57 B/2): CONTROL MIC CODEC ICMOSW MIS TA TXI TXO MB D-SUB TD DAC SW TDS TAS AINLAOUTL SW MIC JACK J601 Display unit (X54 B/2) AMPATT DET MI Display unit (X54 A/2) IC501(A/2)Q501,502 D501,502 VR501 IC605 (A/2)IC610IC614 IC616 (B/2) IC616 (A/2) IC605 (B/2) IC615 AMPAMP IC611 (A/

23、2) AMPLPF Fig. 2Microphone circuit CIRCUIT DESCRIPTION 19 TKR-750 3-3. Driver and Final Power Amplifier Circuit The transmit signal is generated by the TX VCO (A2), amplified by Q11, and sent to final unit (X45-362). This am- plified signal is amplified by Q2, Q3, and Q4, and is passed to the FINAL

24、stage. The RF power amplifier consists of MOS FET. TEMP Final unit (X45-362 A/2) PC POWER ADJ Vcont TX ANT ATT TCXO FCT X3 16.8MHz BUFF IC1 MB MO TX-RX unit (X57-626 A/2) CM COUPLER REF AMP DC AMP VR1 SW STT Q11 Q2 Drive AMP Q3 Drive AMP Q4 Drive AMP Q5 Final AMP IC1 IC1 Q8 D4D5 TX VCO A2 (X58-479)

25、REF DET FWD DET FAG FAB CN4 Q9 OUT 6 VTH FAS IC2 TK11050M 13 Q6 IC7 BU4094BCF CK, DT, STB CPU IC604 TEMP 17 Q602 +B X45 A/2X57 A/2X57 B/2 FAN OFF ON +20C+30C+40C+50C Fig. 3Driver and final power amplifier circuit 3-4. Automatic Power Control, Circuit and Transmitter The automatic power control (APC)

26、 circuit stabilizes the transmitter output power at a pre-determined level, and con- sists of forward/reflected power detector circuits, and switching transistor Q8. The forward/reflected power de- tector circuits detects forward RF power and reflected RF power to DC voltage, and consists of a CM co

27、upling type detection circuit formed by a strip line, RF detector D4/D5, and DC amplifier IC1 (A/2). The voltage comparator (IC1 B/2) compares the above detected voltage with a reference voltage, set using the mi- croprocessor and IC6 located in the TX-RX unit. An APC voltage proportional to the dif

28、ference between the sensed voltage and the reference voltage appears at the output of IC1. This output voltage controls the gate voltage for the drive amplifier Q4 and final amplifier Q5, which keeps the transmitter output power constant. 3-5. Fan Action Control Circuit If fan action is set to “Temp

29、erature”, the cooling fan is turned ON or OFF according to temperature. If the ambient temperature of the final unit exceeds approx. 40C, the output from pin 6 of the temperature de- tection IC2 changes from L to H. This signal is sent to the CPU (IC604) by Q602 in the TX-RX unit B/2 (control sectio

30、n), and the output from pin 13 (FAS) of IC7 in the TX-RX unit A/ 2 controlled by the CPU goes H. This signal turns Q9 in the final unit ON to run the cooling fan. It has a hysteresis of approx. 5C by IC2. If fan action is set to “Continuous”, the fan operates continuously, but Q9 stays ON. Fig. 4Fan

31、 action control circuit Fan operation CIRCUIT DESCRIPTION 20 TKR-750 4. PLL Frequency Synthesizer The PLL frequency synthesizer circuit consists of the fol- lowing circuits : 4-1 receiver PLL circuit, 4-2 transmitter PLL circuit, and 4-3 unlocked detector circuit. 4-1. Receiver PLL The receiver PLL

32、circuit is located in VCO unit A3 (X58- 478) on TX-RX unit (X57-626 A/2), and consists of VCXO X2, VCOs (Q350 and Q351), a single-chip PLL IC IC300, buffer amplifier Q355, and high-frequency amplifier Q302. The VCXO generates 16.8MHz. The frequency stability is within 2.0ppm (Temperature range of 30

33、 to +60C). The frequency tuning of the VCXO is done to apply a voltage to pin 1 of the VCXO. The output of the VCXO is applied to pin 8 of the PLL IC through the pin 7 of the VCO. The first local oscillator is an upper heterodyne local oscil- lator, and the VCO oscillator frequency is 180.850 to 218

34、.850MHz. Two VCOs cover the two bands : Q350 cov- ers the lower band and Q351 VCO covers the upper band. The oscillator frequency is controlled by applying the VCO control voltage, obtained from the phase comparator to the varactor diodes. Q351 VCO unit (X58-478) SRR VCO A IC300 VCO B Q355Q350 Q354

35、Q352 Q353 Q300Q302 VCXO X2 TX-RX unit IC604 SW SW SW AMP AMPLPFPLL-IC -com CP,DP EPR,LDR 4-2. Transmitter PLL The transmitter PLL circuit is located in VCO unit A2 (X58- 479) on TX-RX unit (X57-626 A/2), and consists of VCXO X3, VCOs (Q350 and Q351), a single-chip PLL IC IC300, buffer amplifier Q355

36、, and high-frequency amplifier Q302. The VCXO generates 16.8MHz. The frequency stability is within 2.0ppm (Temperature range of 30 to +60C). The frequency tuning and modulation of the VCXO are done to apply a voltage to pin 1 of the VCXO. The output of the VCXO is applied to pin 8 of the PLL IC thro

37、ugh the pin 15 of the VCO. The VCO oscillator frequency is 136.00 to 174.00MHz. Two VCOs cover the two bands : Q350 covers the lower band and Q351 VCO covers the upper band. The oscillator frequency is controlled by applying the VCO control voltage, obtained from the phase comparator to the varactor

38、 diodes. 4-3. Unlock Detector Circuit If a pulse signal appears at the LD pin of IC300, an unlock condition occurs, causing the voltage applied to the pin of the microprocessor to go low. The names of this pin are LDT for TX PLL and LDR for RX PLL. When the micropro- cessor detects this condition, t

39、he transmitter is disabled. Q351 VCO unit (X58-479) STT VCO A IC300 VCO B Q355Q350 Q354 Q352 Q353 Q300Q302 VCXO X3 TX-RX unit IC604 SW SW SW AMP AMPLPFPLL-IC -com CP,DP EPT,LDT MO MO MOMO Fig. 5Receiver PLLFig. 6Transmitter PLL CIRCUIT DESCRIPTION 21 TKR-750 5. Control Circuit The control circuit ma

40、inly located in the control section of TX-RX unit (X57-626 B/2) consists of the following : 5-1 CPU, 5-2 memory circuit, 5-3 CPU clock shift, 5-4 shift register circuit, 5-5 display circuit, 5-6 DSP circuit, 5-7 base-band cir- cuit, 5-8 RS-232C circuit, and 5-9 power supply circuit. 5-1. CPU The CPU

41、 (IC604) is a 16bit single-chip microcomputer containing a 32k ROM and 3k RAM. This CPU controls the flash ROM, the DSP, the receiver circuit, the transmitter cir- cuit, the control circuit, and the display circuit and transfers data to or from an external device. 5-2. Memory Circuit IC609 has a fla

42、sh ROM with a capacity of 2M bits that contains the control program for the CPU, the signal pro- cessing program for DSP and data such as channels and op- erating features. This program can be easily written from an external de- vice. Data such as the operating status are programmed into the EEPROM

43、(IC600). 5-3. CPU Clock Shift There are the 14.754MHz clock for the CPU (IC604) and the 16.515MHz clock for the DSP (IC618) at the control sec- tion of TX-RX unit (X57-626). When these clocks are multi- plexed with the reception frequency, they become an inter- nal beat signal. To prevent this, by t

44、uning Q600 and Q604 on the clock frequency is shifted. (Shift on/off can be set through programming.) 5-4. Shift Register Circuit Serial data is sent to the shift register (IC502 to IC505 located in display unit, IC602, IC623, IC7 located in TX-RX unit) from the CPU (IC604) to control various functi

45、ons in the unit. EEPROM IC600 TX-RX unit (X57 B/2): CONTROL IC601 SWQ600 X600 BEAT SHIFT Reset IC 14.754 MHz SWQ600 X601 BEAT SHIFT 16.515 MHz FLASH ROM CPU IC609 IC620 232C DRIVER IC615 D/A IC IC602/623 Shift Register IC INTERFACE ICIC603/606 DSP IC618 CODEC IC IC614 DIVIDER IC613 IC604 5-5. Displa

46、y Circuit The display circuit (X54-333) contains two 7-segment LEDs D506, D507 (orange : see the operation manual for details of display), D503 (red : transmission), D504 (green : busy), two-color LED D505 (red : backup, green : main DC), LEDs in switches S501 to S506, IC502, IC503, IC504, and IC505

47、 to display this model channels and states. IC502 to IC505 are shift registers which convert serial data from the CPU to parallel data and light LEDs. Q507, Q510, and Q511 are switching transistors which control two-color LED D505. IC506, and IC507 are three-pin power supply ICs which produce power used for the display circuit. CLK,SOE, STB1 SOSOSO KEY15 KEY LAMP 16 Display unit (X54-333-20 A/2) BUSYTXMain DC/ BACKUP Shift Reg. 1 BU4094BCFV SISISIDAT Shift Reg. 2 BU4094BCFV Shif