TKR-750_serv_revised2_2004.pdf

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1、 2004-10 PRINTED IN JAPAN B51-8556-20 (N) 1219 VHF FM REPEATER TKR-750 SERVICE MANUAL VHF FM REPEATER TKR-750 Front panel (A62-0934-03) Knob (DC source) (K29-9106-04) Key top (K29-5460-02) Knob (Volume) (K29-5389-03) Modular jack (E08-0877-05) Antenna cable (N) (E30-3419-05) Antenna cable (BNC) (E30

2、-3418-05) TEST/SPKR connector assy (E37-0913-05) D-sub cable assy (E37-0904-05) DC backup terminal (E70-0402-05) DC cord (Ext DC in) (E30-3414-05) Fuse (Blade, 15A/32V) (F05-1537-05) x 2 GENERAL . 2 SYSTEM SET-UP . 2 OPERATING FEATURES . 3 REALIGNMENT. 4 INSTALLATION. 5 MODIFICATION . 8 DISASSEMBLY

3、FOR REPAIR . 10 CIRCUIT DESCRIPTION. 11 SEMICONDUCTOR DATA. 18 COMPONENTS DESCRIPTION. 20 PARTS LIST. 22 EXPLODED VIEW . 34 PACKING. 36 ADJUSTMENT. 37 CONTENTS TERMINAL FUNCTION . 46 INTERCONNECTION DIAGRAM. 50 PC BOARD FINAL UNIT (X45-373X-XX) . 52 DISPLAY UNIT (X54-3330-21) . 56 TX-RX UNIT (X57-69

4、5X-XX) (A/2). 60 TX-RX UNIT (X57-695X-XX) (B/2) . 64 RX VCO UNIT (X58-4780-10) . 68 TX VCO UNIT (X58-4790-10). 69 SCHEMATIC DIAGRAM . 70 BLOCK DIAGRAM. 83 KES-5 (EXTERNAL SPEAKER). 86 SPECIFICATIONS. 87 REVISED II This service manual applies to products 60700001 or subsequent serial number. In terms

5、 of the products with the serial numbers earlier than 60700001, refer to the TKR-750 service manual as per part number B51-8556-10 and B51-8661-00. TKR-750 2 GENERAL / SYSTEM SET-UP INTRODUCTION SCOPE OF THIS MANUAL This manual is intended for use by experienced techni- cians familiar with similar t

6、ypes of commercial grade commu- nications equipment. It contains all required service informa- tion for the equipment and is current as of this publication date. Changes which may occur after publication are covered by either Service Bulletins or Manual Revisions, which are issued as required. ORDER

7、ING 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, and chassis. If the part number is not known, include the chassis or kit number of which it is a part and a sufficie

8、nt description of the required component, for proper identification. PERSONAL SAFETY The following precautions are recommended for personal safety : DO NOT transmit until all RF connectors are secure and any open connectors are properly terminated. SHUT OFF this equipment when near electrical blasti

9、ng caps or while in an explosive atmosphere. This equipment should be serviced by only qualified tech- nicians. SERVICE This radio is designed for easy servicing. Refer to the schematic diagrams, printed circuit board views, and align- ment procedures contained in this manual. Merchandise received C

10、hoose 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 4. A personal computer (IBM PC or compatible), programming interface (KPG-46), and programming software (KPG-91D) are required for programming. See p

11、age 40. The RX RF BPF (L2,L3,L5,L6,L7 on TX-RX unit A/2) must be aligned to obtain the maximum sensitivity at a programmed frequency. YES NO DC power supply or duplexer? KES-4 or KES-5 installation YES NO External speaker? Repeater programming Wide, XF1; Nar- row) to further remove spurious signals.

12、 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 ANT 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

13、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 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 circ

14、uit CIRCUIT DESCRIPTION TKR-750 12 2-3. IF Amplifier The first IF signal is amplified by Q2 and Q3, and then en- ters 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 thr

15、ough a 455kHz ceramic filter, CF1 (Wide), CF2 (Nar- row) to further eliminate unwanted signal, and the quadrature detection circuit FM-detects the signal to produce a base- band signal and output it from pin 11. 2-4. Audio Amplifier The audio amplifier circuit is located in control section of TX-RX

16、unit (X57-695 B/2). The recovered audio 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 fi

17、ltered by IC619 (A/2). The audio signal goes to an electronic volume (IC615) V3/V4, to the input of multiplexer IC (IC622), and is amplified to drive a loudspeaker by an audio power amplifier (IC629). The 4W audio output can be pro- vided to external 4 ohms speaker through the 15-pin test con- necto

18、r “SPO, SPG” on the rear panel. 2-5. Squelch 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 t

19、he analog port of the CPU (IC604). IC9 outputs 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 circuit, 3-3 driver and final power amplif

20、ier circuit, 3-4 automatic power control circuit, 3-5 RF power down detect, and 3-6 fan action control 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,

21、D502, Q501, and Q502. The AGC is operated by controlling the + and side levels of amplitude using 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 (X57-695 B/ 2) from display unit (X54-333). The transmit a

22、udio signal goes to the input of the multi- plexer IC (IC605) for microphone muting. The audio signal is amplified by IC610, input to the AINL terminal of CODEC IC (IC614), and audio processed by DSP (IC618). The processed audio signal from the AOUTL terminal of IC614 is amplified by IC616 (A/2) to

23、a sufficient level, anti-aliasing filtered by IC616 (B/2), and amplified by the summing amplifier 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 deviation ad- justment before being applied to

24、 a varactor diode in the volt- age controlled oscillator (VCO) A2 located in TX-RX unit (X57- 695 A/2). TXRX unit (X57 B/2): CONTROL MIC CODEC ICMOSW MIS TA TXO TXI MB D-SUB TD DAC SW TDS TAS AINLAOUTL SW MIC JACK J601 Display unit (X54 B/2) AMPATT DET MIC Display unit (X54 A/2) IC501(A/2)Q501,502 D

25、501,502 VR501 IC605 (A/2)IC610IC614 IC616 (B/2) IC616 (A/2) IC605 (B/2) IC615 AMPAMP IC611 (A/2) AMPLPF Fig. 2Microphone circuit CIRCUIT DESCRIPTION TKR-750 13 3-3. Driver and Final Power Amplifier Circuit The transmit signal is generated by the TX VCO (A2), am- plified by Q11, and sent to final uni

26、t (X45-373). This amplified signal is amplified by Q2, Q3, and Q4, and is passed to the FINAL stage. The RF power amplifier consists of MOS FET. TEMP Final unit (X45-373 A/2) PC POWER ADJ Vcont TX ANT ATT TCXO FCT X3 16.8MHz BUFF IC1 MB MO TX-RX unit (X57-695 A/2) CM COUPLER REF AMP DC AMP VR1 SW ST

27、T Q11 Q2 Drive AMP Q4 Drive AMP Q5 Final AMP IC1 IC1 Q8 D4D5 Q3 Drive AMP TX VCO A2 (X58-479) FWD DET REV DET PDT (to IC604 CPU) Fig. 3Driver and final power amplifier circuit 3-4. Automatic Power Control Circuit and Transmitter The automatic power control (APC) circuit stabilizes the transmitter ou

28、tput power at a pre-determined level, and con- sists of forward/reverse power detector circuits, and switch- ing transistor Q8. The forward/reverse power detector cir- cuits detects forward RF power and reverse RF power to DC voltage, and consists of a CM coupling type detection circuit formed by a

29、strip line, RF detector D4/D5, and DC amplifier IC1 (A/2). The voltage comparator (IC1 B/2) compares the above de- tected voltage with a reference voltage, set using the micro- processor and IC6 located in the TX-RX unit. An APC voltage proportional to the difference between the sensed voltage and t

30、he reference voltage appears at the output of IC1. This output voltage controls the gate voltage for the drive ampli- fier Q4 and final amplifier Q5, which keeps the transmitter output power constant. 3-5. RF Power Down Detect When the transmitter output power has dropped to or be- low the preset va

31、lues (High Power : about 20W, Low Power : about 10W) in “RF Power Down Detect” adjustment, IC604 (CPU : X57-695) detects the drop in power and outputs a Low-level (default) signal to the AUX out port. 3-6. Fan Action Control Circuit If fan action is set to “Temperature”, the cooling fan is turned ON

32、 or OFF according to temperature. If the ambient temperature of the final unit exceeds approx. 35C, the output from the temperature detection IC2 changes from H to L. This signal is sent to the CPU (IC604) by Q602 in the TX-RX unit B/2 (control section), and the out- put from pin 13 (FAS) of IC7 in

33、the TX-RX unit A/2 controlled by the CPU goes H. FAG FAB CN4 Q9 TMP FAS IC2 13 Q6 IC7 CK, DT, STB CPU IC604 TMP 17 Q602 +B X45 A/2X57 A/2X57 B/2 FAN OFF ON +20C+30C+35C +40C+50C This signal turns Q9 in the final unit ON to run the cooling fan. It has a hysteresis of approx. 2C by IC2. If fan action

34、is set to “Continuous”, the fan operates continuously, but Q9 stays ON. Fan operation Fig. 4Fan action control circuit CIRCUIT DESCRIPTION TKR-750 14 4. PLL Frequency Synthesizer The PLL frequency synthesizer circuit consists of the fol- lowing circuits : 4-1 receiver PLL circuit, 4-2 transmitter PL

35、L circuit, and 4-3 unlocked detector circuit. 4-1. Receiver PLL The receiver PLL circuit is located in VCO unit A3 (X58- 478) on TX-RX unit (X57-695 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 gen

36、erates 16.8MHz. The frequency stability is within 2.0ppm (Temperature range of 30 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 a lower h

37、eterodyne local oscilla- tor, and the VCO oscillator frequency is 180.850 to 218.850MHz. 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

38、 varactor diodes. 4-2. Transmitter PLL The transmitter PLL circuit is located in VCO unit A2 (X58- 479) on TX-RX unit (X57-695 A/2), and consists of VCXO X3, VCOs (Q350 and Q351), a single-chip PLL IC IC300, buffer amplifier Q355, and high-frequency amplifier Q302. The VCXO generates 16.8MHz. The fr

39、equency 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 through the pin 7 of the VCO. The VCO oscillator frequency is 136.000 to 17

40、4.000MHz. 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 diodes. 4-3. Unlock Detector Circuit If a pulse signal appears at the

41、 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 microprocessor de- tects this condition, the transmitter is disabled. Q351 VCO unit (X58-478) SRR VCO A IC300 VC

42、O B Q355Q350 Q354 Q352 Q353 Q300Q302 VCXO X2 TX-RX unit IC604 SW SW SW AMP AMPLPFPLL-IC -com CP,DP EPR,LDR VCO unit (X58-479) IC300Q300Q302 VCXO X3 TX-RX unit IC604 AMPLPFPLL-IC -com CP,DP EPT,LDT MOMO Q351 STT VCO A VCO B Q355Q350 Q354 Q352 Q353 SW SW SW AMP MO MO Fig. 5Receiver PLLFig. 6Transmitte

43、r PLL VCO A : 136152 VCO B : 152174 Top view TX VCO (X58-479) VCO A : 136152 VCO B : 152174 RX VCO (X58-478) (MHz) +44.850 +44.850 Fig. 7VCO oscillation frequency CIRCUIT DESCRIPTION TKR-750 15 5. Control Circuit The control circuit mainly located in the control section of TX-RX unit (X57-695 B/2) c

44、onsists of the following : 5-1 CPU, 5-2 memory circuit, 5-3 CPU clock shift, 5-4 shift register cir- cuit, 5-5 display circuit, 5-6 DSP circuit, 5-7 base-band circuit, 5-8 RS-232C circuit, 5-9 power supply circuit, and 5-10 5-tone decode circuit. 5-1. CPU The CPU (IC604) is a 16bit single-chip micro

45、computer con- taining a 32k ROM and 3k RAM. This CPU controls the flash ROM, the DSP, the receiver circuit, the transmitter circuit, the control circuit, and the display circuit and transfers data to or from an external device. 5-2. Memory Circuit IC609 has a flash ROM with a capacity of 2M bits tha

46、t contains the control program for the CPU, the signal process- ing program for DSP and data such as channels and operating features. This program can be easily written from an external de- vice. Data such as the operating status are programmed into the EEPROM (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 (X57-695). When