Kenwood_TH-F6_TH-F7_serv_YO3HJV.pdf

《Kenwood_TH-F6_TH-F7_serv_YO3HJV.pdf》由会员分享，可在线阅读，更多相关《Kenwood_TH-F6_TH-F7_serv_YO3HJV.pdf（74页珍藏版）》请在收音机爱好者资料库上搜索。

1、144/220/440MHz FM TRIBANDER / 144/430MHz FM DUAL BANDER TH-F6A/F7E 2001-8 PRINTED IN JAPAN B51-8580-00 (S) 798 SERVICE MANUAL DISASSEMBLY FOR REPAIR. 2 CIRCUIT DESCRIPTION . 4 DESCRIPTION OF COMPONENTS. 14 PARTS LIST. 19 EXPLODED VIEW . 32 PACKING . 33 ADJUSTMENT . 34 PC BOARD VIEWS TX-RX UNIT (CONT

2、ROL SECTION) . 59 TX-RX UNIT . 65 TX-RX UNIT (VCO SECTION). 71 SCHEMATIC DIAGRAM . 73 BLOCK DIAGRAM . 81 LEVEL DIAGRAM . 83 OPTIONS . 85 SPECIFICATIONS . 86 CONTENTS KNOB(ENC) (K29-5159-03) WHIP ANTENNA (T90-0781-05):K (T90-0789-05):T,E KNOB(VOL) (K29-5150-03) CABINET ASSY (A02-3620-13):T,E (A02-371

3、9-13):K CAP (B09-0615-23) FRONT GLASS (B10-2685-13):T,E (B10-2723-13):K KEY TOP (K29-9107-12) KNOB(PTT/MONI) (K29-9108-13) TH-F6A/F7E 2 DISASSEMBLY FOR REPAIR 1. How to remove the case assembly from the chassis: 1. Remove 2 screws (1). 2. Remove 2 knobs (2) and 2 round nuts (3). 3. Remove the SP/MIC

4、 jack cover (4). 4. Open the bottom part of case assembly and lift the front panel from the chassis (5). 2. How to remove the main PCB: 2-1. Control section 1. Remove the SP/MIC jack cover (6). 2. Remove 5 screws (7) and lift and remove the control PCB (TX-RX A/3). 3. Extract the encoder flat cable

5、from the connector. 2-2. RF section 4. Remove 8 screws (8), and 1 round screw (9), then remove the RF shield cover. Remove the soldering that connects the whip antenna and bar-antenna (3 locations). 5. Remove the battery terminal screw (0). 6. Lift and remove the RF PCB (TX-RX B/3). 2-3. PLL/VCO sec

6、tion 7. Remove the soldering (8 locations) that holds the PLL/VCO shield cover (!) then lift the shield cover. 8. Lift the PLL/VCO PCB upward to seperate it from the main PCB. 3 3 1 2 2 4 6 7 7 7 8 8 8 8 8 8 9 10 5 11 Fig. 1 TH-F6A/F7E 3 DISASSEMBLY FOR REPAIR 3. Soldering the Bar antenna wires Befo

7、re solding the bar antenna wires, form the wires as shown in the figure 2. Then solder the wires to lands on the PCB. Fig. 2 4. Removing a relay terminal Insert a screw driver between the relay terminal and its holder. Then pull the relay terminal as shown in the figure 3. 5. Assembling a release la

8、tch Place a coil spring(1) on the release latch(2) as shown in the figure 4. Then insert a shaft(3) into the release latch. Push the above assembly into the rear panel while the end of coil spring is hooked to the “A” tab. Fig. 4 2 1 3 NotchNotch A 6. Caution at the time of reassembling While you ar

9、e reassembling the battery terminal holder (J19-5428) and the packing (G53-1532), confirm that the packing is reassembled at the condition that any swell is not occurred on it. If the packing is assembled with any swell, width of body also becomes expansive. J19-5428 G53-1532 Swell not allowed Fig.

10、3 Fig. 5 TH-F6A/F7E 4 CIRCUIT DESCRIPTION 1. A band receiver system 1-1. Receiver circuit The A band can receive signals in two bands: VHF (220 MHz band ) and UHF (K type: three bands). It uses FM receive mode only, and uses double conversion with the first IF of 59.85 MHz and the second IF of 450 k

11、Hz. The first amplifier is divided into two bands: 137 MHz - 173.995 MHz (216 MHz - 260 MHz ) and 410 MHz - 470 MHz. The incoming signal from the antenna passes through a low-pass filter and a duplexer, and goes to an independent amplifier (Q63, Q62) for each band. 1-1-1. VHF band frontend The incom

12、ing signal from the antenna passes through a VHF band low-pass filter and a duplexer, passes through a band-pass filter where it is tuned with varicaps (D76, D77), and goes to the first amplifier (Q63). Unwanted signal components are eliminated by a two-pole band-pass filter where it is tuned by var

13、icaps (D72, D75, D81, D83), and the signal goes to the common mixer (Q45) for the A band. (K type only: For 200MHz band reception, D74 is turned off with a control signal to improve band-pass filter coupling and ensure pass bandwidth.) ANT Q45 MT6C 04AE BPF APC&VTUNEA MIX Q63 3SK320 RFAMPBPFBPF MPU

14、D76 D77 D72,D75 D81,D83 LPF LO 1st IF 59.85MHz Fig.1 1-1-2. UHF band frontend The incoming signal from the antenna passes through a UHF band low-pass filter and enters the first amplifier (Q62) common to both A and B bands. The amplified signal is distributed by L distributors (L95, L96) and goes to

15、 the LC filter module (L92). Unwanted signal components are eliminated by the filter, and the resulting signal passes through another band-pass filter and enters the mixer (Q45). ANT BPF Q62 3SK320 RFAMP L95 L96 HPFLPF L92 Q45 MT6C 04AE MIX LO 1st IF 59.85MHz BPF LC FILTER MODULE 1-1-3. Circuits fol

16、lowing IF The signal heterodowned to the first IF of 59.85 MHz by the mixer (Q45) passes through a 15kHz MCF (XF2) and unwanted signal components are eliminated. The resulting signal is amplified by the IF amplifier (Q43) and goes to the FM IC (IC7). The FM IC heterodowns it to the second IF of 450

17、kHz. Then, the signal passes through a 15kHz external ceramic filter (CF4) and goes to the FM IC again. The signal amplified by the IF amplifier built into the IC is demodulated by the quadrature FM demodulation circuit using a discriminator (CD1) and converted into an audio signal and output. The F

18、M modulation signal output from the FM IC passes through a low-pass filter consisting of a resistor and a capacitor and is output to the control section. The demodulation signal input to the control section goes to the electronic volume (IC706, pin 13) to adjust the audio balance with the B band. Th

19、e output signal is amplified by the operational amplifier (IC717), passes through an active filter consisting of Q719 and Q717, and goes to the audio amplifier (IC707). The signal amplified to a higher power by the audio amplifier becomes the final output signal from the set and output through the i

20、nternal speaker or speaker output pin (J701). Q45 MT6C 04AE MIX LO X3 IC7 XF2 X1 TCXO Q44 2SC 4915 IFAMPMCF Q43 2SC 5108(Y) 19.8MHZ CF4 4.50KHz LPF IC700 VR BAF IC707 Q719 Q717 AUDIO AMPDE EMPHASIS IC717 AMP SP J701 Fig.3 Fig.2 1-2. Mixer local oscillator 1-2-1. First mixer The local oscillator sign

21、al for the first mixer is supplied from the VCO-PLL circuit. 1-2-2. Second mixer The local oscillator signal for the second mixer is a 59.4 MHz signal that is produced by multiplying the 19.8MHz TCXO (X1) oscillator output with a multiplier (Q44). 2. B band receiver system 2-1. Receiver circuit The

22、B band has a broadband receiver circuit configuration and implements broadband reception of 100 kHz to 1.3 GHz. FM/AM/SSB/CW reception is possible in the range 100 kHz to 29.7 MHz, and FM/wide FM/AM/SSB/CW reception is possible in the range 29.7 MHz to 1.3 GHz. The FM/AM receiver circuit uses double

23、 conversion with the first IF of 57.6 MHz and the second IF of 450 kHz. The SSB/CW receiver circuit uses triple conversion with the first IF of 57.6 MHz and the second IF of 450 kHz. The wide FM receiver circuit uses single conversion with the IF of 10.8 MHz. TH-F6A/F7E 5 CIRCUIT DESCRIPTION Fig.4 T

24、he first amplifier is divided into four bands: 100 kHz - 50 MHz, 50MHz - 108MHz, 108 MHz - 265 MHz, 265 MHz - 600 MHz, and 600 MHz - 1.3 GHz. The incoming signal from the antenna passes through a low-pass filter and a duplexer, and goes to an independent amplifier for each band. Then, the signal goe

25、s to the second common broadband amplifier (IC10) and its output is fed to the mixer (Q28) and heterodowned to the first IF. 2-1-1. FM/AM receiver circuit The signal heterodowned to the first IF of 57.6MHz passes through a 15kHz MCF (XF1), and unwanted signal components are eliminated. The resulting

26、 signal is amplified by the IF amplifier (Q26) and goes to the FM IC (IC5). The FM IC heterodowns it to the second IF of 450 kHz. In FM mode, the signal passes through a 12.0kHz external ceramic filter (CF3) and goes to the FM IC. The signal amplified by the internal IF amplifier is demodulated by t

27、he quadrature FM demodulation circuit using a coil (L19) and converted into an audio signal and output. In AM mode, the signal passes through a 4kHz external ceramic filter CF1 and goes back to the FM IC. It is amplified by the AM AGC amplifier built in the FM IC, an audio output from the FM IC as a

28、n audio signal. 2-1-4. AM bar antenna receiver circuit This unit incorporates an AM bar antenna, and either the bar antenna or the supplied antenna can be selected in the 520kHz-1.8MHz (SW) and 3.5MHz-10.1MHz (MW) bands (the initial value: bar antenna). The bar antenna has two kinds of tuners for SW

29、 and MW tuning, one of which is selected with a switching FET (Q32, Q48, Q52). The antenna is tuned with a varicap (D60) for AM tuning to select a desired signal. The signal from the bar antenna is amplified by and its impedance is converted by the buffer amplifier (Q59), and the resulting signal go

30、es to the common mixer (Q28) for the B band. The signal is routed over the same path for AM demodulation as for the supplied antenna after leaving the mixer. 19.05MHZ FINE2 D20,24 KV1566J TUNE IC4 TA4101F SSB DET SSB/CW Q22,29 UPA672TIC5 TK10931V SW FM AM SMB SQB Q23 LMX 2N OSCILLATOR 453KHz SW CF1

31、450KHz CF3 CF2 10.8MHz D25 DAN 235E TUNE D29 HVC 376B Q27 2SC 4915 OSCILLATOR Q26 2SC 4915 IF AMP Q28 MT6C 03AE MIX FINE1 UHF(6001300) UHF(265600) VHF(108265) HF HF IC10 MPC2746TB AMP LO 57.6MHz XF1 10.8MHz MCF Q24 2SC 4915 CF5 Q28 MT6C 03AE SW IC10 MPC2746TB AMP D57 HSC277 TUNE D60 KV1566J SW BAR A

32、NT Q6,Q4 Q48,52 2SK1824 Q32 2SK1830 MIX LO Q59 3SK320 RF AMP Fig.5 2-1-5. Audio signal The FM and AM demodulation signals output from the FM IC (IC5) pass through a low-pass filter consisting of a resistor and a capacitor, and goes to the switching FET (Q29), from which a switched signal is output t

33、o the control unit. The SSB/CW demodulation signal passes through an RC LPF, connects to the Q29 output section, and output to the control unit through a line common to all modes. The demodulation signal input to the control unit goes to the electronic volume (IC706, pin 16), the audio balance outpu

34、t with the A band is restricted, then the signal is output. It joins the A band demodulation signal and is processed in the same manner for both A and B bands. signal demodulated by the diode detection circuit is output. 2-1-2. SSB/CW receiver circuit In SSB/CW mode reception, the signal takes the s

35、ame path to CF1 as in AM mode. The signal input to the FM IC again is amplified by the AM AGC amplifier in the FM IC, then output from the AM IF output pin. The signal is fed to the third mixer (IC4) and converted to an audio signal and output. 2-1-3. Wide FM receiver circuit The signal converted to

36、 the first IF of 10.8 MHz passes through a ceramic filter CF5 for wide FM, and is amplified by the IF amplifier (Q24). The signal passes through ceramic filter CF2 again to eliminate unwanted signal components, and goes to the FM IF input (pin 7) of the FM IC. The input signal is amplified by the IF

37、 amplifier in the IC, demodulated by the quadrature FM demodulation circuit using an L18 coil, and TH-F6A/F7E 6 CIRCUIT DESCRIPTION FINE2 D20,24 KV1566J IC706 M62364 FP TUNE IC4 TA4101F SSB DET SSB/CW Q22,29 UPA672TIC5 TK10931V SW FM AM SMB SQB Q23 LMX 2N OSCILLATOR 453KHz SW CF1 450KHz CF3 CF2 10.8

38、MHz D25 DAN 235E 2-2. Mixer local oscillator 2-2-1. First mixer The local oscillator signal for the first mixer is supplied from the VCO-PLL circuit. To offset according to modes, the PLL switching frequency changes in FM/AM/CW, USB, LSB. 1st LOCAL (PLL Switching Frequency) Fig.6 FM/AMCWUSBLSB UPPER

39、Per 5kHzFM-2.5kHzFM-4.5kHz FM-0.5kHz LOWERPer 5kHzFM-2.5kHzFM-4.5kHz FM-0.5kHz 2-2-2. Second mixer The local oscillator signal of the second mixer uses 57.15MHz which is three times as high as the 19.05MHz crystal oscillator (X3) output. This local oscillator signal is used to (i) implement fine ste

40、ps during fine tuning and (ii) offset during SSB/CW reception. 2rd LOCAL (Oscillator Frequency) (i) Fine tuning function When the fine tuning function is ON, the PLL comparison frequency is 5 kHz (5kHz step). The receive frequency of 10Hz steps as a set is implemented by operating the local oscillat

41、or signal of the second mixer in 33.3Hz steps in the 5kHz frequency range. The frequency is varied by 57.15 MHz +/- 2.5 kHz by changing the voltage applied to the varicap (D29) installed in the local oscillator circuit. (ii) Mode offset The IF frequency is adjusted by 2 Hz in SSB mode so that the de

42、modulated signal passes through the center of the 4kHz ceramic filter (CF1). The frequency is adjusted by varying the local oscillator frequency. FM/AMCW(Fine Tuning)USB(Fine Tuning) LSB(Fine Tuning) UPPER57.15MHz 57.15MHz+2.5kHz 57.15MHz-2.5kHz LOWER57.15MHz 57.15MHz+2.5kHz 57.15MHz-2.5kHz 2-2-3. T

43、hird mixer The third mixer (IC4) works in SSB/CW mode only. The local oscillator signal of 450 kHz +/- 2 kHz is produced in SSB mode to restore 2kHz correction (offset), and the signal of 450 kHz - 800 Hz is produced to generate an 800Hz beat frequency in CW mode. A demodulation signal is produced i

44、n SSB, and a 800Hz beat signal is produced in CW. 3rd LOCAL (Oscillator Frequency) FM/AMCWUSBLSB UPPER450kHz450kHz+800Hz 450kHz+2kHz450kHz-2kHz LOWER450kHz450kHz+800Hz450kHz-2kHz450kHz+2kHz 2-3. AGC circuit The AGC is controlled by using the output from the RF AGC built into the FM IC (IC5). The AGC

45、 is controlled by controlling the bias current of the IF amplifier (Q26) and the forward current of the pin diode (D32) for the attenuater. In non-FM mode, the AM AGC circuit built-into the FM IC is also used. 3. Control 3-1. Reset and backup circuits The CPU reset signal is generated with the CR ti

46、me constant by detecting a rising edge of the M4 line voltage with the voltage detection IC (IC709). If the voltage supplied to the TH- F6/TH-F7 decreases and the M4 line voltage falls below the detection voltage of the voltage detection IC (IC710), the CPU (IC705) detects it through the interrupt pin, backs up data in the EEPROM (IC704), and shuts the power off. 3-2. Voltage detection processing The voltages are measured through the A/D port of the CPU (IC705) for processing. The battery voltage is supplied through a resistor, and a warning soun