TR-7400A_serv.pdf

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1、 Your KENWOOD Model TR-7400A is a high-quality 2-meter transceiver for use in ama- teur radio mobile stations as well as base stations . It contains a PLL frequency syn- thesizer developed and engineered through KENWOODs elaborate VHF technology to provide high performance and outstanding technical

2、characteristics . The TR-7400A is capable of transmitting or receiving F3 FM signals on up to 800 Chan- nels at intervals of 5 kHz. having 25W RF output power . CONTENTS SPECIFICATIONS . 3 FINAL TRANSISTOR SPECIFICATIONS . 4 BLOCK DIAGRAM . 5 CIRCUIT DESCRIPTION . 6 PARTS ALIGNMENT . 11 PC BOARD PA

3、UNIT (X45-1090-10) . 13 PD UNIT (X50-1380-10) . 14 VCO UNIT (X50.1370.10) . 15 INDICATOR UNIT (X54-1210-10) . 16 RX UNIT (X55-1150-10) . 17 TX UNIT (X56-1230-10) . 18 PARTS LIST . 19 PACKING . 25 DISASSENIBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 TROUBLES

4、HOOTING . 29 LEVEL DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 ADJUSTNIEIUTS . 33 SCHEMATIC DIAGRAM . 40 SPECIFICATIONS GENERAL Semiconductors Frequency Range Frequency Synthesizer Synthesizer Stability Mode Number of Channel Operating Temperature Power

5、 Voltage Grounding Antenna lmpedance DC Current Dimension Weight Transistors 58 FETs 8 I C s 19 Diodes 63 144.00 to 147.995 MHz Digital (TTL Logic) control of phase locked VCO Less than k750 Hz at 2 5 FM 800 -20 to +50c 11.5 VDC to 16.0 VDC (13.8 VDC as reference) Negative grounding 50 52 Less than

6、1A in receive with no input signal Less than 8A in transmit (HI) Less than 4.5A in transmit (LOW) (at 13.8 VDC) 182 mm (7-3116) wide 74 mm (2-718) high 270 mm (10-518) deep Approx. 2.8 kg (6.2 Ibs.) TRANSMIT SECTION RF Output Power High 25 watts (min.) Low approx. 5 watts (adjustable up to 15 watts)

7、 Modulation Variable reactance direct shift Max. Frequency Deviation k5 kHz Spurious Radiation Less than -60 dB Touch Tone Input Impedance 600 52 Microphone Dynamic microphone with PTT switch, 500 52 RECEIVE SECTION Circuitry Intermediate Frequency Squelch Sensitivity Pass Band Width Selectivity (2

8、Signal) Image Rejection Spurious Interference lntermodulation Audio Output OPTION i) Tone Squelch Tone Deviation Encorder Response Frequency Stability Tone Squelch Open Sensitivity Tone Distortion ii) Tone Burst Burst Time Double superheterodyne 1st IF 10.7 MHz 2nd IF 455 kHz Less than 0.4 pV for 20

9、 dB quieting (Less than 1 ,uV for 30 dB SIN) Less than 0.25 ,uV More than 12 kHz at 6 dB down More than 72 dB at 30 kHz of adjacent channel More than 70 dB More than 60 dB More than 66 dB More than 1.5 watts across 8 52 load (10% distortion) k0.5 kHz (adjusted) Less than 0.5 sec. Less than 21% Less

10、than SlNAD 10 dB Less than 5% Approx. 0.5 sec. (adjusted) NOTE: The circuit and ratings may change without notice due to development in technology. Final Transistor (2N6083) Specifications Maximum Ratings TA = 2 5 O (Unless otherwise specified) Characteristics Standard TA = 25OC (Unless otherwise sp

11、ecified.) Item Unit Ratings V cso V 36 Symbol VCEO V 18 LTPD level Condition 5 5 FE Cob VEBO V 4 Minimum 1 1 VCE = 5V, IC = 1A 5 5 1 / VCB = 15V, f =0.1 MHz 1 Standard value Maximum 5 Vcc = 12.5 V, POUT =30W ) 5.7 dB 10 1 f = 175 MHz, Vcc = 12.5 V, POUT =30W rl 1 6 5 % 10 1 f = 175 MHz, ICES VCE= 15

12、 V, TC = 55OC 10 mA 5 1 I c A 4 Unit VCB = 15 V ICBO 1 - r n A BVCES Ic = 15 mA V PD T A = c W 6 5 BVCEO BVEBO - Stud torque inIb 6.5 Ic = 100 mA V - Tstg c -65 to 200 - IE = 5 mA 4 , V BLOCK DIAGRA! RX UNlT (X55-1150-10) r- - - - - I I I I L ,-,-,-, + - - - To 0 1 3 (OFF circuit of VCO output) 0 4

13、5 v UNLOCK Fig. 3 PHASE DETECTOR Block Diagram Indicator PROGRAMMABLE COUNTER AND TX-OFFSET ing counter which counts in the order of 0, 4, 3, 2, 1, 0 CIRCUITS (5), 4, 3, . receiving input pulses, assuming that preset These circuits, consisting of IC5 to IC12, are basically a MODULO-N PROGRAMMABLE co

14、unter of IC5 to IC7 added with an EXTENDER consisting of a D-flip-flop of lClO and a logic circuit of IC8, 9, I I and 12. It belongs to the high-speed scaling method. Fig. 4 shows the opera- tion of the circuits. The operation is simply described below. A division ratio is preset in the MC74416 of I

15、C5 to IC7 with a BCD code. The division ratio preset lies be- tween 400 and 799 in relation to digital indication (144.00 - 147.99). While, since the IF signal entering the MC 74416 is 5.37 - 9.36 MHz to eliminate beat interference in reception, the division ratio must be 537 - 936 actually. For thi

16、s purpose the gate, No, serves to raise the division ratio by 137. The gate circuit, U and D, shifts frequency by f600 kHz for repeater operation which is equivalent to the divsion ratio of 137 f 60. MC74416 is a decrement- value is 5 and PE is 0 (L level). But output becomes 1 (H level) only when t

17、he count is 0. It means that five input pulses make one out- put pulse and the frequency is divided to 115. With three ICs connected in cascade, the division ratio can be raised up to 999. IClO is a high speed D-flip-flop which improves the operating frequency of MC74416, 8 MHz (min.), by a factor o

18、f two or more with the aid of gates A and B. Fig. 4 shows the case where the least significant digit of the actual division ratio, Ns, is 7. Although resetting should be done at the rise of input pulse and presetting should be done at the decay of the input pulse when the count has become three, the

19、 level at A is set to L at the count of five and it becomes the output of IC10-1 at the next pulse. This output (01) resets the MC74416 and presets it to N at the same time, but counting is not per- formed since PE remains at the L level during the next Fig. 4 Block Diagram of PROGRAMMABLE COUNTER a

20、nd TX-OFFSET Circuit CIRCUIT DESCRIPTIONS input pulse and it is reset. The operating frequency has been improved because resetting and presetting are done in one cycle of input pulse but not in half a cycle, and the delay time, t2, of the high speed D-flip-flop in lClO is much smaller than the delay

21、 time, t l , from IC5, 6 and 7 and logic circuit to point A. Next, operation is explained in relation to the TX off- set switch setting. 1 +600 During reception, this is the same as in (2). During transmission, SR 1 is turned on and becomes U in Table 2. Gate U therefore opens and gates No and D are

22、 closed. At this setting, Ns = I N + 197 (137 + 60), and it operates as an extender when IC5, IC6 and IC7 take code 8, 0 and 5 respectively, to perform division of N + 197. 2 No (SIMP) (F) and (G) make up No in Table 2. Gates No and U open and gate D IS closed. At this setting, the relation, Ns = N

23、+ 137, holds between preset value N and actual divi- sion ratio Ns. It is enough to decrement the counter after division of N (decrernenting) has completed and perform resetting and presetting just when the count has become 137. For this purpose, IC5, IC6 and IC7 do not take code 8, 6 and 3 respecti

24、vely (as already described), but it operates as an extender at code 5 and performs division of N + 137. Since the gate is of code 197 (137 + 60), the extender operates before this code triggers the circuitry. 3 -600 During reception, SR2 is turned on as in (2). During transmission, gates No, U and D

25、 open as D in Table 2. At this setting, Ns = N + 77 (137 - 60), it operates as an extender to perform division of N + 77 when IC5, IC6 and IC7 carry code 9, 2 and 5 respectively. At this time, the extender operates at code 77 even when all gates are open Table 1 shows the case of N = 400 (144.00 MHz

26、). - TSBl Active filter n TONE SQUELCH CIRCUIT *d Fig. 5 shows the circuit. The tone squelch circuit employed in this equipment is the so-called CTCSS (con- tincocs tone controlled squelch system). Tone signal of a certain frequency is superimposed with audio signal at the transrlission side, which

27、is separated at the reception side to drive the squelch circuit. When set to SOU (tone squelch) as shown in Fig. 5, a voltage is applied to TSBI and TSB2. When no signal is received or signal received does not have tone component, 020 and 21 remain off and no sound is reproduced since the voltage of

28、 TSB2 is applied to the base of Q13 through D l 4 and the AF circuit is turned off. When signal including tone component is received, the tone signal separated from discriminator output with 019, LPF and amplifier, is applied to an active filter. The active filter which serves to the tone frequency

29、and 0 1 1 give steep characteristics at the frequency. It selects tone output equal to the active filter and its output passes through D l 1 (on during reception) and is detected in D l 2 and 13. It turns on 020 and then 021 and turns off Q13 and the AF circuit (014) operates to reproduce sound from

30、 speaker. In the AF circuit, an active type high-pass filter of 024 and 25 cuts off tone signal output to arnplify audio signal alone. During transmission, 022 is turned on, and the active filter and 0 1 1 forin an oscillating circuit to deliver output with the same frequency as of the active filter

31、. This octpct is passed through VR3 and modulated in TX unit together with audiosignal. The maximum frequency deviation for audio signal is f5 kHz and that for tone com- ponent for tone squelch is k0.5 kHz, which results in a ratio of about -20 dB. This would result in buzzing sound when unmodulated

32、 signal is received, but a high-pass filter of 300 Hz in cutoff frequency corporated in the equipment reduces the tone level to prevent buzz. Operation is the same even in the SUB (sub-audible) since a voltage is applied to TSBI, and sub-audible control is performed. I I 2 13 H8D5022 I I Dlsc L -A O

33、utput e L.P.F. AMP To base of 013 Fig. 5 TONE SQUELCH Circuit DESCRIPTION Table 4 Squelch Active Filter List Table 5 Tone Burst Oscillator Module List Frequency (Hz) 88.5 94.8 100.0 103.5 107.2 110.9 114.8 118.8 128.0 127.3 131.8 136.5 141.3 146.2 151.4 156.7 Parts number L79-0408-05 L79-0409-05 L79

34、-0410-05 L79-0411-05 L79-0412-05 L79-0413-05 L79-0414-05 L79-0415-05 L79-0416-05 L79-0417-05 L79-0418-05 L79-0419-05 L79-0420-05 L79-0421-05 L79-0422-05 L79-0423-05 VCT CIRCUIT Frequency (Hz) 1800 1950 2000 2100 21 50 2200 2250 2400 2550 The equipment incorporates a VCT circuit at the out- put side

35、of the transmission mixer to improve spurious radiation and output levels in the wide range from 144 to 148 MHz. Varicaps D2, 3 and 4 are connected to tuning coils L11, 12 and 13 through temperature compensation capacitors. Voltages divided from common 9V (C9) with R62 and 61 (145.5 MHz), VR61 (144.

36、5 MHz) VR62 (146.5 MHz) and VR63 (147.5 MHz) and switched with the MHz switch are applied to D2, 3 and 4. Parts number TBM-1800 TBM-1950 TBM-2000 TBM-2100 TBM-2150 TBM-2200 TBM-2250 TBM-2400 TBM-2550 FINAL CIRCUIT The output of the TX unit iabout 1.4 W, 50-ohm) load) is amplified to about 10 W (50-o

37、hm load) by 0 1 of the PA unit and to about 35 W (50-ohm load) by 0 2 and delivered to the ANT terminal by way of an ANT switching diode and a LPF. To protect the final transistor (02), the input power to 0 2 is limited by controlling the collector voltage of the driver (015 of TX unit and 01 of PA

38、unit) by detecting SWR of antenna with 03, 10 and 11. When power is low, the circuit is used to reduce the voltage across the SB terminal with VR5. Large aluminum die-cast heat sinks In combination w t h Motorola transistors, MRF208 and 2N6083, ensure high reliability. Knob (SQU) (K21-0703-04) Knob

39、(VOL) (K2 1-0704-04) Knob (MHz) (K2 1-0702-04) 4P microphone (E06-0403-05) Case (8) (A01-0704.12) 2P connector (E07-0251-05) Case (A) (A01-0703-22) PARTS ALIGNMENT LED LED (838-0302-05) (838-0301-05) Knob (MAIN) (K210705-04) 1 sub panel Knob (5 kHz) Knob (TX OFFSET) (A22-070103) (K29-0702-04) (K23-0

40、702-04) Mounting bracket Mounting rail Earphone jack stopper (J90-0045-04) (E 11-0003-1 5) (J51-0006-15) I I I 4P socket (E08047 1-05) Heat sink (F 20-0502-05) I PARTS ALIGNMENT DISPLAY UNlT PD UNlT (X54-1210-10) (X50-1380-10) I TX UNlT (X56-1230-10) RF meter ADJ. I I I V A V R Tone burst time ADJ.

41、I I Tone oscillator module PA UNlT (option) (X45-1090-10) VCO UNIT RX UNIT (X50-1370-10) (X55-1 150-10) Center meter point I I s meter ADJ. I I TON L O a - - . L O ? - rn . . Eh 20 g *- 0 . . - g z ; - 7 O r ; . 9 5 . hlFn * - 0- h * CC) Log= - w - L n r-. a- LoEfl 7 4 4 h - - - 7 E m d g%: * - r -

42、. O 0 n m ci ; O,%n ? - b g L LT *- G K* a , - * -h a - O 2 yJ - -0 7 3 sb, L n - 0 m - h-2 aa, : rn- 2% $ K G 5 2 hlr; - - h l a a a PC BOARD TX UNIT (X56-1230-10) 1 r- O cj - 0 - g d 8 : V) C . . LC) 2 ) - PARTS LIST * : New Darts TOTAL I Ref. No. Parts No. I Description I Ref. No. 1 Parts No. 1 D

43、escription Re- mark I CAPACITOR I 18-0802.05 Relay socket E22-0207-05 Lug E23-0047.04 Terminal x 1 I E30-0355.05 Wire (for speaker) E31-0403-05 Connector with lead E31-0404.15 Connector with lead E31-0405-05 Connector with lead E31-0406-05 Connector with lead E31-0407-05 Connector w i t h lead E31-0

44、408-05 Connector w i t h lead E31-0409-05 Connector w i t h lead E40-0513-05 Mini connector wafer E40-0616-05 Mini connector housing x 2 Tone filter E40-0713-05 Mini connector wafer E40-0913-05 Mini connector wafer E40-1013.05 Mini connector wafer CE04WlA470 Electrolytic 4 7 F 10WV CK45FlH103Z Ceram

45、ic 0 . 0 1 F +80%,-20% CK45D1 H102M Ceramic lOOOpF f 2 0 % CK45F1 H103Z Ceramic 0 . 0 1 F +SO%,-20% CC45SLlHIOI K Ceramic IOOpF ? 10% RESISTOR SEMICONDUCTOR Transistor 2SD235 (Y. 0 ) F05-1031-05 Fuse (lOA) x 2 F19-0601.14 Blinding plate A (Insde) F19-0602-04 Blinding plate B (Outsde) F20-0078-05 l n

46、sulating plate F29-0014-05 l nsulating washer Diode V068 Diode IS1555 L E D with holder L E D with holder Diode IS1555 cushion Cushion Vibration protector (rubber) I POTENTIOMETER I Case (inside) Buffer fixture Styrene foam cushion (Upper) Styrene foam cushion (Lower) Protection coyer Polyethylene bag (60 x 110 m m ) Polyethylene bag (200 x 200 mm) Polyethylene bag (125 x 250 m m ) VR61-63 RIP-3025-05 Semi-fixed resistor 1 0 k R VR101.102 R19-9401-05 Variable resistor I I 571, 72 5102 S103 R L l O l SWlTCHlRELAY