R-820_serv.pdf

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1、 KENWOOD v:;-1 .: VB flRHnMI R-820 HIGH PERFORMANCE HF AMATEUR BAND RECEIVER CONTENTS R.820 SPECIFICATIONS . . . 3 FEATURES . 4 BLOCK DIAGRAM . 5 GENERAL . , . 6 CIRCUIT DESCRIPTION . 7 FUNCTIONAL DESCRIPTION . 9 MODIFICATION OF THE TS-820 . 11 PANEL CONTROLS . 13 PARTS ALIGNMENT/PACKING . 14 PARTS

2、LIST . 31 EXPLODED VIEW . . 44 DISASSEMBLY . . . 45 TROUBLESHOOTING . 47 LEVEL DIAGRAM . . 50 ADJUSTMENT . 51 OPTION . 58 SCHEMATIC DIAGRAM . 59 CONNECTOR ALIGNMENT. .60 -. I l SPECIFICATIONS Frequency Range 1 60 meter band 80 meter band 40 meter band 20 meter band 1 5 meter band 10 meter band A 10

3、meter band B 10 meter band C 10 meter band D 1 1 9 meter band (WWV1/JJY Shortwave band: 49 meter band 31 mei;r band 25 metir band 1 6 meter band 1.8 3.5 7.0 14.0 21.0 28.0 28.5 29.0 29.5 15.0 5.9 9.4 11.5 17.7 2.0 MHz 4.0 MHz 7.5 MHz 14.5 MHz 21.5 MHz 28.5 MHz 29.0 MHz 29.5 MHz 30.0 MHz 15.5 MHz 6.4

4、 MHz 9.9 MHz 12.0 MHz 18.2 MHz Notch Filter Attenuation More than 50 dB Frequency Stability Within 1 00 Hz during any 30 minute period after warm up within 1 kHz during the first hour after 1 minute of warm up. Antenna Impedance 50 75J) (unbalanced) AF Output More than 1.5W (8fi load, 10% distortion

5、) AF Load Impedance 4 16Q for both speaker and headphone Mode SSB, CW, AM, RTTY Receiver Sensitivity SSB 0.25 juV (SW Band 0.5 pV) S + N/N 10 dB or more AM 1.5 jiV (SW Band 3 0V) S + N/N 10 dB or more Image Ratio Better ihan 80 dB (SW Band better than 50 dB) IF Rejection IF Frequency is 90 dB or mor

6、e down from output signal (SW Band more than 40 dB) Receiver Selectivity CW(025) more than 250 Hz (-6 dB), less than 500 Hz (-6 dB) (*,) CW (0.5) more than 500 Hz ( 6 dB), less than 850 Hz (-60 dB) (*2) SSB (2.4) more than 2.4 kHz (-6 dB), less than 3.9 kHz (-60 dB) AM (6) more than 6 kHz( 6dB). les

7、s than 12 kHz (60 dB) Variable Bandwidth CW (05) 150 Hz - SSB (2.4) 600 Hz AM (6) 4.3 kHz 500 Hz (-6 dB) fully variable (*3) 2.4 kHz (-6 dB) fully variable 6 kHz (-6 dB) fully variable (M Installed optional filter-YG-455CN *2 Installed optional filter-YG-455C *3 Installed optional filter-YG-88C and

8、YG-455C *4 Installed optional filter-YG-88A Power Consumption AC 120V, 30W DC 13.8V, 1.6A Power Supply AC 100, 120, 220, 240V, 50/60 Hz DC 1 2 1 5V Semiconductors and Tubas ICs FETs Transistors Diodes Tube 40 34 89 170 1 Dimensions 13-1/8 (W)x6 (H)x 13-3/16 (Protection not included) (D) NOTE: The ci

9、rcuit and ratings may change without notice due to development in technology. FEATURES 1High Performance HF Amateur Band Receiver The R-820 is KENWOODS high performance communication receiver, designed to meet diversified demands in various operation modes in the HF band. A highly refined version of

10、 the TS-820s receiver section, the R-820 covers all HF amateur bands (1.8 MHz 297 MM/) plus WWV and selected SW Bands, and operator; in the CW, SSB, and AM modes. 2. Full Transceiver Capability In combination with a TS-820 series tranceiver, the R-820 can provide split frequency operation. Shared ME

11、T and VFO frequencies provide full transceive operation with identical transmitting and receiving frequency, as well as VFO transceive operation. 3. Variable Bandwidth Tuning (VBT) IF bandwidth is continuously front panel adjustable, making optimum IF bandwidth available for any operating condition.

12、 This feature is completely independent of the IF Shift. 4. 50 kHz Notch Filter The notch circuit effectively nulls nearby interfering signals The R-820 employs a fixed notch filter. The BFO and local oscillator are simultaneously varied so as to obtain equivalent changes in the notch frequency. 5.

13、Double Tuned RF Circuits for Improved Cross Modulation (2-Signal) Characteristics Improved front end circuit elements and optimized level distribution have greatly enhanced intersignal perform- ances such as intermodulation and overload characteristics. The introduction of double-tuned RF cir- cuits

14、 provides increased selectivity and sensitivity. 6. IF Shift to Cope with all Receiving Conditions The IF Shift circuit, one of the highly evaluated features used m the TS-820 transceiver, has also been incorporated in the R-820, providing remarkable interference rejection performance, frequency res

15、ponse, and CW pitch control. 7. Digital Display Provides Accurate Frequency Indication The Digital frequency readout provides precise indication to the 100 Hz order, any band, any mode, including the shortwave bands. 8. Superior Tuning Operation The combination of analog and digital readouts provide

16、s maximum nonvfinipnr nnd flevibility during operation. 9. Four Shortwave Bands with an AM Filter The R-820 also covers the popular HF broadcast bands of 49m, 31m, 25m, and 16m. It is supplied with a built-in 455 kHz AM filter; an 8.83 MHz AM filter (YG-88A) is available as an/option. 10. Transmitte

17、r Signal Monitor Transmitter output can be monitored with the R-820 for checking final sound quality. Monitor level is front panel adjustable. 11. Optional IF Filters Filters optionally available are: 8.83 MHz CW filter YG-88C, AM filter YG-88A, and 455 kHz CW filter YG-455C (pass band: 500 Hz) and

18、YG-455CN (pass band: 250 Hz). 12. Additional Filter Switching Additional filters are appropriately selected by the MODE switch. Filter pass bands of 0.25 kHz, 0.5 kHz. 2.4 kHz, and 6 kHz can be selected by means of the Filter Switch. 13. Adjustable Noise Blanker Level and Audio Frequency Response Th

19、e balanced-gate noise blanker circuit is provided with a front panel noise threshold adjustment. This is especially useful when noise levels are relatively low. A front panel tone control for audio response shaping is also provided. 14. 10 dB-Stepped RF Attenuator (0 40 dB) The 1 0 dB stepped attenu

20、ator provides up to 40 dBs RF attenuation making it possible to receive strong local signals or low band stations operating at night. m 15. S-Meter with dB/VV Scale The S-meter is provided with a dB/V scale which can be used for field intensity measurements in combination with the RF step attenuator

21、. 16. Full Accessory and Connecting Features The R-820 receiver is complete with full accessory and connecting features such as: 25 kHz marker, display hold switch, transceive/separate selector, standby switch, FIXED channel oscillators, NOTCH. FIX, VFO, and RIT indicators, PHONE PATCH OUT jack, ter

22、minals for IF output a observation (50 kHz) and pan display connection (8.83 MHz), and a recording jack. * .:.- BLOCK DIAGRAM t r GENERAL The R-820 receiver is triple conversion superheterodyne for the amateur bands, and quadruple conversion superheterodyne through an additional 29.5 MHz intermediat

23、e frequency for the shortwave bands. Full amateur band coverage consist of 1.8, 3.5, 7.0, 14.0, 21.0. 28.0, 28.5, 29.0, and 29.5 MHz bands along with 15 MHz WWV (JJY). Shortwave coverage consists of the 49m (5.9 6.4 MHz), 31m (9.4 9.9 MHz), 25m (11.5 12.0 MHz), and 16m (17.7 18.2 MHz) Bands. Recepti

24、on of CW, SSB, RTTY, and AM are all possible. The 1st, 2nd, and 3rd intermediate frequencies are 8830 kHz, 455 kHz, and 50 kHz. The 1st IF stage uses crystal filters with pass bandwidths of 2.7 kHz (SSB; supplied), 6 kHz (AM; optional), and 0.5 kHz (CW; optional). The 2nd IF stage uses ceramic filte

25、rs of 6 kHz (AM; supplied) and 2.7 kHz (SSB: supplied), and optional crystal filters of 0.5 kHz (CW) and 0.25 kHz (CW). For enhanced selectivity, the R-820 features continuously-variable IF bandwidth, achieved by combining the 1st and 2nd IF filter responses, and the IF Shift feature. A T notch filt

26、er is incorporated in the 3rd IF stage. Amateur frequencies can be read by both the dial and Digital frequency readouts. Shortwave frequency is read by the Digital display only. Performance is assured in the 1st and 2nd mixers and the converter by employing dual-gate MOS FETs. (Refer to Figure 1.) R

27、F circuits are also totaly of dual-gate MOS FET configuration for increased selectivity, signal-to-noise ratio, and AGC performance. The R-820 receiver is capable of operating with the TS-820 transmitter as a complete transceiver. Fig. 1 SSB Filter Variable Bandwidth Characteristic Fig. 2. T Notch F

28、ilter Attenuation Characteristic I * l r CIRCUIT DESCRIPTION i *Coil Pack Unit (X44-1230-00) The Coil Pack Unit is the same basic design as that used in the TS-820 transceiver, excepting the RF section, which is. double-tuned for higher selectivity. *RF Unit (XX-1240-00) The RF Unit consists of an R

29、F amplifier, 1st mixer, and block bias circuits, and assembles to the Coil Pack Unit. *IF A Unit (X48-1190-00) The IF A Unit consists of an 8 pole crystal filter for 8830 kHz, filter and gate circuits for the noise blanker, 2nd mixer, ceramic and crystal filters for the 2nd IF at 455 kHz, 3rd mixer,

30、 S-meter amplifier, and filter preset switches. The standard supplies filters pre a YG-88SW (8830 kHz) and CFJ455K3 (455 kHz) both for SSB, and CFR455H for AM. Optional filters are the YG-88A (AM) and YG-88C (CW) both for the 1st IF, and YG-455C (CW) and YG-455CN (CW) both for the 2nd IF. *IF B Unit

31、 (X48-1200-00) The IF B Unit contains 3rd IF (50 kHz) circuits, consisting of the notch filter, notch filter switch circuit, product detector, AM detector, switching AM detector switching circuit, and AGC amplifier. *NB Unit (X45-1330-00) The NB Unit consists of a noise amplifier for noise blanking.

32、 *AF AVR Unit (X49-1080-01) The R-820s AF AVR Unit is identical to that of the TS-820 transceiver, and includes the audio power amplifier, 9V regulated power supply, FET bias supply, and RIT adjust circuits. *PLL Assy Unit (X60-1010-01) The PLL Assy Unit consists of the PD (Phase Detector) Unit (X50

33、-1 340-01) and the VCO (Voltage Controlled Oscillator) Unit (X50-1 330-00). The R-820 has a front panel switch for turning the HET oscillator on and off; for transceiver operation, HET output accepted from the TS-820 forms the PLL loop. The PD Unit has separate crystals for each band, two mixers, wa

34、veform shaping, and phase comparator. It generates control for the VCO, based on BFO output. It also provides a pure electronic IF Shift loop by using the incoming carrier signal. The VCO Unit contains the voltage controlled oscillators for each band, buffer amplifier, and oscillator output shut-off

35、 circuit for loop unlock. Oscillation frequencies are controlled by voltage from the PD Unit. Band switching for both units is by electronic (diode) switches. *CAR Assy Unit (X60-1040-OO) The CAR Assy Unit consists of IF Shift and VBT control circuits, and a local for the 2nd mixer. The CAR-1 Unit (

36、X50-1480-00) has an oscillator for IF Shift, crystals for 8831.5 kHz (USB) and 8828.5 kHz (LSB). switch circuit, and VXO circuit. It also contains an oscillator frequency shift circuit for AM reception. The CAR-2 Unit (X50-1460-00) consists of oscillators for the 2nd mixer and VBT, which is equipped

37、 with an 8375 kHz (NORM) crystal and VXO circuit. * Local OSC Unit (X50-1440-00) The Local OSC Unit accepts signals from CAR-1 and 2 to produce a 455 kHz mixed output, and also produces a 505 kHz signal by mixing the 455 kHz mixed output with the 50 kHz NOTCH signal generated by its own oscillator.

38、It also has 50 kHz signal generator. The 50 kHz signal is used as a BFO signal for the product detector, and the 505 kHz signal is used as a local signal for the 3rd mixer. *FIX Unit (X50-1450-00) The FIX Unit consists of an oscillator for the 4 fixed channels, and a 6V power supply for block bias.

39、* Indicator Unit (X54-1180-00) This unit provides VFO, FIX, RIT, and NOTCH indication. The VFO and FIX indicators also function during transceiver operation with the TS-820. *VR ASSy (X54-1340-00) The VR Assy has variable resistors for monitor level control, NB level control, and tone control. * Swi

40、tch Assy (X41-1130-00) During full transceive operation, the TRCV activates the VFO and HET switching circuits. position * Relay Assy (X43-1190-01) The Relay Assy consists of a standby relay, low voltage DC p.ower supply capacitors, and the 5-volt stabilized power supply for the PLL circuit. The sta

41、ndby relay switches block biases and VFO power during transceive operation. *VFO Assy (X40-1110-00) The receivers overall frequency stability depends on that of the VFO, since the PLL circuit is controlled by VFO output. VFO frequency is 5.0 MHz to 5.5 MHz. *5V-AVR Assy (X43-1220-00) The 5V-AVR Assy

42、 supplies regulated 5V DC to the Counter assy. * Marker Assy (X52-0005-01) The 100 kHz synchronizes output from 01 is waveform shaped by diode D1, Q2 and Q3 multivibrator. The 25 kHz multivibrator output is amplified by 04 and fed to the receiver input. * Counter Assy (X60-1020-00) The Counter Assy

43、consists of the Counter Mixer unit (X54-1150-00) and the Counter unit (X54-1160-00), both .-.- - .TFjirJ- :.- * CIRCUIT DESCRIPTION contained in a rigid shielded case. The counter mixer synthesized operating frequency by mixing the PLL and carrier outputs; Counter unit output drives the external 6-d

44、igit fluorescent display tube. * Converter Assy (X44-1250-00) Shortwave broadcasts are crystal converted to the 29.5 MHz intermediate frequency. Diode switching is employed for converter selection. The Converter Assy also has a frequency converter for the Digital display, control circuits for HET/VF

45、O switching, monitoring, frequency display erasure, and the low voltage rectifier circuit. * Frequency Configuration for Triple Conversion The 1 st, 2nd, and 3rd intermediate frequencies for the triple conversion system are 8830 kHz. 455 kHz, and 50 kHz. Unlike conventional receivers, the R-820 uses

46、 high-selertivity IF filters for each stage after the 1st mixer. Crystal converters are used for each of the shortwave bands. Table 2 Table 1 Mode LSB USB CW RTTY AM Freq. kHz 8828.5 8831.5 8831.5 8828.5 8830.0 Band WWV/JJY 1.8 3.5 7 14 21 28 28.5 29 29.5 HETMHz 205 7.3 , 9.0 12.5 19.5 26.5 33.5 34.0 34.5 35.0 VCO 23.83 - 10.63 - 12.33 15.83 - 22.83 - 29.83 - 36.83- - 37.33 - 37.83