VERTEX YAESU FT-817 Service Repair Manual

©2003 VERTEX STANDARD CO., LTD. Printed in Japan. (E137790A) Technical Supplement FT-817 HF / VHF / UHF All Mode Transceiver Introduction This manual provides technical information necessary for servicing the Yaesu FT-817 HF & V/UHF-Bands Trans- ceiver. It does not include information on installation and operation, which are described in the FT-817 Operating Manual provided with the transceiver, or on accessories which are described in their manuals. The FT-817 is carefully designed to allow the knowledge- able operator to make nearly all adjustments required for various station conditions, modes and operator preferenc- es simply from the controls on the panels, without open- ing the case of the transceiver. The FT-817 Operating Man- ual describes these adjustments, plus certain internal set- tings. Servicing this equipment requires expertise in handling surface mount chip components. Attempts by unqualified persons to service this equipment may result in perma- nent damage not covered by warranty. For the major circuit boards, each side of the board is identified by the type of the majority of components installed on that side. In most cases one side has only chip components, and the other has either a mixture of both chip and lead compo- Contents Specification .................................................. 2 Exploded View & Miscellaneous Parts ..... 3 Block Diagram ............................................... 5 Circuit Description ....................................... 7 Alignment ..................................................... 13 Interconnection Diagram ........................... 23 nents (trimmers, coils, electrolytic capacitors, packaged ICs, etc.), or lead components only. While we believe the technical information in this manual is correct, VERTEX STANDARD assumes no liability for damage that may occur as a result of typographical or other errors that may be present. Your cooperation in pointing out any inconsistencies in the technical information would be appreciated. VERTEX STANDARD reserves the right to make changes in this transceiver and the alignment procedures, in the interest of technological improve- ment, without notification of owners. Board Unit (Schematics, Layouts & Parts) MAIN Unit ............................................................... 25 PLL Unit ................................................................... 57 REF Unit ................................................................... 65 PA / FINAL Unit ...................................................... 71 PANEL Unit ............................................................. 89 VR Unit ..................................................................... 99 TCXO-9 Unit (Option) .......................................... 100 VERTEX STANDARD CO., LTD. 4-8-8 Nakameguro, Meguro-Ku, Tokyo 153-8644, Japan VERTEX STANDARD US Headquarters 10900 Walker Street, Cypress, CA 90630, U.S.A. International Division 8350 N.W. 52nd Terrace, Suite 201, Miami, FL 33166, U.S.A. YAESU EUROPE B.V. P.O. Box 75525, 1118 ZN Schiphol, The Netherlands YAESU UK LTD. Unit 12, Sun Valley Business Park, Winnall Close Winchester, Hampshire, SO23 0LB, U.K. VERTEX STANDARD HK LTD. Unit 5, 20/F., Seaview Centre, 139-141 Hoi Bun Road, Kwun Tong, Kowloon, Hong Kong

2 Specifications General Frequency Range: Receive: 100 kHz-30 MHz 50 MHz-54 MHz 76 MHz-108 MHz (WFM only) 87.5 MHz-108 MHz (EU) 108 MHz-154 MHz (USA) 144 MHz-148 (146) MHz (Other markets) 430 (420) MHz-450 (440) MHz Transmit:160-6 Meters 2 Meters 70 Centimeters (Amateur bands only) 5.1675 MHz Alaska Emergency Frequency (USA only) Emission Modes: A1 (CW), A3 (AM), A3J (LSB/USB), F3 (FM), F1 (9600 bps packet), F2 (1200 bps packet) Synthesizer Steps (Min.): 10 Hz (CW/SSB), 100 Hz (AM/FM) Antenna Impedance: 50 Ohms, Unbalanced (Front: Type BNC, Rear: Type M) Operating Temp. Range: –10 °C to +60 °C (+14 °F to +140 °F) Frequency Stability: ±4 ppm from 1 min. to 60 min after power on. @25 °C: 1 ppm/hour ±0.5 ppm/1 hour @25 °C, after warmup (with optional TCXO-9) Supply Voltage: Normal: 13.8 VDC ± 15 %, Negative Ground Operating: 8.0-16.0 V, Negative Ground FBA-28 (w/8 “AA” Alkaline Cells): 12.0 V FNB-72 (Ni-Cd Battery Pack): 9.6 V (Option) Current Consumption: Squelched: 250 mA (Approx.) Receive: 450 mA Transmit: 2.0 A Case Size (W x H x D): 135 x 38 x 165 mm (5.31” x 1.5” x 6.50”) Weight (Approx.): 1.17 kg (2.58 lb) w/Alkaline battery, antenna, w/o Microphone Transmitter RF Power Output: 5 W (SSB/CW/FM), 1.5 W (AM Carrier) @13.8 V Modulation Types: SSB: Balanced Modulator AM: Early Stage (Low Level) FM: Variable Reactance FM Maximum Deviation: ±5 kHz (FM-N: ±2.5 kHz) Spurious Radiation: –50 dB (1.8-29.7 MHz) –60 dB (50/144/430 MHz) Carrier Suppression: >40 dB Opp. Sideband Supp.: >50 dB SSB Frequency Response: 400 Hz-2600 Hz (–6 dB) Microphone Impedance: 200-10k Ohms (Nominal: 600 Ohms) Receiver Circuit Type: Double-Conversion Superheterodyne Intermediate Frequencies: 1st: 68.33 MHz (SSB/CW/AM/FM); 10.7 MHz (WFM) 2nd: 455 kHz Sensitivity: SSB/CW AM FM 100 kHz-500 kHz – – – 500 kHz-1.8 MHz – 32 μV – 1.8 MHz-28 MHz 0.25 μV 2 μV – 28 MHz-30 MHz 0.25 μV 2 μV 0.5 μV 50 MHz-54 MHz 0.2 μV 2 μV 0.32 μV 144/430 MHz 0.125 μV – 0.2 μV (IPO, ATT off, SSB/CW/AM = 10 dB S/N, FM = 12 dB SINAD) Squelch Sensitivity: SSB/CW/AM FM 1.8 MHz-28 MHz 2.5 μV – 28 MHz-30 MHz 2.5 μV 0.32 μV 50 MHz-54 MHz 1 μV 0.2 μV 144/430 MHz 0.5 μV 0.16 μV (IPO, ATT off) Image Rejection: HF/50 MHz: 70 dB 144/430 MHz: 60 dB IF Rejection: 60 dB Selectivity (–6/–60 dB): SSB/CW: 2.2 kHz/4.5 kHz AM: 6 kHz/20 kHz FM: 15 kHz/30 kHz FM-N: 9 kHz/25 kHz SSB (optional YF-122S installed): 2.3 kHz/4.7 kHz (–66 dB) CW (optional YF-122C installed): 500 Hz/2.0 kHz AF Output: 1.0 W (8 Ohms, 10% THD or less) AF Output Impedance: 4-16 Ohms Specifications are subject to change without notice, and are guaranteed within amateur bands only. Frequency ranges vary according to transceiver version; check with your dealer.

3 Exploded View & Miscellaneous Parts RA026720B (Lot.36~) RA026720A CHASSIS RA027660A CONNECTOR COVER CP6960001 TOP CASE ASS’Y (W/SP NET) RA0270500 SP HOLDER RA027150B (Lot.49~) RA027150A FRONT PANEL ASSY RA0270300 RUBBER KNOB (ABC) RA0270200 RUBBER KNOB (MODE) RA0270100 RUBBER KNOB (CLAR) RA027040A (Lot.35~) RA0270400 RUBBER KNOB (PWR) VR UNIT RA026960A (Lot.54~) RA0269600 ROTARY KNOB (SEL) RA0269700 MAIN KNOB RA0269800 RUBBER RING RA0269400 ROTARY KNOB (AF) RA0269500 ROTARY KNOB (SQL) RA0276400 (X2 pcs) BELT HOOK RA027090A BATTERY COVER RA027080A BOTTOM CASE RA027530A RELEASE KNOB (A) MAIN UNIT M4090150 SPEAKER RA027540A RELEASE KNOB (B) RA027620B COIL SPRING (2 pcs) RA0276300 HOLDER PLATE PANEL UNIT RA0271700 LCD HOLDER Q7000291 LCD UNIT RA027160A (Lot. 17~) RA0271600 LIGHT GUIDE RA0283600 REFLECTOR SHEET (A) RA0289900 SPONGE RUBBER (BT-A) RA0290000 SPONGE RUBBER (BT-B) RA0293700 SPONGE RUBBER (CASE) (Lot.23~ W/O CE) RA0293600 PAD RA0250800 PAD RA0284300 SPONGE RUBBER (SH-B) RA0284200 (X2 pcs) SPONGE RUBBER (SH-A) PA UNIT / FINAL UNIT RA031630B (Lot.22~) RA031630A (10~) RA0316300 (8~) RA0293500 SPONGE RUBBER (KEY-F) RA0283900 SPONGE RUBBER (SP-B) P1090352 CONNECTOR P1091117A (Lot. 17~) P1091117 CONNECTOR (w/ *1,*2) RA0283800 SPONGE RUBBER (SP-A) Q9000709A ROTARY ENCODER (W/ *3,*4) ˆ ˆ ˆ ˆ ˜ ¨ ¨ ¨ ¨ ¨ ¨ ˆ ˆ ˙ ˙ ¨ ¨ AAB33X001 FBA-28   ˆ `  ¯ ¯ ¯ ¯ ¯ ` ¯ ¯ ¯ ¯ ¯ ¯ ˘ ˘ RA0283700 REFLECTOR SHEET (B) R6054387B SPECIAL NUT ´ *2 *1 *3 *4 No. VXSTD P/N Description Qty. U9900112 TAPTITE SCREW M2X8B 1 U02308001 SEMS SCREW SM3X8 2 U04306002 SEMS SCREW HSM3X6NI 1 U20205007 BINDING HEAD SCREW M2.6X5B 7 U23206001 TAPTITE SCREW M2.6X6 1 U24205001 TAPTITE SCREW M2.6X5 11 U24306002 TAPTITE SCREW M3X6NI 2 U31204007 OVAL HEAD SCREW M2.6X4B 2 U31205007 OVAL HEAD SCREW M2.6X5B 8 U9900012 TAPTITE SCREW M2X4 2 Screw List  ` ´ ˆ ˜ ¯ ˘ ˙ ¨  Description VXSTD P/N VERS. ANTENNA (YHA-63) Q3000174 MIC (MH-31A8J) A06870001 CABLE (E-DC-6) Q9000722 W/O CE DC CABLE (DC 3A 1500MM) T9023003 W/ CE ACCESSORIES

4 Exploded View & Miscellaneous Parts DESCRIPTION VALUE V/W TOL. VS P/N MFR’S DESIG VERS. REF. LOT. SIDE *** MAIN ASSY *** P 0004 WIRE ASSY J1012 to SP T9206744 1- P 0005 WIRE ASSY J1008 to J4002 T9206919 1- P 0006 WIRE ASSY J1003 to J3004 T9206920 1- P 0007 WIRE ASSY BATTERY CASE T9206940 1- P 0007 WIRE ASSY BATTERY CASE T9206932A 3-

5 Block Diagram

6 Block Diagram Note:

7 Circuit Description The FT-817 internal assembly consists of the MAIN Unit, Control ( PANEL) Unit, and the PA Unit. The MAIN Unit contains the receiver front end, PLL IC, and switching circuits, as well as the VCO Unit (local oscillator for transmission and reception). The PANEL Unit contains the CPU and reset circuits, as well as the power circuitry for the LCD. Receive Signal Circuitry High-Frequency Circuit The receive signal enters from the Front (J1001) or Rear (J1002) ANT connector , as selected by relay RL3016 on the PA Unit. Signals between 0.1 and 154 MHz received at the antenna terminal pass through an input low-pass filter composed of L3081, L3082, C3264, and C3265. Received 430 MHz signals, after passing through a high- pass filter composed of L3071, L3076, C3245, and C3254 are passed through low-pass filter composed of L3028, L3032, L3035, C076, C3082, C3088, and C3093, and then are fed through the directional coupler to the UHF T/R switch circuit composed of diode switch D3004/D3035 (both HSU277). The signal then is fed to MAIN Unit via J3002. Received 145 MHz signals, after passing through a high- pass filter composed of L3071, L3075, L3079, C3234, C3245, C3252, and C3260 are passed through low-pass filter composed of L3027, L3031, L3034, C3075, C3081, and C3092, and then are fed through the directional coupler to the VHF T/R switch circuit, composed of diode switch D3003/ D3005 (both HSU277) . The signal then is fed to MAIN Unit via J3002. Received 0.1-54 MHz signals, after passing through the first low-pass filter, are passed through another low-pass filter composed of L3069, L3070, L3074, L3077, C3239, C3242, and C3248, plus LPFs 1-7 (5th or 7th-order Chebyschev type filter) and HPFs 1-7, utilizing seven different sections to create optimized bandpass responses for the various amateur bands at 0.1-54 MHz. The signal then is fed to the 50MHz pre-amplifier (when engaged) and on to the MAIN Unit via J3002. The receive signal then passes through the input attenua- tor (-10dB) which consists of resistors R1001, R1014, and R1015 plus diodes D1003/D1011 (both DAP236U) on the MAIN Unit . Incoming wideband FM (76-108 MHz) signals, after passing through a high-pass filter composed of L3071, L3075, L3079, C3234, C3245, C3252, and C3260 are passed through a low-pass filter composed of L3027, L3031, L3034, C3075, C3081, and C3092 , and through a directional coupler, to the VHF T/R switch circuit, composed of diode switch D3003/D3005 (both HSU277) . Then it is fed to the MAIN Unit via J3002. The signal is delivered to IC Q1025 (CXA1611N) which contains the front-end and discriminator circuits for Wide-FM demodulation. Then the audio signal is passed to analog switch IC Q1049 (BU4066BF). The FT-817 includes four receiver front ends, each optimized for a particular frequency range and mode combi- nation. 1st Mixer Circuit/1st IF Circuit The 1st mixer on the MAIN Unit consists of a quad MES FET, D1047 (GN2011). The 1st local signal (68.430-538.330 MHz) from the PLL Unit is applied to the gates of each FET in the 1st mixer. The resulting output signal (the difference between the local signal and receive signal) passes through a mono- lithic crystal filter (MCF) XF1001 (MF68R, BW:±7.5 kHz) to obtain the 1st IF signal having a center frequency of 68.33 MHz. The signal is then fed to the 2nd mixer circuit on the MAIN Unit after it is amplified by FET Q1051 (BB304C). 2nd Mixer Circuit/2nd IF Circuit The 2nd mixer consists of FETs Q1060 and Q1062 (both 2SK302Y) on the MAIN Unit. The 2nd local signal (67.875 MHz) is amplified by Q1047 (2SC4154E) and is applied to each FET's gate in the 2nd mixer. The signal output from the 2nd mixer passes through a ceramic filter, or optional mechanical filter (U1003), to become the 455-kHz 3rd IF signal. Noise Blanker Circuit A sample of the 2nd IF circuit is amplified by FETs Q1052 and Q1061 (both BB301C) on the MAIN Unit, and then is rectified by D1068 (1SS372). The resulting DC voltage passes through R1343 and R1345, C1360 and C1362, and Q1076 (2SC4154E) to yield an average AGC voltage for

8 Circuit Description controlling the amplification gain of the above FETs. Noise pulses contained in the output from D1075 are detected by Q1074 (2SC4154E) and are used to control the NB Gate. AGC Circuit The AGC circuit consists of D1064 (1SS372), transistor Q1066 (2SC4154E), and associated parts on the MAIN Unit. Output from the AGC circuit is fed back to the RF and IF stages, controlling their gain levels. FM IF Circuit/FM Demodulator Circuit The 2nd IF signal is fed to IC Q1069 (BA4116FV) for FM demodulation. The FM demodulator IC contains a mixer, limiter amplifier, filter amplifier, squelch trigger, and demodulator. The IF input signal is band-limited by ceramic filter CD1002 (CDBC455CX24, BW:±4 kHz), amplified by the limiter amplifier, and demodulated into an audio signal by the demodulator; it then passes through a filter (R1308 and C1293). The signal next passes through a de-emphasis circuit which consists of R1256 and C1286. The squelch circuit selectively amplifies the noise com- ponent of the demodulator output using the filter amplifier inside the FM IC and the active band-pass filter con- sisting of an externally attached resistor and capacitor. This circuit uses a signal detected by D1065 (DA221). SSB/CW Demodulator Circuit The 2nd IF signal is applied to the SSB demodulator Q1055 (SN16913) on the MAIN Unit, which produces audio by applying a carrier signal from the CAR-DDS IC (Q1031). Similarly, the CW signal is demodulated using a carrier signal which is offset by the "Pitch" frequency. The demodulated SSB and CW signals are each stripped of high-frequency components by an active low-pass filter which consists of op-amp IC Q1093-1 (NJM2902V). Then, they enter the VR Unit via J1008. AM Demodulator Circuit The 2nd IF signal from the IF Unit is applied to diode D1060 (BAS316) for AM demodulation . The output from the detector passes through analog switch Q1049 (BU4066BF). Then, it enters the VR Unit via J1008. Audio Amplifier Circuit The demodulated signal that is selected by one of analog switches IC Q1057 (according to the reception mode) passes through the audio amplifier IC Q1094 (NJM2902V), volume control VR4901, and IC Q1070 (TDA7233D) to drive the internal or external speaker with a maximum output of approximately 1.0 Watt. Transmit Signal Circuitry Microphone Amplifier Circuit The audio signal from microphone jack J1014 on the MAIN Unit is amplified by transistor Q1092 (2SC4154E) on the MAIN Unit, and then is applied to electronic volume IC Q1071 (M62364EP), which is controlled via the User Menu (Item #46: SSB MIC). The output (audio signal) from the electronic volume IC is amplified by Q1096 (NJM2902V) and fed to balanced modulator IC Q1087 (SN16913) through the low-pass filter IC Q1096 (NJM2902V). During FM transmission, the audio signal is adjusted via the User Menu (Item# 29 : FM MIC) . The audio signal that has passed through the pre-emphasis circuit (C2201 and R2228 on the MAIN Unit) may be mixed with a tone signal from CPU IC Q4004, and is then amplified and limited by op-amp IC Q1095-4 (NJM2902V) of the IDC circuit. The audio then passes through the splatter filter (sec- ondary active low-pass filter) formed by op-amp IC Q1095-1 (NJM2902V), R1321, and R1322, plus C1344, and is then fed to the frequency-modulator circuit on the MAIN Unit through R1183 and R1477 for setting of the frequency deviation. SSB Modulator Circuit The carrier signal appropriate to the transmitting mode (LSB or USB) is applied from the CAR-DDS Unit to balanced modulator IC Q1087 (SN16913) on the MAIN Unit, and is modulated by microphone audio. The balanced modulator produces the upper and lower side bands and carrier signal. The carrier and audio signal are suppressed and the carrier balance is adjusted by VR1001. As a result, the output signal obtained is a DSB signal with a carrier suppression of 30 dB or more (addi- tional carrier suppression is supplied by the SSB filter). The DSB modulated signal (1st IF signal: 455 kHz) then passes through ceramic filter CF1004 (CFJ455K14) or the optional mechanical filter U1003 on the MAIN Unit, strip- ping residual carrier and the undesired sideband; the signal then passes as an SSB signal through buffer-amplifier Q1040 (BB301C).

9 Circuit Description AM Modulator Circuit As in the SSB modulator circuit, a carrier signal from the CAR-DDS Unit and an audio signal from the microphone are applied to balanced modulator IC Q1087 (SN16913) on the MAIN Unit. The control signal from MODE SW IC Q1021 (BU4094BCFV) on the MAIN Unit causes a voltage labeled "AM 5V" to be sent from transistor Q1079 (2SC4154E). This voltage is applied to IC Q1087 via D1077 (BAS316), caus- ing the balanced modulator to lose balance. The restored carrier signal and modulated signal are then fed to the Tx mixer via ceramic filter CF1004 (CFJ455K14) on the MAIN Unit. Frequency Modulation Circuit The FM circuit uses a voltage controlled crystal oscillator (VCXO) which consists mainly of Q1033 (2SC4400), X1001 on the MAIN-Unit, varactor diode D1056 (HVC362), and T1018. The VCXO has a center frequency of 22.7785MHz. The FM signal is produced by applying a signal from the FM microphone amplifier circuit to varactor diode D1056 and varying the crystal oscillator load capacity in propor- tion to the signal voltage. CW (A1) Signal Generator Circuit When the transmitting mode is CW (A1), the control signal from D-A converter IC Q1077 (M62353GP) on the MAIN Unit creates a "CW 5V" voltage. The voltage is applied to balanced modulator IC Q1087 via D1071, pro- viding a carrier from the balanced modulator for the input to the transmit signal circuit of the MAIN Unit. 1st IF Circuit/1st Mixer Circuit The 455 kHz 1st IF signal from the modulator circuit is band-limited by the MAIN Unit's ceramic (CF1004) or optional mechanical filter U1003 (XF5201 or XF5301) according to the selected mode (CW, SSB, or AM). It is then buffer-amplified by FET Q1040 (BB301C) and fed to 1st mixer IC Q1038 (SN16913). The IF Unit's double balanced mixer IC Q1038 (DBM) is used as the 1st mixer. A local signal (67.875MHz) is produced by tripling the Reference frequency at Q1047 (2SC4154E), and this local signal is fed to the "local" port of the doubly-balanced mixer IC, where it is mixed with the 455 kHz 1st IF signal to produce a 68.33MHz 2nd IF signal. 2nd IF Circuit/2nd Mixer Circuit The 2nd IF signal passes through crystal filter XF1001 and then is fed to the 2nd mixer circuit. The 2nd mixer consists of the MAIN Unit's D1049 (HSB88WS). The 2nd local signal (68.430-538.330MHz) from the PLL Unit is applied to the gates of each FET in the 2nd mixer. High-Frequency Transmit Preamplifier Circuit The transmit signal is passed through a low-pass filter (1.8- 29.7 MHz), a high-pass filter (50-54 MHz), a band-pass filter (144-146 MHz), or a band-pass filter (430-440 MHz) and then is amplified by Q1001 (UPC2710), and passed onward to the PA Unit via J1002. Power Amplifier Circuit The transmit signal from the MAIN Unit arrives at connector J3001 on the PA Unit. The transmit signal (1.8 MHz to 430 MHz) delivered to the PA Unit is amplified by pre-driver Q3001 (2SC3357), driver Q3002 (2SK5296) and final amplifiers Q5401/Q5402 (2SK2975). Low-Pass Filter (LPF) Circuit The transmission signal from the power amplifier circuit is passed through a low-pass filter which consist mainly of RL3001-RL3015, RL3017, and corresponding inductor and capacitor networks. The LPF is a 5th or 7th-order Chebyschev type filter, utilizing nine different sections for the various amateur bands at 1.8 ~ 430 MHz. The low-pass filtered transmission signal is fed to the FRONT ANT connector (J0001) or REAR ANT connector (J0002) through the triplexer and directional coupler. The directional coupler samples a part of the transmission power to detect forward power and reflected power. A DC voltage corresponding to the relative forward/reflected power is produced by D3032/D3033 (both MA716, 1.8 to 54 MHz), D3009/D3017 (both MA716, 144 to 148 MHz), or D3007/D3008 (both MA716, 430 to 450 MHz) , and is used for automatic level control (ALC). ALC Circuit The output from the directional coupler is routed from connector J3004 and applied to the ALC circuit via connector J1003 on the MAIN Unit. The ALC circuit consists of an op-amplifier circuit for amplifying the forward and reflected voltage, a time-con-

10 Circuit Description stant ALC amplifier, and a transmit signal control circuit on the MAIN Unit. The forward voltage from connector J1003 on the MAIN Unit is added with a DC control voltage and is then applied to op-amp IC Q1097 (NJM2902V). The reflected voltage is added with a DC control voltage and is then applied to op-amp IC Q1098 (NJM2904V), In the event of high SWR conditions (SWR of 3:1 or more), transmitter output is reduced and a "High SWR" warn- ing appears, thus protecting the PA Unit from potential damage and alerting the operator to the high SWR situa- tion. The ALC amplifier amplifies the "forward" DC output via transistor Q1019 (2SC4154). This output then passes through a fast-attack, slow-delay RC time-constant circuit which consists of R1097 and C1113 for the input to the Tx signal control circuit on the MAIN Unit. The TX control circuit adjusts the IF amplifier gain via gate 2 of FET Q1007 (BB304C) of the 68.33 MHz IF amplifier circuit to prevent the power output from exceeding the preset level. PLL Frequency Synthesizer The PLL Frequency Synthesizer consists mainly of a master reference oscillator circuit, 2nd local oscillator circuit, plus the PLL IC, CAR-DDS, and REF-DDS units, which digitally synthesize carrier outputs, and a PLL circuit which contains a voltage controlled oscillator (VCO). Master Reference Oscillator Circuit The master reference oscillator uses a crystal oscillator (oscillation frequency: 22.625MHz) composed of Q5001 (2SC4400-4), X5001, TC5001, C5001, R5005, and associated components. The reference oscillator signal passes through buffer amplifier Q5002 (2SC4400-4), C5004, C5007, R5003, R5004, R5007, and is then fed to the MAIN Unit via J5002. CAR-DDS Circuit /REF-DDS Circuit DDS ICs Q1031 (AD9835BRU) and Q2016 (AD9850BAS) each contain a shift register, selector, phase accumulator, and ROM. The reference oscillation frequency (22.625MHz) that is delivered to each of the DDS Units is applied to each DDS IC after amplification by transistors Q1028/Q2020 (both 2SC4400-4). The DDS outputs contain digital amplitude data corresponding to serial frequency data from CPU IC Q4004 of the PANEL Unit. The DDS frequency range is 453.5 ~ 466.5 kHz (cf = 455.0 kHz) for the CAR-DDS, and 7.2-8.0 MHz for the REF DDS. 2nd Local Oscillator Circuit The 2nd L.O. circuit is a Hartley-type overtone oscillator circuit (frequency: 67.875 MHz) composed of Q1047 (2SC4400) on the MAIN Unit. 1st Local Oscillator Circuit VCO output is buffer-amplified by Q2008 (2SC4400), Q2011, Q2014, and Q2016(all 2SC5374) and passes through a low-pass filter. It is then fed to the Tx/Rx frequency mixer circuitry on the MAIN Unit. PLL Circuit The PLL circuit is a frequency mixing type composed of a VCO, mixer, PLL IC, and loop filter. The VCO consists of five circuits (VCO1, VCO2, VCO3, VCO4, and VCO5), with a frequency range of 68.430- 538.330 MHz divided into five bands, allocated to the five VCO circuits. VCO1-VCO5 consist mainly of FETs Q2004, Q2005, and Q2006 (all 2SK210GR), transistors Q2009, Q2010 (both 2SC5374), diodes D2001-D2006 (all HVC362), D2007 (1SV282), D2008 (1SV281), and D2009 (1SV286), and coils T2001-T2003, L2010, and L2011. The VCO switching signal from connector J2002 is used to drive switching transistors Q2001, Q2002, Q2003, Q2012, and Q2013 (all DTC124EU) to switch the source terminal of the oscillator FET. The 68.430-538.330 MHz VCO signal is fed to mixer D1047 (GN2011-Q). The REF-DDS signal (7.2-8.0 MHz) is fed to PLL IC Q2022 (FQ7925) after it passes through a LPF composed of C2064, C2067, C2069, C2071, C2075, L2014, L2015, and L2016 , and buffer amplifier Q2019 (2SC4400-4) . The phase of the reference frequency and that of the signal input to PLL IC are compared, and a signal whose pulse corresponds to the phase difference is produced. The VCO frequency is controlled by a first lag filter which consists of R2057, R2065, R2062, and C2090 and a second- ary lag filter composed of C2085, C2088, and R2053.

VERTEX YAESU FT-817 Service Repair Manual

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