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Tait T889 Manual

Tait T889 Manual

Uhf fm 800-870mhz
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M889-00
T889 Power Amplifier
UHF FM 800-870MHz
Issue 100 October 1995
M889-00-100
Copyright TEL
02/10/95

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Summary of Contents for Tait T889

  • Page 1 M889-00 T889 Power Amplifier UHF FM 800-870MHz Issue 100 October 1995 M889-00-100 Copyright TEL 02/10/95...

  • Page 2: M889

    Phone: 64 3 348-3301 Head Office Fax: 64 3 343-0558 New Zealand Tait Electronics Ltd Singapore 558 Wairakei Road Tait Electronics (Far East) Pte Ltd P.O. Box 1645 4 Leng Kee Road Christchurch SIS Building #05-11A New Zealand Singapore 159088...

  • Page 3: About This Manual

    Technical Information Any enquiries regarding this manual or the equipment it describes should be addressed in the first instance to your nearest approved Tait Dealer or Service Centre. Further technical assistance may be obtained from the Customer Support Group, Radio Infra- structure Division, Tait Electronics Ltd, Christchurch, New Zealand.
  • Page 4 M889-00 Copyright All information contained in this manual is the property of Tait Electronics Ltd. All rights are reserved. This manual may not, in whole or part, be copied, photocopied, reproduced, translated stored or reduced to any electronic medium or machine readable form without prior written permission from Tait Electronics Ltd.
  • Page 5 M889-00 Table Of Contents This manual is divided into seven Sections as listed below. There is a detailed table of contents at the start of each Section. Section Title General Information Circuit Operation Introduction To Servicing Initial Tuning & Adjustment Fault Finding Installation PCB Information...
  • Page 6 M889-00 List Of Effective Pages The total number of pages in this Manual is 64, as listed below. Page Issue Date Page Issue Date 02/10/95 5.10 blank 02/10/95 02/10/95 02/10/95 02/10/95 blank 02/10/95 02/10/95 02/10/95 02/10/95 02/10/95 02/10/95 blank blank 02/10/95 7.1.1 02/10/95...

  • Page 7: Table Of Contents

    General Information M889-00 General Information This section provides a brief description of the T889 PA, along with detailed specifica- tions and a list of variants available. The following topics are covered in this section. Section Title Page Introduction Specifications 1.2.1 Introduction 1.2.2...

  • Page 8: General Information

    General Information M889-00 02/10/95 Copyright TEL...

  • Page 9: Introduction

    RF current. Extensive use is also made of the latest surface mount technology. Forced air cooling for the heatsink is provided on the T889 by a fan, which is activated whenever the transmitter is keyed. Thermal sensors will also activate the fan automati- cally if the internal temperature reaches an unacceptable level.

  • Page 10: Specifications

    EIA specification. However, there are several parameters for which performance according to the CEPT specification is given. Details of test methods and the conditions which apply for Type Approval testing in all countries can be obtained from Tait Electronics Ltd. 1.2.2 General...
  • Page 11 General Information M889-00 Spurious Emissions: Conducted - Transmit .. -36dBm to 1GHz -30dBm to 4GHz - Standby .. -57dBm to 1GHz -47dBm to 4GHz Radiated - Transmit .. -36dBm to 1GHz -30dBm to 4GHz - Standby .. -57dBm to 1GHz -47dBm to 4GHz Dimensions: Height...

  • Page 12: Versions

    General Information M889-00 Versions Version Description 800-870MHz 02/10/95 Copyright TEL...
  • Page 13 Circuit Operation M889-00 Circuit Operation This section provides a basic description of the circuit operation of the T889 PA. The following topics are covered in this section. Section Title Page Introduction RF Circuitry Control Circuitry 2.3.1 Power Control 2.3.2 Driver Power Level 2.3.3...

  • Page 14: Circuit Operation

    Circuit Operation M889-00 02/10/95 Copyright TEL...

  • Page 15: Circuit Operation

    Figure 2.1. RF Circuitry The driver stage of the T889 consists of a two stage transistor amplifier (Q1, Q2) which delivers a minimum of 40W. This signal is split via three 3dB couplers (L13, L14 & L15) and used to drive the four final amplifiers (Q3, Q4, Q5 & Q6). These outputs are recom- bined by L40, L41 &...

  • Page 16: Control Circuitry

    Circuit Operation M889-00 Control Circuitry Figure 2.2 Control Circuitry Block Diagram 02/10/95 Copyright TEL...

  • Page 17: Power Control

    2.3.2 Driver Power Level The maximum output power of the T889 can be limited by placing a ceiling on the driver output power level using RV69 (accessible through the side cover). For example, if RV69 is set for a maximum output power of 50W, the range of adjustment using RV63 (front panel power adjust) will be 20 to 50W.

  • Page 18: Forward And Reverse Power Metering

    Circuit Operation M889-00 2.3.5 Forward And Reverse Power Metering Forward and reverse power signals from the two IC3 buffers are available for metering purposes. The output currents are adjustable via RV43 (forward power) and RV57 (reverse power). 2.3.6 Fan Control Circuitry Invert 13.8V Filtered...
  • Page 19 Introduction To Servicing M889-00 Introduction To Servicing This section provides some general and advisory information on servicing procedures. The following topics are covered in this section. Section Title Page General 3.1.1 Caution: CMOS Devices 3.1.2 Caution: Aerial Load 3.1.3 Caution: Beryllium Oxide & Power Transistors Mechanical 3.2.1 Pozidriv Recess Head Screws...

  • Page 20: Introduction

    Introduction To Servicing M889-00 02/10/95 Copyright TEL...

  • Page 21: Introduction To Servicing

    New Zealand. When requesting this information, please quote the equipment type number (e.g. T889-10) and serial number. In the case of the service manual quote the Tait Internal Part Number (IPN), e.g. M889-00-100, and for circuit diagrams quote the “Title”, “IPN”...

  • Page 22: Caution: Beryllium Oxide & Power Transistors

    Introduction To Servicing M889-00 3.1.3 Caution: Beryllium Oxide & Power Transistors The RF power transistors in current use all contain some beryllium oxide. This sub- stance, while perfectly harmless in its normal solid form, can become a severe health hazard when it has been reduced to dust. For this reason the RF power transistors should not be broken open, mutilated, filed, machined, or physically damaged in any way that can produce dust particles.

  • Page 23: Mechanical

    3.2.2 UNC Thread Screws All black finish Pozidriv screws used in the T889 are 4-40 UNC thread and cannot be interchanged with M3 screws. Note that different lengths are used in different applica- tions.

  • Page 24: Component Replacement

    Introduction To Servicing M889-00 Component Replacement 3.3.1 Leaded Components Whenever components are removed from or fitted to the PCB, care must be taken to avoid damage to the track. The two satisfactory methods of removing components from PTH PCBs are detailed below. Note: The first method requires the use of a desoldering station, e.g.

  • Page 25: Surface Mount Devices

    Surface mount devices (SMD's) require special storage, handling, removal and replacement techniques. This equipment should be serv- iced only by an approved Tait Dealer or Service Centre equipped with the necessary facilities. Repairs attempted with incorrect equipment or by untrained personnel may result in permanent damage. If in doubt, contact Tait Electronics Ltd or your nearest Tait Branch or Subsidiary.

  • Page 26: To Replace Pa Transistors

    Introduction To Servicing M889-00 To Replace PA Transistors Caution: As the location of certain components in the PA is critical to perform- ance, it is important that any components removed or disturbed are EXACTLY refitted in the same position. Do not solder the tabs before torquing down otherwise the device may Caution: be broken.

  • Page 27: Typical Transistor/Capacitor Spacing (Q1 & Q2 Shown)

    Introduction To Servicing M889-00 Grounding Clips measurement a Figure 3.2 Typical Transistor/Capacitor Spacing (Q1 & Q2 Shown) Copyright TEL 02/10/95...

  • Page 28: To Remove The Pcb From The Heatsink

    3.10 Introduction To Servicing M889-00 To Remove The PCB From The Heatsink Most components are soldered topside only, but in some cases access to the underside of the PCB is necessary. Remove the D-range connector. Disconnect the power feed to the fan. Remove the 13 PCB retaining screws (2 are hidden beneath the harmonic filter shield).

  • Page 29: Initial Tuning & Adjustment

    Initial Tuning & Adjustment M889-00 Initial Tuning & Adjustment The following section describes the initial set-up procedures, including alarm adjust- ment and power meter calibration. The following topics are covered in this section. Section Title Page Initial Connections RF Alignment High Temperature Shutdown Power Level Low Forward Power Alarm High Reverse Power Alarm...
  • Page 30 Initial Tuning & Adjustment M889-00 02/10/95 Copyright TEL...
  • Page 31 Initial Tuning & Adjustment M889-00 Initial Connections Connect the PA to a power supply, an output RF load and a power meter as detailed below: power supply rating >30A RF load >150W. Provide a keyed RF drive at the required frequency. Connect the drive source key line to pin 12 of the external connector.
  • Page 32 Initial Tuning & Adjustment M889-00 High Reverse Power Alarm Set RV63 to the required output power. Connect a known mismatch of the required value to the PA output. Apply RF drive and Tx key. Adjust RV52 (reverse power alarm) so that the front panel high reverse power LED just lights.

  • Page 33: Fault Finding

    If the fault still exists after having progressed through them in a logical manner, contact your nearest authorised Tait Dealer or Service Centre. Further assistance may be obtained from the Customer Support Group, Radio Infrastructure Division, Tait Elec- tronics Ltd, Christchurch, New Zealand.
  • Page 34 Fault Finding M889-00 02/10/95 Copyright TEL...
  • Page 35 M889-00 Visual Checks Remove the cover from the T889 and inspect the PCB for damaged or broken com- ponents, paying particular attention to the surface mounted devices (SMD's). Check for defective solder joints. If repair or replacement is considered necessary, refer to Sections 3.3, 3.4, 3.5 and 3.6.
  • Page 36 Fault Finding M889-00 RF Checks The PA Fault Finding Chart (Section 5.5.1) provides a systematic approach for locating a fault in the RF circuitry. Use this chart in conjunction with Figure 5.1, which shows the locations of the 50Ω input and output test points for RF transistors Q1-Q6. Transistor Input Transmission Line Output Transmission Line...
  • Page 37 Fault Finding M889-00 replace A4 pages 5.5/5.6 with A3 pages 5.5/5.6, file name 88900_5a.100 Copyright TEL 02/10/95...
  • Page 38 Fault Finding M889-00 replace A4 pages 5.5/5.6 with A3 pages 5.5/5.6, file name 88900_5a.100 02/10/95 Copyright TEL...
  • Page 39 Check components in LPF. Are R17 & R17A hot to Check output N-type connector touch when PA keyed? for short or wear. Replace parts as necessary. Is maximum power >90W @ 800-870MHz? Return PA to your local Tait service centre. Copyright TEL 02/10/95...
  • Page 40 Fault Finding M889-00 5.5.2 Power Control RF Power Level Control Check Ensure RV69 is fully clockwise. Check sense voltages from Does output power adjust over directional coupler on IC3 pins 1 & 7. the range 20-100W using RV63? Low Forward Power Alarm Check Use RV63 to adjust output power to 60W.
  • Page 41 Fault Finding M889-00 5.5.3 Fan Control Circuitry Key transmitter. Check Q20 & Q21 collector voltages. Check Q17 & Q18. Does fan run at Check IC3 pin 14 <1V. room temperature? Check Q19. Check Tx-key is low (at ground). Spray "freeze" on R116 or short R113.
  • Page 42 5.10 Fault Finding M889-00 02/10/95 Copyright TEL...
  • Page 43 Fault Finding M889-00 Copyright TEL 02/10/95...
  • Page 44 3. Solder the inner core of the test lead to the raised end of the DC blocking capacitor. 3. Solder the inner cores of the transmission line and test lead together off 4. To test, drive the transistor with approx. 10W over the range 800-870MHz and expect T889 PCB Layout the PCB. a minimum output of 30W.

  • Page 45: Installation

    Installation M889-00 Installation The following section gives a brief description of the basic rack mounting and wiring procedures. The following topics are covered in this section. Section Title Page Rack Mounting Rack Wiring Power Supply Figure Title Page Guide Rails Chassis Connectors Latched Position D-Range Wiring - Rear View...
  • Page 46 Installation M889-00 02/10/95 Copyright TEL...

  • Page 47: Rack Mounting

    M889-00 Rack Mounting The T889 PA is designed for use in a standard 483mm rack frame using the supporting guide rails supplied with the unit (refer to Figure 6.1). The lower guide rail is located in the rack frame with three screws, two at the rear and one at the front.
  • Page 48 Installation M889-00 Stop Top Rail RF Output RF Input D-Range Bottom Rail Figure 6.3 Latched Position 02/10/95 Copyright TEL...

  • Page 49: Power Supply

    Figure 6.4 D-Range Wiring - Rear View Power Supply If a power supply other than an appropriate Tait model is used, ensure that it is capable of providing enough current to drive the T800 system and is also free from excessive ripple or noise.
  • Page 50 Installation M889-00 02/10/95 Copyright TEL...

  • Page 51: Pcb Information

    M889-00 PCB Information This section provides parts lists, a grid reference index, PCB layouts and circuit diagrams for the T889 PA. This section contains the following information. Section Title Page Introduction 7.1.3 T889 PA PCB 220-01326-01 7.2.1 Copyright TEL 02/10/95...
  • Page 52 7.1.2 PCB Information M889-00 02/10/95 Copyright TEL...
  • Page 53 PCB Information 7.1.3 M889-00 Introduction PCB Identification All PCBs are identified by a unique 10 digit number, the last 2 digits of which define the issue status. The issue status starts at 00 and increments through 01, 02, 03, etc. as the PCB is updated. Some issue PCBs never reach full production status and are therefore not included in this manual.
  • Page 54 7.1.4 PCB Information M889-00 the line to indicate where the rest of the circuitry is located. The first digit refers to the sheet number (printed on the bottom right hand corner of the CAD diagram) and the last two characters refer to the location on that sheet of the continuation of the circuit (e.g.
  • Page 55 PCB Information 7.2.1 M889-00 T889 PA PCB This section contains the following information. Section Page 220-01326-01 Parts List 7.2.2 Mechanical & Miscellaneous Parts 7.2.5 Grid Reference Index 7.2.7 PCB Layout - Bottom Side 7.2.9 PCB Layout - Top Side 7.2.10 RF Section Circuit Diagram 7.2.11...
  • Page 56 7.2.2 PCB Information M889-00 T889 Parts List (IPN 220-01326-01) How To Use This Parts List The components listed in this parts list are divided into two main types: those with a circuit reference (e.g. C2, D1, R121, etc) and those without (miscellaneous and mechanical).
  • Page 57 L) RES 1218 PWR CHIP 10E 20% 1W 065-10004-20 BEAD FE SMD CBD 4.6/3/3-4S2 039-05025-00 RES DUMP LOAD 25E 50W TO-220 051-00005-28 COIL TAIT NO 528 HAIRPIN 17MM T550A 039-05025-00 RES DUMP LOAD 25E 50W TO-220 052-08160-55 COIL A/W 5.5T/6.0MM HOR 0.8MM WIRE R17A...
  • Page 58 7.2.4 PCB Information M889-00 Description Description R113 036-15270-00 RES M/F 0805 CHIP 27K 5% R115 036-16470-00 RES M/F 0805 CHIP 470K 5% R116 045-04470-01 RES NTC 4K7 5% 5MM DISC R117 036-15150-00 RES M/F 0805 CHIP 15K 5% R118 036-14390-00 RES M/F 0805 CHIP 3K9 5% R119 036-14820-00...
  • Page 59 PCB Information 7.2.5 M889-00 T889 Mechanical & Miscellaneous Parts (220-01326-01) Description Description 012-04150-01 CAP CER F/THRU 1N5 NO LEAD 318-01011-00 RAIL A2M1872 BOTTOM T377 PA C1-C15 318-01012-00 RAIL A3M1873 TOP T377 PA 051-00006-02 SOLDER SPRING 1.3MM A4M1877 (x6) (LED wire joints)
  • Page 60 7.2.6 PCB Information M889-00 02/10/95 Copyright TEL...
  • Page 61 7.2.7 M889-00 T889 Grid Reference Index (IPN 220-01326-01) How To Use This Grid Reference Index The first digit in the PCB layout reference is a "1" or "2", indicating the top or bottom side layout respectively, and the last two charac- ters give the location of the component on that diagram.
  • Page 62 7.2.8 PCB Information M889-00 Device Circuit Device Circuit Device Circuit Device Circuit 1:U5 2-R7 1:U7 2-N1 1:U5 2-S8 1:T8 2-R3 1:W7 2-P8 1:U6 2-D7 1:W8 2-Q7 1:U6 2-D8 1:W3 2-Q5 1:V9 2-C4 1:W5 2-M0 1:V6 2-C4 1:T7 2-P0 1:S2 2-E3 1:T8 2-Q0 1:U4...
  • Page 63 PCB Information M889-00 7.2.9 T889 PCB Layout Bottom Side 220-01326-01 Copyright TEL 02/10/95...
  • Page 64 PCB Information 7.2.10 M889-00 T889 PCB Layout Top Side 220-01326-01 02/10/95 Copyright TEL...
  • Page 65 PCB Information M889-00 7.2.11 T889 RF Section 220-01326-01 Copyright TEL 02/10/95...
  • Page 66 PCB Information 7.2.12 M889-00 T889 Control Section - 220-01326-01 02/10/95 Copyright TEL...

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