Tait T850 II Series Service Manual
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Tait T850 II Series Service Manual

Tait T850 II Series Service Manual

Base station equipment 400-520mhz
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M850-00
T850 Series II
Base Station Equipment
400-520MHz
Service Manual
Issue 200
October 1998
M850-00-200
Copyright TEL
31/09/98

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Summary of Contents for Tait T850 II Series

  • Page 1 M850-00 T850 Series II Base Station Equipment 400-520MHz Service Manual Issue 200 October 1998 M850-00-200 Copyright TEL 31/09/98...
  • Page 2 Phone: 64 3 348-3301 Fax: 61 7 3865-7990 Fax: 64 3 343-0558 Beijing Singapore Tait Mobile Radio (HK) Ltd Tait Electronics (Far East) Pte Ltd Beijing Representative Office 4 Leng Kee Road Room 812, Tower A SIS Building #05-11A Beijing Bright China...
  • Page 3 You may order as many packages as you require from your local Tait Dealer or Customer Service Organisation. Revision pack- ages are supplied ready-punched for inclusion in your manual. Revision Control Each page in this manual has a date of issue.
  • Page 4 Tait Electronics Ltd. Ordering Tait Service Manuals You can order additional copies of this service manual from your nearest Tait Dealer or Customer Service Organisation. When ordering, make sure you quote the correct Tait product code ("M"...
  • Page 5 M850-00 Table Of Contents This manual is divided into nine parts as listed below, with each part being further sub- divided into sections. There is a detailed table of contents at the start of each part and/ or section. Part Title Introduction To Servicing T855 Receiver...
  • Page 6 M850-00 List Of Effective Pages The total number of pages in this Manual is 440, as listed below. Page Issue Date Page Issue Date 31/09/98 31/09/98 31/09/98 31/09/98 31/09/98 1.10 31/09/98 31/09/98 1.11 31/09/98 31/09/98 1.12 31/09/98 31/09/98 1.13 31/09/98 31/09/98 1.14 31/09/98 (blank)
  • Page 7 M850-00 Page Issue Date Page Issue Date 31/09/98 6.3.16 31/09/98 (blank) 31/09/98 6.3.17 31/09/98 (fold-out) 31/09/98 6.3.18 31/09/98 (fold-out) 31/09/98 6.3.19 31/09/98 (fold-out) 31/09/98 6.3.20 31/09/98 (fold-out) 6.3.21 31/09/98 (fold-out) 31/09/98 31/09/98 6.3.22 31/09/98 (fold-out) 31/09/98 6.3.23 31/09/98 (fold-out) 31/09/98 6.3.24 31/09/98 (fold-out) 5.10...
  • Page 8 M850-00 Page Issue Date Page Issue Date 2.14 31/09/98 (blank) 6.1.2 31/09/98 (blank) 6.1.3 31/09/98 31/09/98 6.1.4 31/09/98 31/09/98 6.1.5 31/09/98 31/09/98 6.1.6 31/09/98 31/09/98 31/09/98 6.2.1 31/09/98 31/09/98 6.2.2 31/09/98 (blank) 31/09/98 6.2.3 31/09/98 31/09/98 6.2.4 31/09/98 31/09/98 6.2.5 31/09/98 3.10 31/09/98...
  • Page 9 M850-00 Page Issue Date Page Issue Date 6.3.16 31/09/98 (fold-out) 3.11 31/09/98 (fold-out) 6.3.17 31/09/98 (fold-out) 3.12 31/09/98 (fold-out) (blank) 6.3.18 31/09/98 (fold-out) 3.13 31/09/98 (fold-out) 6.3.19 31/09/98 (fold-out) 3.14 31/09/98 (fold-out) (blank) 6.3.20 31/09/98 (fold-out) 31/09/98 6.3.21 31/09/98 (fold-out) 6.3.22 31/09/98 (fold-out) 31/09/98 (blank)
  • Page 10 M850-00 Page Issue Date Page Issue Date 5.3.7 31/09/98 (blank) 31/09/98 5.3.8 31/09/98 31/09/98 (blank) 5.3.9 31/09/98 (fold-out) 5.3.10 31/09/98 (fold-out) (blank) 31/09/98 5.3.11 31/09/98 31/09/98 5.3.12 31/09/98 31/09/98 5.3.13 31/09/98 (fold-out) 31/09/98 (blank) 5.3.14 31/09/98 (fold-out) 5.3.15 31/09/98 (fold-out) 31/09/98 5.3.16 31/09/98 (fold-out)
  • Page 11 M850-00 Page Issue Date Page Issue Date 31/09/98 31/09/98 31/09/98 (blank) 31/09/98 31/09/98 31/09/98 31/09/98 (blank) Copyright TEL 31/09/98...
  • Page 12 M850-00 31/09/98 Copyright TEL...

  • Page 13: Table Of Contents

    M850-00 Part A Introduction To Servicing This part of the manual is divided into the sections listed below. These sections provide some general and advisory information on servicing procedures, and a brief history of PGM800Win programming software. Section Title Page General Additional Technical Information Caution: CMOS Devices...
  • Page 14 M850-00 31/09/98 Copyright TEL...

  • Page 15: General

    Philips data books covering CMOS devices, or Motorola CMOS data books, Section 5 'Handling', etc. An anti-static bench kit (refer to Figure 1.2) is available from Tait Electronics Ltd under the following product codes: •...

  • Page 16: Caution: Aerial Load

    A1.2 General M850-00 conductive conductive rubber wrist strap bench mat to building earth (not mains earth) Figure 1.2 Typical Anti-static Bench Set-up Caution: Aerial Load The equipment has been designed to operate safely under a wide range of aerial loading conditions.

  • Page 17: Mechanical

    Mechanical A2.1 M850-00 Mechanical Torx Recess Head Screws Torx recess head screws are becoming the standard screw head type in all T800 Series II equipment, with Pozidriv and Philips recess head screws being used in fewer applica- tions. The Torx recess head has the advantage of improved screwdriver tip location, reducing the chances of screw head damage caused by the driver tip rotating within the recess.

  • Page 18: Pozidriv & Philips Recess Head Screws

    A2.2 Mechanical M850-00 Pozidriv & Philips Recess Head Screws Pozidriv and Philips recess head screws will continue to be used in T800 Series II equip- ment in a few special applications. It is important that you use the correct type and size screwdriver for each screw type to avoid damaging the screw head.

  • Page 19: Disassembly/Reassembly

    Mechanical A2.3 M850-00 Disassembly/Reassembly 2.3.1 Receivers/Exciters/Transmitters To carry out alignment or change option links, you need to remove only the top cover, i.e. the one adjacent to the front panel handle and on the opposite side to the main D-range connector (D-range 1/PL100). You need to remove the bottom cover to: •...
  • Page 20 A2.4 Mechanical M850-00 31/09/98 Copyright TEL...

  • Page 21: Component Replacement

    Component Replacement A3.1 M850-00 Component Replacement Leaded Components Whenever you are doing any work on the PCB that involves removing or fitting compo- nents, you must take care not to damage the copper tracks. The two satisfactory meth- ods of removing components from plated-through hole (PTH) PCBs are detailed below. Note: The first method requires the use of a desoldering station, e.g.

  • Page 22: Surface Mount Devices

    Tait Dealer or Customer Service Organisa- tion equipped with the necessary facilities. Repairs attempted with incorrect equipment or by untrained personnel may result in perma- nent damage. If in doubt, contact your nearest Tait Dealer or Customer Service Organisation. Cased Mica Capacitors...

  • Page 23: Software History

    Software History A4.1 M850-00 Software History 28/06/96 PGM800Win Version 1.0 18/08/97 PGM800Win Version 2.00 PGM800Win V1.0 PGM800Win V1.0 is different in concept from DOS versions of PGM800 in that it is Win- dows based. It also includes many new and improved features over DOS versions of PGM800.
  • Page 24 A4.2 Software History M850-00 • Extra information that is not stored in the radio (but which is still relevant to the radio) can be saved to a file on disk (e.g. note field, auxiliary pin names, etc.). Note: The data files produced by BASEPROG V1.0, all DOS versions of PGM800, and PGM800Win V1.0 are still compatible with PGM800Win V2.00.
  • Page 25 M850-00 Part B T855 Receiver This part of the manual is divided into six sections, as listed below. There is a detailed table of contents at the start of each section. Section Title General Information Circuit Operation Initial Tuning & Adjustment Functional Testing Fault Finding PCB Information...
  • Page 26 M850-00 31/09/98 Copyright TEL...
  • Page 27 T855 General Information B1.1 M850-00 T855 General Information This section provides a brief description of the T855 receiver, along with detailed speci- fications and a list of types available. The following topics are covered in this section. Section Title Page Introduction Specifications 1.2.1...
  • Page 28 B1.2 T855 General Information M850-00 31/09/98 Copyright TEL...

  • Page 29: T855 General Information

    T855 General Information B1.3 M850-00 replace A4 pages B1.3/B1.4 with A3 pages B1.3/B1.4 Copyright TEL 31/09/98...
  • Page 30 B1.4 T855 General Information M850-00 replace A4 pages B1.3/B1.4 with A3 pages B1.3/B1.4 31/09/98 Copyright TEL...

  • Page 31: Introduction

    The front panel controls include gating sensitivity, line level, monitor volume and a monitor mute switch. The T855 has a width of 60mm and occupies a single space in a Tait rack frame, which has the ability to accommodate up to seven standard modules.

  • Page 32: Specifications

    1.2.6 for details of test standards. Details of test methods and the conditions which apply for Type Approval testing in all countries can be obtained from Tait Electronics Ltd. The terms "wide bandwidth", "mid bandwidth" and "narrow bandwidth" used in this and following sections are defined in the following table.

  • Page 33: General

    .. ±1ppm, -20°C to +60°C (see also Section 1.4) Signal Strength Indicator .. -115dBm to -70dBm, 0 to 5V (RSSI optional) at approx. 10dB/V 1. Additional channels may be factory programmed. Contact your nearest Tait Dealer or Customer Service Organisation. Copyright TEL 31/09/98...
  • Page 34 B1.8 T855 General Information M850-00 IF Amplifiers: Frequencies .. 45MHz and 455kHz Bandwidths- Narrow Bandwidth (NB) .. 7.5kHz Mid Bandwidth (MB) .. 12kHz Wide Bandwidth (WB) .. 15kHz Sensitivity (De-emphasised Response): Single Channel .. -117dBm Bandspread (12dB Sinad) .. -115dBm (across switching range) Sensitivity (Flat Response): Single Channel ..

  • Page 35: Audio Section

    T855 General Information B1.9 M850-00 1.2.4 Audio Section 1.2.4.1 General Outputs Available .. line and monitor Frequency Response .. flat or de-emphasised (750µs) (link selectable) Flat Response: Bandwidth .. 67 to 3400Hz Response .. within +1, -2dB of output level at 1kHz De-emphasised Response: Bandwidth...

  • Page 36: Mute Operation

    B1.10 T855 General Information M850-00 1.2.4.3 Mute Operation Systems Available .. noise mute and carrier mute Noise Mute: Operating Range .. 6-20dB sinad Hysteresis .. 1.5 to 6dB Threshold .. adjustable to -105dBm Opening Time .. 20ms Closing Time .. 50ms Carrier Mute (Optional): Operating Range ..

  • Page 37: Dti Cept Recommendation T

    T855 General Information B1.11 M850-00 ETS 300 279 February 1996 Radio equipment and systems; electromagnetic compatibility (EMC) standard for pri- vate land mobile radio (PMR) and ancillary equipment (speech and/or non-speech). 1.2.6.2 DTI CEPT Recommendation T/R-24-01 Annex I: 1988 Technical characteristics and test conditions for radio equipment in the land mobile service intended primarily for analogue speech.

  • Page 38: Product Codes

    The following explanation of T850 Series II product codes is not intended to suggest that any combination of features is necessarily available in any one product. Consult your nearest Tait Dealer or Customer Service Organisation for more information regarding the availability of specific models, types and options.

  • Page 39: Standard Product Range

    Standard Product Range The following table lists the range of standard T855 types (i.e. no options fitted) availa- ble at the time this manual was published. Consult your nearest Tait Dealer or Cus- tomer Service Organisation for more information. Frequency Range (MHz)
  • Page 40 B1.14 T855 General Information M850-00 31/09/98 Copyright TEL...
  • Page 41 T855 Circuit Operation B2.1 M850-00 T855 Circuit Operation This section provides a basic description of the circuit operation of the T855 receiver. Note: Unless otherwise specified, the term "PGM800Win" used in this and follow- ing sections refers to version 2.00 and later of the software. Refer to Section 6 where the parts lists, grid reference index and diagrams will provide detailed information on identifying and locating components and test points on the main PCB.
  • Page 42 B2.2 T855 Circuit Operation M850-00 31/09/98 Copyright TEL...

  • Page 43: T855 Circuit Operation

    T855 Circuit Operation B2.3 M850-00 Introduction Noise Mute Mixer Mixer Limiter Speaker Front 45MHz 455kHz Audio Processor 600Ω Line Detector Synthesised Second Local Local Oscillator Oscillator Carrier Mute 12.8MHz Master Oscillator RSSI Figure 2.1 T855 High Level Block Diagram The T855 receiver consists of a number of distinct stages: •...

  • Page 44: Receiver Front End

    B2.4 T855 Circuit Operation M850-00 Receiver Front End (Refer to the front end, IF section and audio processor circuit diagrams (sheets 4, 3 and 2 respectively) in Section 6.3.) Local Oscillator (From Synthesiser) RF In 400-530MHz 4dB Pad Post 4-Pole Harmonic Helical Helical...

  • Page 45: Mixer

    T855 Circuit Operation B2.5 M850-00 Mixer (Refer to the front end circuit diagram (sheet 4) in Section 6.3 and Figure 2.2.) IC410 is a high level mixer requiring a local oscillator (LO) drive level of +17dBm (nom- inal). The voltage controlled oscillator (VCO) generates a level of +21dBm (typical) and this is fed to the mixer via a 5dB attenuator pad.

  • Page 46: Noise Mute (Squelch)

    B2.6 T855 Circuit Operation M850-00 Noise Mute (Squelch) (Refer to the audio processor and IF section circuit diagrams (sheets 2 and 3 respec- tively) in Section 6.3 and Figure 2.2.) The noise mute operates on the detected noise outside the audio bandwidth. An opera- tional amplifier in IC310 is used as an active band pass filter centred on 70kHz to filter out audio components.

  • Page 47: Audio Processor

    T855 Circuit Operation B2.7 M850-00 Audio Processor (Refer to the audio processor circuit diagram (sheet 2) in Section 6.3.) From RSSI RSSI Output IF Stage (Optional) PL270 Mute Relay Relay PL250 Carrier Mute Gate Output Noise Mute Rx Disable Rx Disable Timer (Optional Pad) PL260...

  • Page 48: Power Supply And Regulators

    B2.8 T855 Circuit Operation M850-00 The audio can also be disabled using the "RX-DISABLE" inputs, pads 225 or 228, having connected the "RX-DISABLE" link between pins 1 & 2 of PL260. An adjustable time delay (RV220) is provided on these lines. In order to disable the audio, either pad must be pulled to 0V (refer to Section 1.4 in Part G).

  • Page 49: Microcontroller

    T855 Circuit Operation B2.9 M850-00 Microcontroller (Refer to the microcontroller circuit diagram (sheet 8) in Section 6.3.) 5V Digital Watchdog Timer Regulator & LVI Reset Watchdog Microcontroller Cavity Channel Select Port 12.8MHz Microcontroller Clock Auxiliary Output Port External Serial Converter Port Audio In CTCSS...

  • Page 50: Synthesised Local Oscillator

    B2.10 T855 Circuit Operation M850-00 2.10 Synthesised Local Oscillator (Refer to the synthesiser circuit diagram (sheet 7) in Section 6.3 and the VCO circuit dia- gram in Part E.) FREQUENCY SYNTHESISER IC VCO PCB Reference Phase Charge Loop Output Divider Detector Pump Filter...

  • Page 51: Vco

    T855 Circuit Operation B2.11 M850-00 2.11 (Refer to the VCO circuit diagram in Part E.) The VCO transistor (Q1) operates in a common emitter, and uses a transmission line res- onator (TL1). The transmission line is used in a two port configuration with varicaps positioned at one end.

  • Page 52: Received Signal Strength Indicator (Rssi)

    B2.12 T855 Circuit Operation M850-00 2.12 Received Signal Strength Indicator (RSSI) (Refer to the T800-04-0000 RSSI PCB circuit diagram in Section 6.2 and the IF section cir- cuit diagram (sheet 3) in Section 6.3.) The RSSI option PCB plugs directly into the main PCB (support circuitry being fitted as standard).
  • Page 53 T855 Initial Tuning & Adjustment B3.1 M850-00 T855 Initial Tuning & Adjustment Caution: This equipment contains CMOS devices which are susceptible to dam- age from static charges. Refer to Section 1.2 in Part A for more infor- mation on anti-static procedures when handling these devices. The following section describes both short and full tuning and adjustment procedures and provides information on: •...
  • Page 54 B3.2 T855 Initial Tuning & Adjustment M850-00 Section Title Page Audio Processor Links 3.5.1 General 3.5.2 Audio Processor Linking Details For CTCSS Synthesiser Alignment 3.10 Alignment Of Receiver Front End And IF 3.10 Gating Delay 3.12 Noise Mute Adjustment 3.12 3.10 Carrier Level Mute 3.12...
  • Page 55 PCB. Refer to Part C in the T800 Series Ancillary Equipment Service Manual (M800-00-101 or later issue) or consult your nearest Tait Dealer or Customer Service Organisation for further details. 1. Use the "Read Module" function in PGM800Win to find out what the default channel is.
  • Page 56 B3.4 T855 Initial Tuning & Adjustment M850-00 Test Equipment Required You will need the following test equipment: • computer with PGM800Win installed • T800 programming kit • module programming interface (e.g. T800-01-0004 - optional) • 13.8V power supply • digital multimeter •...
  • Page 57 T855 Initial Tuning & Adjustment B3.5 M850-00 Short Tuning Procedure Use this procedure only if you want to reprogram the receiver to a frequency outside the 5MHz switching range and do not intend to carry out any other major adjustments or repairs.
  • Page 58 B3.6 T855 Initial Tuning & Adjustment M850-00 Continually decrease the RF level to maintain 12dB sinad. Readjust FL410 and FL420 to give best sinad. With PL210 and PL220 connected for de-emphasised audio response, the receiver sensitivity should be better than -117dBm, assuming that the audio levels are not being overdriven (refer to Section 3.4.5).
  • Page 59 T855 Initial Tuning & Adjustment B3.7 M850-00 3.4.6 CTCSS 3.4.6.1 Decoder Operation Program a CTCSS tone on the set channel using PGM800Win. Set the RF signal generator output to -70dBm. Modulate the generator with: • a 1kHz tone at ±3kHz deviation (±2.4kHz) [±1.5kHz] •...

  • Page 60: Audio Processor Links

    B3.8 T855 Initial Tuning & Adjustment M850-00 3.4.7 RSSI (If Fitted) The T800-04-0000 RSSI is an optional PCB which adds signal strength monitoring and high level mute facilities to the basic receiver. Ensure the T800-04-0000 PCB is fitted in SK320 and SK330 in the IF compartment. Apply an on-channel signal from the RF generator at a level of -100dBm with ±3kHz deviation (±2.4kHz) [±1.5kHz] at 1kHz.

  • Page 61: Audio Processor Linking Details For Ctcss

    T855 Initial Tuning & Adjustment B3.9 M850-00 3.5.2 Audio Processor Linking Details For CTCSS You must connect the audio processor links correctly according to the CTCSS option used, as shown in the table below. CTCSS Option PL230 PL240 standard, no CTCSS 2 - 3 N - P 2 - 3...

  • Page 62: Synthesiser Alignment

    B3.10 T855 Initial Tuning & Adjustment M850-00 Synthesiser Alignment • Ensure that the receiver has been programmed with the required frequencies using the PGM800Win software. • Connect a high impedance voltmeter to the long lead of L1 in the VCO (this meas- ures the synthesiser loop voltage).
  • Page 63 T855 Initial Tuning & Adjustment B3.11 M850-00 Tune L385 for zero beat. Note: If a second oscillator is not available, you can connect a frequency counter to IC710 pin 8 (i.e. after the TCXO buffer) via an oscilloscope probe to measure the TCXO frequency directly (12.8MHz).

  • Page 64: Gating Delay

    B3.12 T855 Initial Tuning & Adjustment M850-00 Gating Delay Two solder links (SL210 & SL220) are provided on the bottom of the PCB to allow three gate delay time options, as shown in the table below. SL210 SL220 Closing Delay linked not linked <50ms*...

  • Page 65: Audio Processor

    T855 Initial Tuning & Adjustment B3.13 M850-00 3.11 Audio Processor 3.11.1 Line Amplifier Output Apply an on-channel signal from the RF generator at a level of -70dBm with ±3kHz deviation (±2.4kHz) [±1.5kHz] at 1kHz. Adjust RV210 (front panel line level) to give an output of +10dBm on the 600 ohm line.

  • Page 66: High Pass Filter

    B3.14 T855 Initial Tuning & Adjustment M850-00 Observe the sinad meter and reduce the RF level until the receiver mute closes. Slowly increase the signal level until the receiver mute just opens and stays open. With PL240 pins 1 & 2 linked (G - H; high pass filter bypassed), check that the sinad is less than 6dB.

  • Page 67: Figure

    T855 Functional Testing B4.1 M850-00 T855 Functional Testing Caution: This equipment contains CMOS devices which are susceptible to dam- age from static charges. Refer to Section 1.2 in Part A for more infor- mation on anti-static procedures when handling these devices. The following test procedures will confirm that the T855 has been tuned and adjusted correctly and is fully operational.
  • Page 68 B4.2 T855 Functional Testing M850-00 31/09/98 Copyright TEL...

  • Page 69: Current Consumption

    T855 Functional Testing B4.3 M850-00 Current Consumption Connect the T855 to a 13.8V power supply. Rotate RV230 (front panel gating sensitivity) anticlockwise until the "Gate" LED is extinguished. Set switch SW201 (front panel monitor mute) to the position. Check that the current in the 13.8V power cable is less than 350mA. Rotate the RV230 clockwise until the "Gate"...

  • Page 70: Audio Distortion

    B4.4 T855 Functional Testing M850-00 Audio Distortion The level of distortion measured at the line output (refer to Figure 1.3 in Part F) gives an indication of the accuracy of the IF alignment. Apply an accurate on-channel signal from the RF generator at a level of -70dBm with ±3kHz deviation (±2.4kHz) [±1.5kHz] at 1kHz.

  • Page 71: De-Emphasised Audio Frequency Response

    T855 Functional Testing B4.5 M850-00 De-emphasised Audio Frequency Response Set RV210 (front panel line level) to provide 0dBm output at 1kHz modulating fre- quency. Sweep the modulating frequency, checking that the line audio response closely follows that shown in Figure 4.1 - the limits should not be exceeded. Wide Bandwidth 25°C 13.8V Ref.

  • Page 72: Noise Mute (If Linked In)

    B4.6 T855 Functional Testing M850-00 Noise Mute (If Linked In) Rotate RV230 (front panel gating sensitivity) fully anticlockwise. Apply an on-channel signal from the RF generator at a level of -110dBm with ±3kHz deviation (±2.4kHz) [±1.5kHz] at 1kHz. Increase the RF level in 1dB steps, checking that the mute opens for an RF input level of approximately -105dBm.

  • Page 73: Carrier Level Mute (Rssi Fitted & Carrier Mute Linked In)

    T855 Functional Testing B4.7 M850-00 Carrier Level Mute (RSSI Fitted & Carrier Mute Linked In) Apply an on-channel signal from the RF generator at a level of -120dBm with ±3kHz deviation (±2.4kHz) [±1.5kHz] at 1kHz. Increase the RF level in 2dB steps and check that the mute opens at an RF level which corresponds with the preset level on RV235 (carrier mute), i.e.
  • Page 74 B4.8 T855 Functional Testing M850-00 31/09/98 Copyright TEL...
  • Page 75 If you still cannot trace the fault after progressing through them in a logical manner, contact your nearest Tait Dealer or Customer Service Organisation. If necessary, you can get additional technical help from Customer Support, Radio Systems Division, Tait Elec- tronics Ltd, Christchurch, New Zealand (full contact details are on page 2).
  • Page 76 B5.2 T855 Fault Finding M850-00 Section Title Page PGM800Win Generated Errors Fault Finding Charts 5.7.1 Microcontroller (IC810) 5.7.1.1 Basic Checks 5.7.1.2 Serial Communication 5.10 5.7.1.3 CTCSS Decode 5.11 5.7.2 Regulator 5.12 5.7.3 Synthesiser 5.13 5.7.4 Noise Mute 5.16 5.7.5 Carrier Mute 5.17 5.7.6 Receiver...
  • Page 77 T855 Fault Finding B5.3 M850-00 Visual Checks Remove the covers from the T855 and inspect the PCB for damaged or broken compo- nents, paying particular attention to the surface mounted devices (SMDs). Check for defective solder joints. If repair or replacement of components is considered necessary, refer to Section 3 of Part A.
  • Page 78 B5.4 T855 Fault Finding M850-00 DC Checks 5.4.1 Power Rails Refer to the test points & options diagrams in Section 6 for test point locations, and to the regulator fault finding chart (Section 5.7.2) for fault diagnosis. Check the 9V (TP602) and 13.8V (TP601) power supply test points in the regulator compartment with a DMM.
  • Page 79 T855 Fault Finding B5.5 M850-00 RF Checks 5.5.1 VCO Frequency Check that the VCO is phase locked (refer to Section 5.4.2). Connect a frequency counter (level +20dBm) to the VCO input to the mixer (IC410). below Monitor the local oscillator frequency and check that it is 45MHz required receive frequency.
  • Page 80 B5.6 T855 Fault Finding M850-00 5.5.3 Oscillator Stability 5.5.3.1 TCXO While maintaining a low level unmodulated RF input to the receiver, loosely cou- ple into the first IF an additional high level signal at 45MHz - you should now hear a constant low frequency beat note. Tap the TCXO with a finger and replace it if the beat note permanently changes.
  • Page 81 T855 Fault Finding B5.7 M850-00 Check that the swept response has a rounded top and no sharp non-linearities (refer to Figure 5.2). Increase the RF level to -50dBm; the trace will now show the shape of the 455kHz ceramic filter (&XF302). Check that the response has no sharp non-linearities.

  • Page 82: Pgm800Win Generated Errors

    B5.8 T855 Fault Finding M850-00 PGM800Win Generated Errors The following errors are those most likely to occur using PGM800Win. Refer to the PGM800Win software user’s manual for a complete list of error messages. Channel Switch Set The (programmed) default channel change was not accepted by the base station because a channel is selected externally.

  • Page 83: Fault Finding Charts

    T855 Fault Finding B5.9 M850-00 Fault Finding Charts Note: The standard test point designations used in this section are as follows: TP601 13.8V TP602 TP603 TP604 5.7.1 Microcontroller (IC810) 5.7.1.1 Basic Checks Is the 12.8MHz clock Check IC740 present on IC810 pin 21 (synthesiser).

  • Page 84: Serial Communication

    B5.10 T855 Fault Finding M850-00 5.7.1.2 Serial Communication Disconnect the Low/floating programming lead. Check the transistor Check pin state. Is IC810 pin 11 high? interface circuitry. (microcontroller) Noise on pin Check the SERIAL-COM and AUDIO-1/2 links. Connect the programming lead and use PGM800Win to read the rack/radio.

  • Page 85: Ctcss Decode

    T855 Fault Finding B5.11 M850-00 5.7.1.3 CTCSS Decode Use PGM800Win to Cannot select a channel select a channel Check serial communications. with a CTCSS tone (See separate flow chart). programmed. Set test equipment to correct No square wave or channel/CTCSS tone. uneven mark/space ratio Check the input filter Check IC830 pin 7.

  • Page 86: Regulator

    B5.12 T855 Fault Finding M850-00 5.7.2 Regulator Check for overheating components & short circuits. Check continuity 13.8V present on from D-range IC630 pin 3? connector pin 9. (D-range 1) 5.3V present on Replace IC630. IC630 pin 1? 9.0V present Check Q620, on TP602? Q630 &...

  • Page 87: Synthesiser

    T855 Fault Finding B5.13 M850-00 5.7.3 Synthesiser Refer to the synthesiser circuit diagram (sheet 7) in Section 6 and the VCO circuit dia- gram in Part E. No VCO RF output. VCO out of lock. 9V present at Check 9V reg. +5V present Check 5V reg.
  • Page 88 B5.14 T855 Fault Finding M850-00 Continued from previous page Replace synthesiser (IC740). Check phase detector output Check programming. pins (IC740 pins 3 & 4). Check serial bus Is reference Are there very narrow pulses when programming Programming and clock present (~50ns) at the reference frequency? i.e.
  • Page 89 T855 Fault Finding B5.15 M850-00 Noisy synth; poor selectivity &/or poor residual FM. VCO phase locked? 3-16V present on Go to B. control line? Check inductors, Correct DC V biasing resistors present on Q1 VCO? & Q1. Loop filter & components around Replace if faulty.

  • Page 90: Noise Mute

    B5.16 T855 Fault Finding M850-00 5.7.4 Noise Mute Ensure PL250 is set for noise mute operation. Apply on channel signal *Modulated by 1kHz signal with @ -117dBm* to receiver. ±3kHz (±2.4kHz) [±1.5kHz] deviation Refer to Audio on receiver fault TP314? finding chart.

  • Page 91: Carrier Mute

    T855 Fault Finding B5.17 M850-00 5.7.5 Carrier Mute Ensure PL250 is set for carrier mute operation, and the RSSI PCB is fitted. Apply on channel signal *Modulated by 1kHz signal with @ -110dBm* to receiver. ±3kHz (±2.4kHz) [±1.5kHz] deviation. Refer to Audio on receiver fault TP314?

  • Page 92: Receiver

    B5.18 T855 Fault Finding M850-00 5.7.6 Receiver Refer to the receiver IF and front end circuit diagrams (sheets 3 & 4) in Section 6. Poor sensitivity: worse than -117dBm. Ensure VCO, RF front end & IF correctly aligned. High audio See Chart B distortion? (below).

  • Page 93: Audio

    T855 Fault Finding B5.19 M850-00 5.7.7 Audio Apply on channel signal *Modulated by 1kHz signal with @ -117dBm* to receiver. ±3kHz (±2.4kHz) [±1.5kHz] deviation. Refer to Audio on receiver fault TP314? finding chart. Audio on Check components IC210 pin 1? around IC210.
  • Page 94 B5.20 T855 Fault Finding M850-00 31/09/98 Copyright TEL...
  • Page 95 T855 PCB Information B6.1.1 M850-00 T855 PCB Information Caution: This equipment contains CMOS devices which are susceptible to damage from static charges. Refer to Section 1.2 in Part A for more information on anti-static procedures when handling these devices. This section provides the following information on the T855 receiver: •...
  • Page 96 B6.1.2 T855 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 97 T855 PCB Information B6.1.3 M850-00 Introduction Product Type Identification You can identify the receiver type by checking the product code printed on a label on the rear of the chassis (product codes are explained in Section 1.3 in this Part of the manual, and Figure 1.1 in Part A shows typical labels).
  • Page 98 Components without circuit references are listed in IPN order. The number in brackets at the end of each entry refers to the Tait internal Change Order document. IPN of new...
  • Page 99 T855 PCB Information B6.1.5 M850-00 Variant Components A variant component is one that has the same circuit reference but different value or specification in different product types. Where two products share the same PCB, the term “variant” is also used to describe components unplaced in one product.
  • Page 100 B6.1.6 T855 PCB Information M850-00 Using CAD Circuit Diagrams Reading a CAD circuit diagram is similar to reading a road map, in that both have an alphanumeric border. The circuit diagrams in this manual use letters to represent the horizontal axis, and num- bers for the vertical axis.
  • Page 101 T800-04-0000 RSSI PCB Information B6.2.1 M850-00 T800-04-0000 RSSI PCB This section contains the following information. Section Page 220-01138-00 Parts List 6.2.3 PCB Layout - Top Side 6.2.5 PCB Layout - Bottom Side 6.2.6 Circuit Diagram 6.2.7 Copyright TEL 31/09/98...
  • Page 102 B6.2.2 T800-04-0000 RSSI PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 103 IPN 220-01138-00 T800-04-0000 RSSI PCB Information B6.2.3 M850-00 T800-04-0000 Parts List (IPN 220-01138-00) 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 104 IPN 220-01138-00 B6.2.4 T800-04-0000 RSSI PCB Information M850-00 Description Description 015-24100-08 CAP CER 0805 CHIP 1N 10% X7R 50V 015-24100-08 CAP CER 0805 CHIP 1N 10% X7R 50V 015-23330-08 CAP CER 0805 CHIP 330P 10% X7R 50V 015-25100-08 CAP CER 0805 CHIP 10N 10% X7R 50V 015-24100-08 CAP CER 0805 CHIP 1N 10% X7R 50V 015-25100-08...
  • Page 105 IPN 220-01138-00 T800-04-0000 RSSI PCB Information B6.2.5 M850-00 T800-04-0000 PCB (IPN 220-01138-00) - Top Side Copyright TEL 31/09/98...
  • Page 106 IPN 220-01138-00 B6.2.6 T800-04-0000 RSSI PCB Information M850-00 T800-04-0000 PCB (IPN 220-01138-00) - Bottom Side 31/09/98 Copyright TEL...
  • Page 107 T855 PCB Information B6.3.1 M850-00 T855 Receiver PCB This section contains the following information. Section Page 220-01396-02 Parts List 6.3.3 Mechanical & Miscellaneous Parts 6.3.10 Mechanical Assembly 6.3.11 Grid Reference Index 6.3.13 PCB Layout - Top Side 6.3.17 PCB Layout - Bottom Side 6.3.18 Test Points &...
  • Page 108 B6.3.2 T855 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 109 (710264). Capacitor parallel with L380 (on top of R328) L380 Changed from Tait coil #621 (IPN 050-00016-21) to #622 (IPN 050-00016-22) 303-11169-03 T800 chassis: replaced by 303-11169-04 New chassis and lid tooling introduced, incorporating mechanical improvements and better RF shielding...
  • Page 110 IPN 220-01396-02 B6.3.4 T855 PCB Information M850-00 Description Description C201 020-08100-04 CAP ELE RA 10M 16V 4X7MM &C324 015-21390-01 CAP CER 0805 3P9+-1/4P NPO 50V &C203 015-25100-08 CAP CER 0805 10N 10% X7R 50V &C324 015-21390-01 CAP CER 0805 3P9+-1/4P NPO 50V &C203 015-25100-08 CAP CER 0805 10N 10% X7R 50V...
  • Page 111 L230 056-00021-02 IND FXD 100UH AX C786 015-06100-08 CAP CER 1206 100N 10% X7R 50V L310 050-00016-22 COIL TAIT NO 622 20-120M C788 015-23120-01 CAP CER 0805 120P 5% NPO 50V L320 050-00016-22 COIL TAIT NO 622 20-120M C791 015-21820-01...
  • Page 112 IPN 220-01396-02 B6.3.6 T855 PCB Information M850-00 Description Description Q660 000-10008-17 S) XSTR SMD BC817-25 NPN SOT23 R285 036-15470-00 RES M/F 0805 47K 5% Q670 000-10008-57 S) XSTR SMD BCW70 PNP SOT23 SS R287 036-15100-00 RES M/F 0805 10K 5% Q750 000-10008-07 S) XSTR SMD BC807 PNP SOT23 AF...
  • Page 113 RES M/F 0805 2K2 5% T210 053-00010-17 XFMR T4030 LINE MATCH POTCORE R825 036-14220-00 RES M/F 0805 2K2 5% T610 050-00016-50 COIL TAIT NO 650 455KHZ R826 036-14220-00 RES M/F 0805 2K2 5% R827 036-14220-00 RES M/F 0805 2K2 5% &XF300A 10 276-00010-58...
  • Page 114 IPN 220-01396-02 B6.3.8 T855 PCB Information M850-00 Description Description &XF301 276-00010-54 FLTR XTAL 45MHZ 7.5KHZ 2POLE &XF301 276-00010-56 FLTR XTAL 45MHZ 14KHZ BW 2 P &XF301 276-00010-54 FLTR XTAL 45MHZ 7.5KHZ 2POLE &XF302 276-00010-14 FLTR CER 455KHZ 15KHZ B/W &XF302 276-00010-76 FLTR CER 455KHZ 12KHZ B/W &XF302...
  • Page 115 IPN 220-01396-02 T855 PCB Information B6.3.9 M850-00 Copyright TEL 31/09/98...
  • Page 116 IPN 220-01396-02 B6.3.10 T855 PCB Information M850-00 T855 Mechanical & Miscellaneous Parts (220-01396-02) Legend Description Legend Description 066-00010-20 SLUG BRASS A4M764 HELIC RESNTR 070-01001-00 15/28 D-RANGE 15 WAY COMPL T800 070-02001-00 LED RED COMPL T800 RX/TX/EX 070-02002-00 LED GREEN COMPL T800 RX/TX/EX 200-00010-04 WIRE T/C 0.7 220-01145-02...
  • Page 117 T855 PCB Information B6.3.11 M850-00 replace A4 pages B6.3.11/B6.3.12 with A3 pages B6.3.11/B6.3.12 Copyright TEL 31/09/98...
  • Page 118 B6.3.12 T855 PCB Information M850-00 replace A4 pages B6.3.11/B6.3.12 with A3 pages B6.3.11/B6.3.12 31/09/98 Copyright TEL...
  • Page 119 IPN 220-01396-02 T855 PCB Information B6.3.13 M850-00 T855 Grid Reference Index (IPN 220-01396-02) 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 120 IPN 220-01396-02 B6.3.14 T855 PCB Information M850-00 Device Circuit Device Circuit Device Circuit Device Circuit D860 1:M2 8-N0 P100 1:Q6 1-R8 Q750 1:G4 7-G3 R287 2:B8 2-F2 D860 1:M2 8-N0 P160 1:P2 1-Q4 Q760 1:G3 7-H3 R288 2:B8 2-F1 D880 1:M2 8-R2 P170...
  • Page 121 IPN 220-01396-02 T855 PCB Information B6.3.15 M850-00 Device Circuit Device Circuit Device Circuit Device Circuit R435 2:M7 4-G6 R808 1:K2 8-B6 R895 1:M2 8-Q1 X310 1:F4 3-N6 R440 2:K8 4-J5 R809 1:K2 8-C6 R897 1:M2 8-Q1 R445 2:H8 4-N4 R810 1:L2 8-D6 R898...
  • Page 122 IPN 220-01396-02 B6.3.16 T855 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 123 M850-00 Part C T856 Transmitter & T857 Exciter This part of the manual is divided into six sections, as listed below. There is a detailed table of contents at the start of each section. Section Title General Information Circuit Operation Initial Tuning &...
  • Page 124 M850-00 31/09/98 Copyright TEL...
  • Page 125 T856/857 General Information C1.1 M850-00 T856/857 General Information This section provides a brief description of the T856 transmitter and T857 exciter, along with detailed specifications and a list of types available. The following topics are covered in this section. Section Title Page Introduction...
  • Page 126 C1.2 T856/857 General Information M850-00 31/09/98 Copyright TEL...
  • Page 127 T856/857 General Information C1.3 M850-00 replace A4 pages C1.3/C1.4 with A3 pages C1.3/C1.4 Copyright TEL 31/09/98...
  • Page 128 C1.4 T856/857 General Information M850-00 replace A4 pages C1.3/C1.4 with A3 pages C1.3/C1.4 31/09/98 Copyright TEL...
  • Page 129 T856/857 General Information C1.5 M850-00 replace A4 pages C1.5/C1.6 with A3 pages C1.5/C1.6 Copyright TEL 31/09/98...
  • Page 130 C1.6 T856/857 General Information M850-00 replace A4 pages C1.5/C1.6 with A3 pages C1.5/C1.6 31/09/98 Copyright TEL...

  • Page 131: Introduction

    This switch turns on the carrier (unmodulated) as an aid to servicing. The T856 and T857 are both 60mm wide and each occupies a single space in a Tait rack frame, which has the ability to accommodate up to seven standard modules.

  • Page 132: Specifications

    Transmit - T856 .. 5.5A (typical) - T857 .. 750mA Standby .. 150mA (typical) Operating Temperature Range .. -20°C to +60°C 1. Additional channels may be factory programmed. Contact your nearest Tait Dealer or Customer Service Organisation. 31/09/98 Copyright TEL...

  • Page 133: Rf Section

    T856/857 General Information C1.9 M850-00 Dimensions: Height .. 183mm Width .. 60mm Length .. 320mm Weight .. 2.1kg Time-Out Timer (optional) .. 0 to 5 minutes adjustable in 10 second steps Tail Timer .. 0 to 5 seconds adjustable in 100ms steps Transmit Key Time ..

  • Page 134: Audio Processor

    .. -70dBc with 25dB isolation & interfering signal of -30dBc (PA with output isolator) T856 Mismatch Capability: Ruggedness .. refer to your nearest Tait Dealer or Customer Service Organisation Stability .. 3:1 VSWR (all phase angles) Radiated Spurious Emissions: Transmit ..

  • Page 135: Modulation Characteristics

    T856/857 General Information C1.11 M850-00 1.2.4.2 Modulation Characteristics Frequency Response .. flat or pre-emphasised (optional) (below limiting) Line And Microphone Inputs: Pre-emphasised Response- Bandwidth .. 300Hz to 3kHz (WB & MB) .. 300Hz to 2.55kHz (NB) Below Limiting .. within +1, -3dB of a 6dB/octave pre-emphasis characteristic Flat Response ..

  • Page 136: Test Standards

    C1.12 T856/857 General Information M850-00 1.2.6 Test Standards Where applicable, this equipment is tested in accordance with the following standards. 1.2.6.1 European Telecommunication Standard ETS 300 086 January 1991 Radio equipment and systems; land mobile service; technical characteristics and test conditions for radio equipment with an internal or external RF connector intended pri- marily for analogue speech.

  • Page 137: Product Codes

    The following explanation of T850 Series II product codes is not intended to suggest that any combination of features is necessarily available in any one product. Consult your nearest Tait Dealer or Customer Service Organisation for more information regarding the availability of specific models, types and options.
  • Page 138 T856 Standard Product Range The following table lists the range of standard T856 types (i.e. no options fitted) availa- ble at the time this manual was published. Consult your nearest Tait Dealer or Cus- tomer Service Organisation for more information.
  • Page 139 The following table lists the range of standard T857 types (i.e. no options fitted and cyclic keying disabled) available at the time this manual was published. Consult your nearest Tait Dealer or Customer Service Organisation for more information. Frequency Range (MHz)
  • Page 140 C1.16 T856/857 General Information M850-00 31/09/98 Copyright TEL...
  • Page 141 T856/857 Circuit Operation C2.1 M850-00 T856/857 Circuit Operation This section provides a basic description of the circuit operation of the T856 transmitter and T857 exciter. Note: Unless otherwise specified, the term "PGM800Win" used in this and follow- ing sections refers to version 2.00 and later of the software. Refer to Section 6 where the parts lists, grid reference index and diagrams will provide detailed information on identifying and locating components and test points on the main PCB.
  • Page 142 C2.2 T856/857 Circuit Operation M850-00 Figure Title Page T856 High Level Block Diagram T857 High Level Block Diagram T856/857 Microcontroller Block Diagram T856/857 Synthesiser Block Diagram T856/857 Two Point Modulation T856/857 Audio Processor Block Diagram T856/857 Power Supply & Regulators Block Diagram 2.10 T856/857 Transmit Timers 2.11...
  • Page 143 T856/857 Circuit Operation C2.3 M850-00 Introduction The individual circuit blocks which make up the T856 and T857 are: • synthesiser • VCO • audio processor • drive amplifier • power amplifier (T856 only) • voltage regulators. Each of these circuit blocks is set in its own shielded compartment, formed as an inte- gral part of the main chassis.
  • Page 144 C2.4 T856/857 Circuit Operation M850-00 Microcontroller (Refer to the microcontroller circuit diagram (sheet 8) in Section 6.2 or 6.3.) 5V Digital Watchdog Regulator Reset Reset Microcontroller Cavity Channel Select Port 12.8MHz Microcontroller Dual Digital Clock Auxiliary Potentiometer Output Port External Converter Serial Port...
  • Page 145 T856/857 Circuit Operation C2.5 M850-00 Synthesised Local Oscillator (Refer to the synthesiser circuit diagram (sheet 7) in Section 6.2 or 6.3 and the VCO cir- cuit diagram in Part E.) FREQUENCY SYNTHESISER IC VCO PCB Modulation 12.8MHz Reference Fixed Reference Phase Charge Loop...
  • Page 146 C2.6 T856/857 Circuit Operation M850-00 2.3.1 Two Point Modulation Frequency modulation occurs by modulating both the VCO input and the synthesiser reference input. This process is called two point modulation and ensures a flat modula- tion response from 67Hz to 3kHz (2.55kHz for narrow bandwidth). The PLL has a fast response time, allowing a Tx key-up time of <30ms.
  • Page 147 T856/857 Circuit Operation C2.7 M850-00 (Refer to the VCO circuit diagram in Part E.) The VCO transistor (Q1) operates in a common emitter configuration, with an LC tank circuit coupled between its gate and drain to provide the feedback necessary for oscilla- tion.
  • Page 148 C2.8 T856/857 Circuit Operation M850-00 Audio Processor (Refer to the audio processor circuit diagram (sheet 2) in Section 6.2 or 6.3.) Carrier Opto-coupler Opto-Key Tx Enable Constant Current Sink Tx Key Link Limiter Microphone Compressor PL215 Pre-amp. Link Output Microphone Inhibit mic.
  • Page 149 T856/857 Circuit Operation C2.9 M850-00 2.5.3 Keying Inputs There are four ways to key the exciter: • pulling the Tx-Key line low (pin 13 on D-range 1 [PL100]) at the rear of the set); • pushing the "Carrier" button on the front panel - this will inhibit all audio; •...
  • Page 150 C2.10 T856/857 Circuit Operation M850-00 Power Supply & Regulator Circuits (Refer to the regulators circuit diagram (sheet 6) in Section 6.2 or 6.3.) Buffer Micro- Power Tx Reg. Tx Enable Switch controller Watchdog µP 13.8V Nom. Timer From Rear D-Range 5V Dig Switching µP...
  • Page 151 T856/857 Circuit Operation C2.11 M850-00 Transmit Timers The transmit tail timer, transmit timeout timer and transmit lockout timer can all be set from PGM800Win. The fields for setting these are found on the system information page. These three timers operate as follows (refer also to Figure 2.8): Timer Function Adjustment...
  • Page 152 C2.12 T856/857 Circuit Operation M850-00 T856 Drive Amplifier & PA (Refer to Figure 2.1 and the exciter and PA circuit diagrams (sheets 3 & 4) in Section 6.2.) The output power of the PA is maintained at a constant level via a power control loop applied to the two-stage, wide band exciter amplifier (Q350, Q355).
  • Page 153 T856/857 Circuit Operation C2.13 M850-00 T857 Exciter Drive Amplifier (Refer to Figure 2.2 and the exciter circuit diagram (sheet 3) in Section 6.3.) A two-stage, wide band amplifier (Q350, Q355) provides an output level of approxi- mately 1W (+30dBm) for an input of 100mW (+20dBm) from the VCO. IC300 pin 1, Q302, and Q303 provide a 9V regulated supply for the exciter.
  • Page 154 C2.14 T856/857 Circuit Operation M850-00 31/09/98 Copyright TEL...
  • Page 155 T856/857 Initial Tuning & Adjustment C3.1 M850-00 T856/857 Initial Tuning & Adjustment Caution: This equipment contains CMOS devices which are susceptible to dam- age from static charges. Refer to Section 1.2 in Part A for more infor- mation on anti-static procedures when handling these devices. The following section describes both short and full tuning and adjustment procedures and provides information on: •...
  • Page 156 C3.2 T856/857 Initial Tuning & Adjustment M850-00 Section Title Page Audio Processor Links 3.5.1 Link Details 3.5.2 Typical Options Synthesiser Alignment PA Alignment (T856 Only) 3.10 Thermal Shutdown (T856 Only) 3.10 Audio Processor 3.11 3.9.1 Two Point Modulation 3.11 3.9.2 Modulator Adjustment 3.11 3.9.3...
  • Page 157 PCB. Refer to Part C in the T800 Series Ancillary Equipment Service Manual (M800-00-101 or later issue) or consult your nearest Tait Dealer or Customer Service Organisation for further details. 1. Use the "Read Module" function in PGM800Win to find out what the default channel is.
  • Page 158 C3.4 T856/857 Initial Tuning & Adjustment M850-00 Test Equipment Required You will need the following test equipment: • computer with PGM800Win installed • T800 programming kit • module programming interface (e.g. T800-01-0004 - optional) • 13.8V power supply • digital multimeter •...
  • Page 159 T856/857 Initial Tuning & Adjustment C3.5 M850-00 Short Tuning Procedure Use this procedure only if you want to reprogram the T856/857 to a frequency outside the 8MHz switching range and do not intend to carry out any other major adjustments or repairs.
  • Page 160 C3.6 T856/857 Initial Tuning & Adjustment M850-00 3.4.4 Two Point Modulation Adjustment Note 1: In this and following sections deviation settings are given first for wide bandwidth sets, followed by settings in brackets for mid bandwidth sets ( ) and narrow bandwidth sets [ ]. Note 2: Reference modulation...
  • Page 161 T856/857 Initial Tuning & Adjustment C3.7 M850-00 Adjust RV210 (line sensitivity) fully clockwise and key the transmitter by earthing the Tx-Key line. Adjust IC220 via PGM800Win “deviation” to set the peak devia- tion to ±4.7kHz (±3.8kHz) [±2.3kHz] (you can use either the mouse or up and down arrow keys).
  • Page 162 C3.8 T856/857 Initial Tuning & Adjustment M850-00 Audio Processor Links 3.5.1 Link Details Use the following table to set up the audio processor to the configuration you require. You should set the audio processor links before carrying out any of the tuning and adjustment procedures.
  • Page 163 T856/857 Initial Tuning & Adjustment C3.9 M850-00 Synthesiser Alignment • Ensure that the T856/857 has been programmed with the required frequencies using PGM800Win software. • Single Channel Select a channel using PGM800Win. Multichannel Select the middle channel via PGM800Win. • Connect a high impedance voltmeter to the long lead of L1 in the VCO (this meas- ures the synthesiser loop voltage).
  • Page 164 C3.10 T856/857 Initial Tuning & Adjustment M850-00 PA Alignment (T856 Only) Check that the exciter is connected to the PA with the coaxial link. Connect an RF power meter to the PA output (use an appropriate attenuator as necessary). Turn RV310 (power control) fully clockwise. Note: Before the following measurement is taken, ensure the heatsink is at ambi- ent temperature (20-25°C).
  • Page 165 T856/857 Initial Tuning & Adjustment C3.11 M850-00 Audio Processor 3.9.1 Two Point Modulation The T856 and T857 utilise two point modulation to obtain a wide audio bandwidth independent of the synthesiser loop filter response. This is achieved by simultaneously frequency modulating the VCO and phase modulating the synthesiser reference fre- quency.
  • Page 166 C3.12 T856/857 Initial Tuning & Adjustment M850-00 3.9.3 Limiter Adjustment Note: If the T856/857 will be used over the whole 8MHz switching range, you must set the deviation for each channel. However, if the module will be used on frequencies that cover only a 1MHz (or less) switching range, you can set the deviation on the middle channel and use this value for all other channels with the “fill”...
  • Page 167 T856/857 Initial Tuning & Adjustment C3.13 M850-00 Check that ±3kHz deviation (±2.4kHz) [±1.5kHz] is still available. Slowly increase the audio input level until the demodulated waveform shows sig- nificant signs of clipping (approximately ±4.5kHz (±3.6kHz) [±2.3kHz] deviation). Adjust RV220 anticlockwise until the demodulated waveform is just clipping (approximately ±4kHz (±3.2kHz) [±2kHz] deviation).
  • Page 168 C3.14 T856/857 Initial Tuning & Adjustment M850-00 3.10 CTCSS Encoder Program a CTCSS tone on the set channel using PGM800Win. Key the T856/857 with the front panel "Carrier" switch. Adjust RV805 (CTCSS level adjust) to give 10% system deviation. Reset the maximum deviation as per Section 3.9.3. 31/09/98 Copyright TEL...
  • Page 169 T856/857 Functional Testing C4.1 M850-00 T856/857 Functional Testing Caution: This equipment contains CMOS devices which are susceptible to dam- age from static charges. Refer to Section 1.2 in Part A for more infor- mation on anti-static procedures when handling these devices. The following test procedures will confirm that the T856/857 has been tuned and adjusted correctly and is fully operational.
  • Page 170 C4.2 T856/857 Functional Testing M850-00 31/09/98 Copyright TEL...
  • Page 171 T856/857 Functional Testing C4.3 M850-00 Current Consumption Connect the T856/857 to a 13.8V power supply. Connect an RF power meter to the T856/857 output socket. Check that the current in the 13.8V power cable is less than 150mA. Key the T856/857 by earthing the Tx-Key line (the carrier "On" LED should light). T856 Only: Adjust RV310 (power control) to obtain 25W output power.
  • Page 172 C4.4 T856/857 Functional Testing M850-00 Timer Function Adjustment Transmit Tail Sets the tail time during which the 0-5 seconds in 100ms transmitter stays keyed after the exter- steps nal key source has been removed. Transmit Timeout Sets the maximum continuous trans- 0-300 seconds in 10 mission time.
  • Page 173 T856/857 Functional Testing C4.5 M850-00 Wide Bandwidth Peak + max. dev. = +1.0kHz @ 1000Hz Peak - max. dev. = -1.0kHz @ 1000Hz Frequency (Hz) Mid Bandwidth The mid bandwidth graph is the same shape as the wide bandwidth graph. The devia- tion figures are as follows: peak + max.
  • Page 174 C4.6 T856/857 Functional Testing M850-00 Wide Bandwidth Peak + max. dev. = +4.9kHz @ 1500Hz Peak - max. dev. = -4.4kHz @ 2500Hz Above limiting (steady-state) Frequency (Hz) Mid Bandwidth The mid bandwidth graph is the same shape as the wide bandwidth graph. The devia- tion figures are as follows: peak + max.
  • Page 175 T856/857 Functional Testing C4.7 M850-00 Audio Level Input Sensitivity • Adjust RV210 (line sensitivity) fully clockwise. • Check that the input sensitivities are better than those specified below: Line Input 600 ohms, ±3kHz (±2.4kHz) [±1.5kHz] deviation at 1kHz: with compressor -50dBm without compressor -30dBm...
  • Page 176 C4.8 T856/857 Functional Testing M850-00 31/09/98 Copyright TEL...
  • Page 177 If you still cannot trace the fault after progressing through them in a logical manner, contact your nearest Tait Dealer or Customer Service Organisation. If necessary, you can get additional technical help from Customer Support, Radio Systems Division, Tait Elec- tronics Ltd, Christchurch, New Zealand (full contact details are on page 2).
  • Page 178 C5.2 T856/857 Fault Finding M850-00 Section Title Page Fault Finding Charts 5.7.1 Microcontroller 5.7.1.1 Basic Checks 5.7.1.2 Serial Communications 5.7.1.3 CTCSS Encode 5.10 5.7.2 Regulator 5.11 5.7.3 Synthesiser 5.12 5.7.4 T856 Drive Amplifier 5.15 5.7.5 T856 PA & Power Control 5.16 5.7.6 T857 Exciter Drive Amplifier...
  • Page 179 T856/857 Fault Finding C5.3 M850-00 Visual Checks Remove the covers from the T856/857 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 Section 3 of Part A.
  • Page 180 C5.4 T856/857 Fault Finding M850-00 DC Checks 5.4.1 Power Rails Refer to the test points and options diagrams in Section 6 for test point locations, and to the regulator fault finding chart (Section 5.7.2) for fault diagnosis. Check the 13.8V (TP601) and 9V (TP602) supplies at their test points in the regula- tor compartment with a DMM.
  • Page 181 T856/857 Fault Finding C5.5 M850-00 RF Checks In-circuit RF levels may be measured with an RF probe on which the earth lead has been shortened to a minimum (i.e. 13mm). Refer to the circuit diagrams for typical levels. Figure 5.1 shows a suitable RF probe circuit.. Coax Probe DC to DVM or...
  • Page 182 C5.6 T856/857 Fault Finding M850-00 Connect the exciter output to a power meter and key the exciter. Check that the output power is 1W ±300mW. Note: If the synthesiser is out of lock, the lock detector (synthesiser IC740 and comparator IC750) will prevent the RF signal from reaching the PA by switching the supply to the exciter amplifier (Q301, IC300, Q302, Q303).
  • Page 183 T856/857 Fault Finding C5.7 M850-00 PGM800Win Generated Errors The following errors are those most likely to occur using PGM800Win. Refer to the PGM800Win software user’s manual for a complete list of error messages. Channel Switch Set The programmed default channel change was not accepted by the base station because a channel is selected externally.
  • Page 184 C5.8 T856/857 Fault Finding M850-00 Fault Finding Charts Note: The standard test point designations used in this section are as follows: TP601 13.8V TP602 TP603 TP604 5.7.1 Microcontroller (IC810) 5.7.1.1 Basic Checks Is the 12.8MHz clock Check IC740 present on IC810 pin 21 (synthesiser).
  • Page 185 T856/857 Fault Finding C5.9 M850-00 5.7.1.2 Serial Communication Disconnect the Low/floating programming lead. Check the transistor Check pin state. Is IC810 pin 11 high? interface circuitry. (microcontroller) Noise on pin Check the SERIAL-COM and AUDIO-1/2 links. Connect the programming lead and use PGM800Win to read the rack/radio.
  • Page 186 C5.10 T856/857 Fault Finding M850-00 5.7.1.3 CTCSS Encode Use PGM800Win to Cannot select a channel select a channel Check serial communications. with a CTCSS tone (See separate flow chart). programmed. No square waves or Check IC810 pins 24, 25 uneven mark/space ratio &...
  • Page 187 T856/857 Fault Finding C5.11 M850-00 5.7.2 Regulator Check for overheating components & short circuits. Check continuity 13.8V present on from pin 9 of IC630 pin 3? D-range 1. 5.3V present on Replace IC630. IC630 pin 1? 9.0V present Check Q630, on TP602? Q620 &...
  • Page 188 C5.12 T856/857 Fault Finding M850-00 5.7.3 Synthesiser Refer to the synthesiser circuit diagram (sheet 7) in Section 6 and the VCO circuit dia- gram in Part E. No VCO RF output. VCO out of lock. 9V present at Check Tx reg., +5V present at Check 5V reg.
  • Page 189 T856/857 Fault Finding C5.13 M850-00 Continued from previous page Check microcontroller Replace synthesiser section (IC810). (IC740). Check phase detector output Check programming. pins (IC740 pins 3 & 4). Check serial bus Is reference Are there very narrow pulses when programming Programming and clock present (~50ns) at the reference frequency?
  • Page 190 C5.14 T856/857 Fault Finding M850-00 Noisy synth; poor residual FM. VCO phase locked? 3-16V present on Go to B. control line? Check inductors, Correct DC V biasing resistors present on Q1 VCO? & Q1. Loop filter & components around Replace if faulty. op.
  • Page 191 T856/857 Fault Finding C5.15 M850-00 5.7.4 T856 Drive Amplifier Key exciter & lock synthesiser. 10.5V on Q350 collector? 10.5V on Q315 11.5V on 10.5V on Q355 collector? IC350 pin 7? collector? Check continuity of power rails 13.8V on & DC paths to IC350 pin 8? Q365 &...
  • Page 192 C5.16 T856/857 Fault Finding M850-00 5.7.5 T856 PA & Power Control Normal operating conditions: Set RV320 Forward power = 4.7V approx. (power adjust) fully clockwise; Reverse power = 0.7V approx. Check Q410, synth. locked; IC350 pin 6 = 2.02V Q420 & circuitry, key Tx.
  • Page 193 T856/857 Fault Finding C5.17 M850-00 5.7.6 T857 Exciter Drive Amplifier Key exciter & lock synthesiser. 9V at Q304 collector? 9V at Q303 Check 0.5V at Q304 base? collector? power rails. 9V at Q305 collector? >4V present on Check IC300. IC300 pin 1? Check Q302 &...
  • Page 194 C5.18 T856/857 Fault Finding M850-00 5.7.7 Audio Processor Key exciter & lock synthesiser. Connect 1kHz audio to external CTCSS input. Does exciter Audio output at Check audio path to modulate? IC260 pin 8? VCO control line. Check alignment Audio output at Check buffer IC260 of modulators.
  • Page 195 T856/857 Fault Finding C5.19 M850-00 To Replace The T856 PA Transistors (Q410 & Q420) Caution: Failure to comply with the following procedure can result in failure of the device due to poor heatsinking, or worse, can endanger the health of the assembler if the beryllium oxide die carrier is smashed during assembly.
  • Page 196 C5.20 T856/857 Fault Finding M850-00 Q410 Only: Unscrew the transistor stud nut and remove the device. Remove any excess solder from the PCB pads with solder wick. Trim the tabs of the replacement transistor so that the device sits neatly on the PCB pads provided.
  • Page 197 T856/857 PCB Information C6.1.1 M850-00 T856/857 PCB Information Caution: This equipment contains CMOS devices which are susceptible to damage from static charges. Refer to Section 1.2 in Part A for more information on anti-static procedures when handling these devices. This section provides the following information on the T856 transmitter and T857 exciter: •...
  • Page 198 C6.1.2 T856/857 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 199 T856/857 PCB Information C6.1.3 M850-00 Introduction Product Type Identification You can identify the transmitter or exciter type by checking the product code printed on a label on the rear of the chassis (product codes are explained in Section 1.3 in this Part of the manual, and Fig- ure 1.1 in Part A shows typical labels).
  • Page 200 Components without circuit references are listed in IPN order. The number in brackets at the end of each entry refers to the Tait internal Change Order document. IPN of new...
  • Page 201 T856/857 PCB Information C6.1.5 M850-00 Variant Components A variant component is one that has the same circuit reference but different value or specification in different product types. Where two products share the same PCB, the term “variant” is also used to describe components unplaced in one product.
  • Page 202 C6.1.6 T856/857 PCB Information M850-00 Using CAD Circuit Diagrams Reading a CAD circuit diagram is similar to reading a road map, in that both have an alphanumeric border. The circuit diagrams in this manual use letters to represent the horizontal axis, and num- bers for the vertical axis.
  • Page 203 T856 PCB Information C6.2.1 M850-00 T856 Transmitter PCB This section contains the following information. Section Page 220-01397-01 Parts List 6.2.3 Mechanical & Miscellaneous Parts 6.2.10 Mechanical Assembly 6.2.11 Grid Reference Index 6.2.13 PCB Layout - Top Side 6.2.17 PCB Layout - Bottom Side 6.2.18 Test Points &...
  • Page 204 C6.2.2 T856 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 205 IPN 220-01397-01 T856 PCB Information C6.2.3 M850-00 T856 Parts List (IPN 220-01397-01) 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 206 IPN 220-01397-01 C6.2.4 T856 PCB Information M850-00 Description Description C328 015-06100-08 CAP CER 1206 100N 10% X7R 50V C329 020-07470-04 CAP ELE RA 4M7 25V 20%8X13 SOL Note: %D205 and %D210 are optional level limiting diodes for C330A 015-06100-08 CAP CER 1206 100N 10% X7R 50V special applications.
  • Page 207 IPN 220-01397-01 T856 PCB Information C6.2.5 M850-00 Description Description #C460 029-02220-02 CAP MICA 5 CASE 22P 5% C741B 015-25100-08 CAP CER 0805 10N 10% X7R 50V #C460 029-02270-02 CAP MICA 5 CASE 27P 5% C742A 015-06100-08 CAP CER 1206 100N 10% X7R 50V #C460 029-02270-02 CAP MICA 5 CASE 27P 5%...
  • Page 208 RES M/F 0805 560E 5% L460 065-00010-04 BEAD FERR F8 4X2X5MM R209 036-15100-00 RES M/F 0805 10K 5% L465 051-00005-53 COIL TAIT NO553 A/W 10MM LINK R210 036-14220-00 RES M/F 0805 2K2 5% L475 051-00005-56 COIL NO556 13MM FRMD COP STRP R212 036-16100-00...
  • Page 209 IPN 220-01397-01 T856 PCB Information C6.2.7 M850-00 Description Description R231 036-15100-00 RES M/F 0805 10K 5% R329 036-14100-00 RES M/F 0805 1K 5% R232 036-16330-00 RES M/F 0805 330K 5% R330 036-12220-00 RES M/F 0805 22E 5% R233 036-16100-00 RES M/F 0805 100K 5% R333 030-03470-10 RES FILM 470E 5% 0.5W 7X2.5...
  • Page 210 IPN 220-01397-01 C6.2.8 T856 PCB Information M850-00 Description Description #R440 030-53470-20 RES FILM AI 470E 5% 0.4W 4X1.6 R725 036-15390-00 RES M/F 0805 39K 5% #R440 030-53470-20 RES FILM AI 470E 5% 0.4W 4X1.6 %R726 036-13100-00 RES M/F 0805 100E 5% #R440 030-53820-20 RES FILM AI 820E 5% 0.4W 4X1.6...
  • Page 211 SK805 240-10000-07 CONN SMD SKT 16W 2R M-MATCH SK810 240-04020-42 SKT 44 PIN SMD PLCC SW101 232-00010-26 SWITCH PUSH SPDT R-ANG PCB MTG T210 053-00010-17 XFMR T4030 LINE MATCH POTCORE T610 050-00016-50 COIL TAIT NO 650 455KHZ Copyright TEL 31/09/98...
  • Page 212 IPN 220-01397-01 C6.2.10 T856 PCB Information M850-00 T856 Mechanical & Miscellaneous Parts (220-01397-01) Legend Description Legend Description 070-01001-00 14/37 D-RANGE 15 WAY COMPL T800 356-00010-05 TAG SOLDER 4MM LONG M6144/4.2 070-02001-00 LED RED COMPL T800 RX/TX/EX 362-00010-23 GASKET SIL TO-220 CLIP MTG. 070-02002-00 LED GREEN COMPL T800 RX/TX/EX 362-00010-33...
  • Page 213 T856 PCB Information C6.2.11 M850-00 replace A4 pages C6.2.11/C6.2.12 with A3 pages C6.2.11/C6.2.12 Copyright TEL 31/09/98...
  • Page 214 C6.2.12 T856 PCB Information M850-00 replace A4 pages C6.2.11/C6.2.12 with A3 pages C6.2.11/C6.2.12 31/09/98 Copyright TEL...
  • Page 215 IPN 220-01397-01 T856 PCB Information C6.2.13 M850-00 T856 Grid Reference Index (IPN 220-01397-01) 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 216 IPN 220-01397-01 C6.2.14 T856 PCB Information M850-00 Device Circuit Device Circuit Device Circuit Device Circuit C769 1:H4 7-M4 IC210 1:C7 2-K2 L410 1:H7 4-D4 Q220 1:B3 2-L7 C770 1:H4 7-N4 IC210 1:C7 2-L1 L415 1:G7 4-D3 Q230 1:A4 2-M8 C772 1:G4 7-M2 IC210...
  • Page 217 IPN 220-01397-01 T856 PCB Information C6.2.15 M850-00 Device Circuit Device Circuit Device Circuit Device Circuit R232 1:B4 2-M5 R329 1:F5 3-P5 R525 1:J5 5-D1 R767 1:H3 7-K2 R233 1:B4 2-M6 R330 1:E8 3-H9 R530 1:J5 5-E1 R769 1:H3 7-K3 R235 1:B4 2-P6 R333...
  • Page 218 IPN 220-01397-01 C6.2.16 T856 PCB Information M850-00 Device Circuit Device Circuit Device Circuit Device Circuit SK200 1:D5 2-F0 SK205 1:B5 2-A5 SK310 1:E6 3-R2 SK410 1:G8 4-A4 SK501 1:G6 5-E7 SK502 1:G6 5-E6 SK503 1:G6 5-E5 SK504 1:G5 5-E4 SK505 1:G5 5-E3 SK513...
  • Page 219 T857 PCB Information C6.3.1 M850-00 T857 Exciter PCB This section contains the following information. Section Page 220-01398-02 Parts List 6.3.3 Mechanical & Miscellaneous Parts 6.3.8 Mechanical Assembly 6.3.9 Grid Reference Index 6.3.11 PCB Layout - Top Side 6.3.15 PCB Layout - Bottom Side 6.3.16 Test Points &...
  • Page 220 C6.3.2 T857 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 221 IPN 220-01398-02 T857 PCB Information C6.3.3 M850-00 T857 Parts List (IPN 220-01398-02) 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 222 IPN 220-01398-02 C6.3.4 T857 PCB Information M850-00 Description Description #C316 015-22330-01 CAP CER 0805 33P 5% NPO 50V #C316 015-22330-01 CAP CER 0805 33P 5% NPO 50V Note: %D205 and %D210 are optional level limiting diodes for #C316 015-22330-01 CAP CER 0805 33P 5% NPO 50V special applications.
  • Page 223 IPN 220-01398-02 T857 PCB Information C6.3.5 M850-00 Description Description C724 014-08220-01 (L)CAP TANT 22UF10V276MSER L305 056-10330-02 (L) IND SMD 330NH C725 014-08220-01 (L)CAP TANT 22UF10V276MSER #L307 052-08130-15 COIL A/W 1.5T/3.0MM HOR 0.8MM C726 015-25100-08 CAP CER 0805 10N 10% X7R 50V #L307 052-08130-15 COIL A/W 1.5T/3.0MM HOR 0.8MM...
  • Page 224 IPN 220-01398-02 C6.3.6 T857 PCB Information M850-00 Description Description R225 036-17100-00 RES M/F 0805 1M 5% R313 036-12220-00 RES M/F 0805 22E 5% R226 036-15100-00 RES M/F 0805 10K 5% R314 036-13470-00 RES M/F 0805 470E 5% R227 036-14220-00 RES M/F 0805 2K2 5% R323 036-14150-00 RES M/F 0805 1K5 5%...
  • Page 225 RES M/F 0805 100E 5% T210 053-00010-17 XFMR T4030 LINE MATCH POTCORE R763 036-13100-00 RES M/F 0805 100E 5% T610 050-00016-50 COIL TAIT NO 650 455KHZ R765 036-13680-00 RES M/F 0805 680E 5% R766 036-14100-00 RES M/F 0805 1K 5% R767 036-13680-00...
  • Page 226 IPN 220-01398-02 C6.3.8 T857 PCB Information M850-00 T857 Mechanical & Miscellaneous Parts (220-01398-02) Legend Description Legend Description 070-01001-00 13/25 D-RANGE 15 WAY COMPL T800 070-02001-00 LED RED COMPL T800 RX/TX/EX 070-02002-00 LED GREEN COMPL T800 RX/TX/EX 206-00010-11 COAX 50 OHM RG316-U PTFE Connects SK310 to SK420.
  • Page 227 T857 PCB Information C6.3.9 M850-00 replace A4 pages C6.3.9/C6.3.10 with A3 pages C6.3.9/C6.3.10 Copyright TEL 31/09/98...
  • Page 228 C6.3.10 T857 PCB Information M850-00 replace A4 pages C6.3.9/C6.3.10 with A3 pages C6.3.9/C6.3.10 31/09/98 Copyright TEL...
  • Page 229 IPN 220-01398-02 T857 PCB Information C6.3.11 M850-00 T857 Grid Reference Index (IPN 220-01398-02) 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 230 IPN 220-01398-02 C6.3.12 T857 PCB Information M850-00 Device Circuit Device Circuit Device Circuit Device Circuit IC230 1:B4 2-G1 P235 1:C1 2-R9 Q820 1:L2 8-D5 R284 1:D7 2-L0 IC240 1:D4 2-F3 P237 1:B7 2-R8 Q830 1:L2 8-D5 R285 1:C8 2-M0 IC250 1:D3 2-E1 P239...
  • Page 231 IPN 220-01398-02 T857 PCB Information C6.3.13 M850-00 Device Circuit Device Circuit Device Circuit Device Circuit R550 1:K5 5-K2 R777 1:H4 7-R2 SK310 1:E8 3-N4 R555 1:K5 5-K1 R780 1:G2 7-P1 SK420 1:M8 1-M8 R560 1:K5 5-M0 R782 1:G3 7-P1 SK501 1:G6 5-D6 R609...
  • Page 232 IPN 220-01398-02 C6.3.14 T857 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 233 M850-00 Part D T858 & T859 Power Amplifiers This part of the manual is divided into five sections, as listed below. There is a detailed table of contents at the start of each section. Section Title General Information Circuit Operation Initial Adjustment Fault Finding PCB Information...
  • Page 234 M850-00 31/09/98 Copyright TEL...
  • Page 235 T858/859 General Information D1.1 M850-00 T858/859 General Information This section provides a brief description of the T858 & T859 power amplifiers, along with detailed specifications and a list of types available. The following topics are covered in this section. Section Title Page Introduction...
  • Page 236 D1.2 T858/859 General Information M850-00 31/09/98 Copyright TEL...
  • Page 237 T858/859 General Information D1.3 M850-00 replace A4 pages D1.3/D1.4 with A3 pages D1.3/D1.4 Copyright TEL 31/09/98...
  • Page 238 D1.4 T858/859 General Information M850-00 replace A4 pages D1.3/D1.4 with A3 pages D1.3/D1.4 31/09/98 Copyright TEL...
  • Page 239 T858/859 General Information D1.5 M850-00 replace A4 pages D1.5/D1.6 with A3 pages D1.5/D1.6 Copyright TEL 31/09/98...
  • Page 240 D1.6 T858/859 General Information M850-00 replace A4 pages D1.5/D1.6 with A3 pages D1.5/D1.6 31/09/98 Copyright TEL...
  • Page 241 The T858 has a width of 60mm and occupies a single space in a Tait rack frame, which has the ability to accommodate up to seven standard modules. The T859 has a width of 120mm and occupies a double space.
  • Page 242 ETS specification. Refer to Section 1.2.3 for details of test stand- ards. 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 243 T858/859 General Information D1.9 M850-00 Maximum Supply Current (T858 @ 50W, T859 @ 100W): Standby .. 50mA Transmit - T858 .. 11A - T859 .. 22A Spurious Emissions: Conducted - Transmit .. -36dBm to 1GHz -30dBm to 4GHz - Standby ..
  • Page 244 D1.10 T858/859 General Information M850-00 ETS 300 279 February 1996 Radio equipment and systems; electromagnetic compatibility (EMC) standard for pri- vate land mobile radio (PMR) and ancillary equipment (speech and/or non-speech). 1.2.3.2 DTI CEPT Recommendation T/R-24-01 Annex I: 1988 Technical characteristics and test conditions for radio equipment in the land mobile service intended primarily for analogue speech.
  • Page 245 The following explanation of T850 Series II product codes is not intended to suggest that any combination of features is necessarily available in any one product. Consult your nearest Tait Dealer or Customer Service Organisation for more information regarding the availability of specific models, types and options.
  • Page 246 The following table lists the range of standard T858 and T859 types (i.e. no options fitted and no cyclic keying) available at the time this manual was published. Consult your nearest Tait Dealer or Customer Service Organisation for more information. Output Power (W)
  • Page 247 T858/859 Circuit Operation D2.1 M850-00 T858/859 Circuit Operation This section provides a basic description of the circuit operation of the T858 and T859 power amplifiers. Refer to Section 5 where the parts lists, grid reference index and diagrams will provide detailed information on identifying and locating components.
  • Page 248 D2.2 T858/859 Circuit Operation M850-00 31/09/98 Copyright TEL...
  • Page 249 T858/859 Circuit Operation D2.3 M850-00 Introduction 0.7-1W 2-3dB 20-30W 35-40W 60-70W T858 8-10W 0.7-1W 40-50W 60-70W 105-120W T859 15-20W 0.7-1.8W 20-35W 35-40W 60-80W T878 Forward Power RF Out Ω Load Reverse Power RF In Ω (T858 & T859 Only) Load Figure 2.1 T858/859 High Level Block Diagram The T858 and T859 comprise a five-stage RF power amplifier, the final two stages of which are combined, and extensive control circuitry.
  • Page 250 D2.4 T858/859 Circuit Operation M850-00 RF Circuitry (Refer to the RF section circuit diagram in Section 5.) CV35 Forward Power RF Out CV51 50Ω Load Power Control Load RF In CV34 Reverse Power 50Ω CV32 CV57 Load (T859 Only) (T858 & T859 Only) Figure 2.2 T858/859 RF Circuitry Block Diagram The driver stage of the T858/859 consists of a three-stage transistor amplifier (Q1, Q3 &...
  • Page 251 T858/859 Circuit Operation D2.5 M850-00 Control Circuitry (Refer to the control section circuit diagram in Section 5.) Drive Level Clamp RV69 (T859 Only) 13.8V 13.8V Filtered Voltage Regulator Supply Supply LED Forward Power Meter Forward Power Alarm Low Forward Power LED RV43 RV48 Switch...
  • Page 252 D2.6 T858/859 Circuit Operation M850-00 2.3.1 Power Control The DC voltages from the directional coupler representing forward and reflected power are buffered by the two voltage followers IC3 pins 1, 2 & 3 and pins 5, 6 & 7. Their out- puts are summed at an integrator (IC1 pins 8, 9 &...
  • Page 253 T858/859 Circuit Operation D2.7 M850-00 2.3.4 Forward And Reverse Power Alarms If forward power drops below, or reverse power rises above, presettable limits, alarms may be triggered. The alarm outputs are open drain configuration and are low under normal conditions (i.e.
  • Page 254 D2.8 T858/859 Circuit Operation M850-00 If the temperature drops below -10°C, Q21 is turned off, preventing either Q19 or Q20 from activating the fan. Fan operation may be summarised as follows: T < -10°C - fan unconditionally turned off -10°C < T < +70°C - fan turned on only when transmitter keyed T >...
  • Page 255 T858/859 Initial Adjustment D3.1 M850-00 T858/859 Initial Adjustment Caution: This equipment contains CMOS devices which are susceptible to dam- age from static charges. Refer to Section 1.2 in Part A for more infor- mation on anti-static procedures when handling these devices. The following section describes the full adjustment procedure to be carried out before operating the T858/859.
  • Page 256 D3.2 T858/859 Initial Adjustment M850-00 31/09/98 Copyright TEL...
  • Page 257 D3.3 M850-00 Test Equipment Required • DC power supply capable of delivering the following at 13.8V: T858 >16A (e.g. Tait T807) T859 >25A (e.g. Tait T808). • Multimeter or DMM (e.g. Fluke 77). • RF power meter (e.g. HP 435 series or Bird Wattmeter).
  • Page 258 D3.4 T858/859 Initial Adjustment M850-00 RF Alignment 3.3.1 Standard Tuning Procedure T859 Only: For sets with serial numbers following 217262, set RV69 (driver power level) fully clockwise. Preset the tuning controls as shown in Figure 3.2. Set RV63 (front panel power control) fully clockwise. Key on the drive source.
  • Page 259 T858/859 Initial Adjustment D3.5 M850-00 3.3.2 Tuning Control Settings After alignment the settings of the tuning controls should approximate those shown in Figure 3.2 520MHz 450MHz 485MHz CV32, CV51, CV57 CV34, CV35 CV8, CV1 Figure 3.2 T858/859 Tuning Control Settings 3.3.3 Tuning For Best Efficiency Retune CV32, CV51 and CV57 towards maximum capacitance to obtain minimum...
  • Page 260 D3.6 T858/859 Initial Adjustment M850-00 Setting The Output Power Caution: If the high temperature shutdown power level has not yet been set or is unknown, check that the unit does not overheat while setting the out- put power. Note 1: Cables and connectors can easily cause a power loss of several watts if either too long or poorly terminated.
  • Page 261 T858/859 Initial Adjustment D3.7 M850-00 T858 High Temperature Shutdown Power Level Note 1: The temperature shutdown circuit is factory set to approximately 130°C and 20W. RV69 and RV74 should not be readjusted if normal operation is required. only Note 2: This Section applies to T858 PAs, and T859 PAs with serial numbers prior to 217262.
  • Page 262 D3.8 T858/859 Initial Adjustment M850-00 Remote Forward Power Meter Calibration If a remote meter is connected, adjust RV43 (forward power meter calibration con- trol) for the remote reading to agree with the RF power meter reading. Remote Reverse Power Meter Calibration If a remote meter is connected, connect a 50 ohm 3dB pad (with the output open circuit) to the PA output.
  • Page 263 T858/859 Initial Adjustment D3.9 M850-00 Example: A VSWR of 3:1 can be simulated by connecting an unterminated 3dB pad to the PA output. This will result in a return loss of 6dB. Note: Remote indication is available at D-range pin 4. Copyright TEL 31/09/98...
  • Page 264 D3.10 T858/859 Initial Adjustment M850-00 31/09/98 Copyright TEL...
  • Page 265 If you still cannot trace the fault after progressing through them in a logical manner, contact your nearest Tait Dealer or Customer Service Organisation. If necessary, you can get additional technical help from Customer Support, Radio Systems Division, Tait Elec- tronics Ltd, Christchurch, New Zealand (full contact details are on page 2).
  • Page 266 D4.2 T858/859 Fault Finding M850-00 31/09/98 Copyright TEL...
  • Page 267 T858/859 Fault Finding D4.3 M850-00 Visual Checks Remove the side cover from the T858/859 and inspect the PCB for damaged or broken components, paying particular attention to the surface mounted devices (SMDs). Also check for defective solder joints. Refer to Section 4.7, Section 4.8 and Section 3 of Part A for more details on repair and replacement of components.

  • Page 268: General

    D4.4 T858/859 Fault Finding M850-00 RF Checks 4.4.1 General You can measure in-circuit RF levels around Q1 and Q3 with an RF probe on which the earth lead has been shortened to a minimum (i.e. 13mm); refer to the PA Fault Finding Charts (Section 4.6.1 or Section 4.6.3 as appropriate).
  • Page 269 T858/859 Fault Finding D4.5 M850-00 replace A4 pages D4.5/D4.6 with A3 pages D4.5/D4.6 Figure 4.1 T858/859 Test Break Point Location Copyright TEL 31/09/98...
  • Page 270 D4.6 T858/859 Fault Finding M850-00 replace A4 pages D4.5/D4.6 with A3 pages D4.5/D4.6 31/09/98 Copyright TEL...

  • Page 271: Voltage Chart

    T858/859 Fault Finding D4.7 M850-00 Voltage Chart Test conditions: • typical DC voltages measured with Fluke 77 DVM • supply voltage 13.8V at socket • transmitter unkeyed • allow ±20% for spread of transistor characteristics. Device Emitter Base Collector 0.0V 0.0V 13.0V 0.0V...

  • Page 272: Fault Finding Charts

    D4.8 T858/859 Fault Finding M850-00 Fault Finding Charts 4.6.1 T858 PA Key exciter. Is input power Repair exciter. to PA >0.7W? Check for shorts on base of Q1, >9.6V RF present chips, input matching components at base of Q1? and input pad. Check for Unelco shorts at base or around chips.

  • Page 273: T858 Power Control

    T858/859 Fault Finding D4.9 M850-00 4.6.2 T858 Power Control Approximate voltages under normal operating conditions: Output Power Measurement forward power at "FWD-PWR" pad (beside IC3) 2.5V RV63/R64 (RV63 wiper) 1.4V 2.1V Check 12V DC present on IC1 pin 14. Does power control work? Check sense voltages from directional coupler.

  • Page 274: T859 Pa

    D4.10 T858/859 Fault Finding M850-00 4.6.3 T859 PA Key exciter. Is input power Repair exciter. to PA >0.7W? Check for shorts on base of Q1, >2.5V RF present chips, input matching components at base of Q1? and input pad. Check for Unelco shorts at base or around chips.

  • Page 275: T859 Power Control

    T858/859 Fault Finding D4.11 M850-00 4.6.4 T859 Power Control Approximate voltages under normal operating conditions: Output Power Measurement forward power at "FWD-PWR" pad (beside IC3) 2.5V RV63/R64 (RV63 wiper) 1.4V 2.1V CAUTION The following voltage checks are all done with RV69 (driver power level) set to maximum.

  • Page 276: T859 Fan Control Circuitry

    D4.12 T858/859 Fault Finding M850-00 4.6.5 T859 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"...
  • Page 277 T858/859 Fault Finding D4.13 M850-00 Replacing RF Power Transistors Caution: Failure to comply with the following procedure can result in failure of the device due to poor heatsinking, or worse, can endanger the health of the assembler if the beryllium oxide die carrier is smashed during assembly.
  • Page 278 D4.14 T858/859 Fault Finding M850-00 Q1/Q3 Only: Unscrew the transistor stud nut and remove the device. In the T859 you will need to remove the fan to access the stud nuts. Remove any excess solder from the PCB pads with solder wick. Trim the tabs of the replacement transistor so that the device sits neatly on the PCB pads provided.

  • Page 279: Removing The Pcb From The Heatsink

    T858/859 Fault Finding D4.15 M850-00 Removing The PCB From The Heatsink Note: This is a lengthy procedure and should be considered only after all other checks have been carried out. There are no components on the bottom of the PCB. Remove the harmonic filter shield lid.
  • Page 280 D4.16 T858/859 Fault Finding M850-00 Caution: Do not operate the PA with the PCB detached as the heatsink is used for earthing and heat dissipation. To replace the PCB, reverse the order of removal, taking care that the wiring is cor- rectly positioned and not 'pinched'.
  • Page 281 T858/859 PCB Information D5.1.1 M850-00 T858/859 PCB Information Caution: This equipment contains CMOS devices which are susceptible to damage from static charges. Refer to Section 1.2 in Part A for more information on anti-static procedures when handling these devices. This section provides the following information on the T858 and T859 power amplifiers: •...
  • Page 282 D5.1.2 T858/859 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 283 T858/859 PCB Information D5.1.3 M850-00 Introduction Product Type Identification You can identify the PA type by checking the product code printed on a label on the rear of the chas- sis/heatsink (product codes are explained in Section 1.3 in this Part of the manual, and Figure 1.1 in Part A shows typical labels).
  • Page 284 Components without circuit references are listed in IPN order. The number in brackets at the end of each entry refers to the Tait internal Change Order document. IPN of new...
  • Page 285 T858/859 PCB Information D5.1.5 M850-00 Variant Components A variant component is one that has the same circuit reference but different value or specification in different product types. Where two products share the same PCB, the term “variant” is also used to describe components unplaced in one product.
  • Page 286 D5.1.6 T858/859 PCB Information M850-00 Using CAD Circuit Diagrams Reading a CAD circuit diagram is similar to reading a road map, in that both have an alphanumeric border. The circuit diagrams in this manual use letters to represent the horizontal axis, and num- bers for the vertical axis.
  • Page 287 T858 PCB Information D5.2.1 M850-00 T858 Power Amplifier PCB This section contains the following information. Section Page 220-01141-01 Parts List 5.2.3 Mechanical & Miscellaneous Parts 5.2.8 Mechanical Assembly 5.2.9 Grid Reference Index 5.2.11 PCB Layout - Bottom Side 5.2.13 PCB Layout - Top Side 5.2.14 RF Section Circuit Diagram 5.2.15...
  • Page 288 D5.2.2 T858 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 289 (Low Band) changed from 1T/3.0mm (052-08330-10) to 1T/4.0mm. To meet rated power (90/10-534). L14, L15 & L23 Inductor Tait No.545 added. To remove heat sources from PCB (89/08-438). L27 & L31 Changed from 1.5T/6.0mm (052-08160-15) to 2.5T/6.0mm. To reduce heating in base ferrite beads (89/10-568).
  • Page 290 IPN 220-01141-01 D5.2.4 T858 PCB Information M850-00 Parts List Amendments - Continued This page is provided for entering future amendments to the Parts List. 31/09/98 Copyright TEL...
  • Page 291 CAP MICA 5MM CASE 33P 5% 065-00010-04 BEAD FERRITE F8 4X2X5MM *C47 029-02270-02 CAP MICA 5MM CASE 27P 5% 051-00005-53 COIL TAIT NO 553 A/W 10MM LINK T858/9 *C47 029-02220-02 CAP MICA 5MM CASE 22P 5% 051-00005-39 COUPLER WIRELINE TAIT COIL DWG NO 539 *C49...
  • Page 292 IPN 220-01141-01 D5.2.6 T858 PCB Information M850-00 Description Description 032-33150-02 RES M/F PWR 150E 5% 1W 8X2.5MM 12MML/S 030-03270-00 RES FILM 270E 5% 0.25W 7X2.5MM 030-03470-00 RES FILM 470E 5% 0.25W 7X2.5MM 032-32390-02 RES M/F PWR 39E 5% 1W 8X2.5MM 12MML/S 030-02180-00 RES FILM 18E 5% 0.25W 7X2.5 030-02120-00...
  • Page 293 IPN 220-01141-01 T858 PCB Information D5.2.7 M850-00 Copyright TEL 31/09/98...
  • Page 294 039-02500-01 DUMMY LOAD 50E 1% 10W TO-220 NIKKOHM - R90, R91 303-50005-00 CONTACT A4M2311 SPRING EARTH 051-00005-39 COUPLER WIRELINE TAIT COIL DWG NO 308-01007-01 HANDLE BASE STATION SERIES II 539 - L19, L39 308-13085-01 HSINK DIECAST T858 50W PA 308-13086-00...
  • Page 295 IPN 220-01141-01 T858 PCB Information D5.2.9 M850-00 replace A4 pages D5.2.9/D5.2.10 with A3 pages D5.2.9/D5.2.10 Copyright TEL 31/09/98...
  • Page 296 IPN 220-01141-01 D5.2.10 T858 PCB Information M850-00 replace A4 pages D5.2.9/D5.2.10 with A3 pages D5.2.9/D5.2.10 31/09/98 Copyright TEL...
  • Page 297 IPN 220-01141-01 T858 PCB Information D5.2.11 M850-00 T858 Grid Reference Index (IPN 220-01141-01) 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 298 IPN 220-01141-01 D5.2.12 T858 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 299 T859 PCB Information D5.3.1 M850-00 T859 Power Amplifier PCB This section contains the following information. Section Page 220-01159-01 Parts List 5.3.3 Mechanical & Miscellaneous Parts 5.3.8 Mechanical Assembly 5.3.9 Grid Reference Index 5.3.11 PCB Layout - Bottom Side 5.3.13 PCB Layout - Top Side 5.3.14 RF Section Circuit Diagram 5.3.15...
  • Page 300 D5.3.2 T859 PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 301 IPN 220-01159-01 T859 PCB Information D5.3.3 M850-00 T859 Parts List (IPN 220-01159-01) 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 302 IPN 220-01159-01 D5.3.4 T859 PCB Information M850-00 Parts List Amendments Changed from coil 1.5T/6.0mm (052-08160-15) to 2.5T/6.0mm (90/01-023). L27 & L31 Changed from coil 1.5T/6.0mm (052-08160-15) to 2.5T/6.0mm (89/10-566). (Hi Band) changed from 33e (030-02330-20) to 68e. To ensure adequate drive power on hi band versions (90/08- 390).
  • Page 303 051-00005-60 IND HAIRPIN 10MM TALL T859 015-24470-08 CAP CER 0805 CHIP 4N7 10% X7R 50V 051-00005-39 COUPLER WIRELINE TAIT COIL DWG NO 539 *C62 015-01390-02 CAP CER HIQ 1210 CHIP 3P9 5% NPO 200V 052-08340-20 COIL A/W 2T/4.0MM SMD 0.8MM WIRE...
  • Page 304 RES M/F 0805 CHIP 15K 5% 056-00021-04 IND FXD 330NH AXIAL R107 036-14390-00 RES M/F 0805 CHIP 3K9 5% 051-00005-53 COIL TAIT NO 553 A/W 10MM LINK T858/9 R108 036-15100-00 RES M/F 0805 CHIP 10K 5% R109 036-14330-00 RES M/F 0805 CHIP 3K3 5%...
  • Page 305 IPN 220-01159-01 T859 PCB Information D5.3.7 M850-00 Copyright TEL 31/09/98...
  • Page 306 039-02500-01 DUMMY LOAD 50E 1% 10W TO-220 NIKKOHM - R89/90/91/92/93/94 316-06651-00 PNL PA NO INP DRV SER II DBL 051-00005-39 COUPLER WIRELINE TAIT COIL DWG NO 316-85018-00 PIN A4M1397 COAX CONDUCTOR 539 - L19 319-01147-00 SHIELD A3M2224 WALL T859 PA...
  • Page 307 IPN 220-01159-01 T859 PCB Information D5.3.9 M850-00 replace A4 pages D5.3.9/D5.3.10 with A3 pages D5.3.9/D5.3.10 Copyright TEL 31/09/98...
  • Page 308 IPN 220-01159-01 D5.3.10 T859 PCB Information M850-00 replace A4 pages D5.3.9/D5.3.10 with A3 pages D5.3.9/D5.3.10 31/09/98 Copyright TEL...
  • Page 309 IPN 220-01159-01 T859 PCB Information D5.3.11 M850-00 T859 Grid Reference Index (IPN 220-01159-01) 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 310 IPN 220-01159-01 D5.3.12 T859 PCB Information M850-00 Device Circuit Device Circuit Device Circuit Device Circuit 1:U8 2-Q3 1:W5 2-D7 1:V5 2-D8 1:V6 2-C4 1:V6 2-C4 1:T6 2-E3 1:W3 2-G7 1:T3 2-J8 1:T4 2-H3 1:N10 1-E5 1:G1 1-M1 1:F1 1-N1 1:P10 1-D5 1:D1 1-P2...
  • Page 311 M850-00 Part E T850 VCO PCB Information This part of the manual provides the parts list, PCB layouts and circuit diagram for the T850 VCO PCB. There is a detailed table of contents at the start of Section 2. Section Title Page Introduction...
  • Page 312 M850-00 31/09/98 Copyright TEL...
  • Page 313 Introduction E1.1 M850-00 Introduction PCB Identification All PCBs are identified by a unique 10 digit “internal part number” (IPN), e.g. 220-12345-00, which is screen printed onto the PCB (usually on the top side), as shown in the example below: The last 2 digits of this number define the issue status, which starts at 00 and increments through 01, 02, 03, etc.
  • Page 314 Components without circuit references are listed in IPN order. The number in brackets at the end of each entry refers to the Tait internal Change Order document. IPN of new...
  • Page 315 T850 VCO PCB Information E2.1 M850-00 T850 VCO PCB This section contains the following information. Section Page 220-01145-02 Parts List PCB Layout - Bottom Side PCB Layout - Top Side Circuit Diagram Copyright TEL 31/09/98...
  • Page 316 E2.2 T850 VCO PCB Information M850-00 31/09/98 Copyright TEL...
  • Page 317 IPN 220-01145-02 T850 VCO PCB Information E2.3 M850-00 T850 VCO Parts List (IPN 220-01145-02) 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 318 RES M/F 0805 CHIP 18E 5% 036-13330-00 RES M/F 0805 CHIP 330E 5% 036-12100-00 RES M/F 0805 CHIP 10E 5% *TL1 051-00005-43 RESNTR TAIT NO 543 480-520MHZ T855/7 *TL1 051-00005-42 RESNTR TAIT NO 542 435-480MHZ T855/7 *TL1 051-00005-41 RESNTR TAIT NO 541 395-440MHZ T855/7...
  • Page 319 IPN 220-01145-02 T850 VCO PCB Information E2.5 M850-00 T850 VCO PCB (IPN 220-01145-02) - Bottom Side Copyright TEL 31/09/98...
  • Page 320 IPN 220-01145-02 E2.6 T850 VCO PCB Information M850-00 T850 VCO PCB (IPN 220-01145-02) - Top Side 31/09/98 Copyright TEL...
  • Page 321 M850-00 Part F Installation This part of the manual is divided into the sections listed below. These sections give a brief description of the basic rack mounting and wiring procedures for the T855 receiver, T856 transmitter, T857 exciter and T858/859 power amplifiers. Section Title Page...
  • Page 322 M850-00 Figure Title Page T800-45-0001 PA Guide Kit T858/859 Chassis Connectors T858/859 PA In Latched Position T858/859 D-Range Wiring - Rear View 31/09/98 Copyright TEL...
  • Page 323 M850-00 Part G System Configurations This part of the manual is divided into the sections listed below. These sections provide some brief information on basic system types and how to configure T850 Series II equip- ment for use in them. Section Title Page...
  • Page 324 M850-00 Figure Title Page Talk Through Repeater Basic Configuration Remote Line Controlled Base Station 4-Wire to 2-Wire Converter Receiver Disable Time vs Tail Time DC Loop Keying With Common Earth Isolated Constant Current Loop Current Detector Isolated Loop Current Switch Typical System 31/09/98 Copyright TEL...

  • Page 325: T855 Link Selectable Features

    T855 Link Selectable Features G1.1 M850-00 T855 Link Selectable Features Flat Or De-emphasised Response The links of PL210 and PL220 may be set to give either a flat or de-emphasised audio frequency response (refer to Section 1.7 for further details). Mute Relay Control A relay with undedicated contacts (RL210) is available in the audio processor circuit block for various switching applications.

  • Page 326: 300Hz High Pass Filter

    G1.2 T855 Link Selectable Features M850-00 300Hz High Pass Filter Link PL240 also allows the insertion of this filter to improve hum and noise perform- ance. Audio Processor Links The tables in this section are the same as those in Section 3.5 in Part B. They have been repeated here for ease of reference.

  • Page 327: Audio Processor Linking Details For Ctcss

    T855 Link Selectable Features G1.3 M850-00 1.7.2 Audio Processor Linking Details For CTCSS You must connect the audio processor links correctly according to the CTCSS option used, as shown in the table below. CTCSS Option PL230 PL240 standard, no CTCSS 2 - 3 N - P 2 - 3...
  • Page 328 G1.4 T855 Link Selectable Features M850-00 31/09/98 Copyright TEL...

  • Page 329: T856/857 Optional Features

    T856/857 Optional Features G2.1 M850-00 T856/857 Optional Features Audio Processor The T856 and T857 come with a number of link selectable features which give added system flexibility. Note: The tables in this section are the same as those in Section 3.5 in Part C. They have been repeated here for ease of reference.

  • Page 330: Typical Options

    G2.2 T856/857 Optional Features M850-00 2.1.2 Typical Options PL205 PL210 PL215 PL220 microphone pre-amp. compressed and pre-emphasised; [3-4] [1-2] [3-4] [3-4] line input pre-emphasised (standard set-up) microphone pre-amp. compressed and pre-emphasised; line input unprocessed line and microphone compressed and pre-emphasised microphone pre-amp.
  • Page 331 T856/857 Optional Features G2.3 M850-00 Local Microphone Use of the local microphone (via the front panel stereo socket) will disable the audio input from the line. The audio switching occurs when the PTT switch is closed. Keying With Option PCBs If an option PCB is fitted, the exciter may be keyed via the TX-ENB-OPT pad in the audio processor.
  • Page 332 G2.4 T856/857 Optional Features M850-00 31/09/98 Copyright TEL...

  • Page 333: Talk Through Repeater

    Talk Through Repeater G3.1 M850-00 Talk Through Repeater In this configuration the receiver directly keys the transmitter when the signal is received. The demodulated audio is fed via 600 ohm lines to the transmitter to modu- late the carrier. The receiver and transmitter operate simultaneously and must therefore be on different frequencies.
  • Page 334 G3.2 Talk Through Repeater M850-00 31/09/98 Copyright TEL...

  • Page 335: Line Controlled Base Without Talk Through

    Line Controlled Base Without Talk Through G4.1 M850-00 Line Controlled Base Without Talk Through General This installation contains a transmitter and receiver which may or may not be on the same frequency, thus simultaneous transmission and reception is not possible. When the transmitter is keyed, the coaxial relay is also energised.

  • Page 336: Transmitter Tail Timer

    G4.2 Line Controlled Base Without Talk Through M850-00 Receiver Transmitter approx. 2µ Hybrid Balance 2-Wire Line Figure 4.3 4-Wire to 2-Wire Converter Transmitter Tail Timer If the transmitter has the tail timer enabled: • the receiver disable timer must be set so that Rx/Dis >...
  • Page 337 DC Line Keying G5.1 M850-00 DC Line Keying Where the transmitter and receiver are separated by only a short distance and DC isola- tion is not required, DC loop keying may be employed. A small DC current (usually less than 10mA) can be fed via the balanced 2-wire line to provide remote control of various functions.
  • Page 338 G5.2 DC Line Keying M850-00 Figure 5.3 Isolated Loop Current Switch Long Line Unit 1 Unit 2 Optional bridge to protect against Isolated polarity reversals Supply (T223 only). Figure 5.4 Typical System 31/09/98 Copyright TEL...
  • Page 339 This Part of the manual features a brief description of the major ancillaries that may be used with T800 Series II equipment. For a comprehensive list of available ancillary equipment, please contact your nearest Tait Dealer or Customer Service Organisation. Section...
  • Page 340 M850-00 31/09/98 Copyright TEL...
  • Page 341 T800 Ancillary Equipment M850-00 T800 Ancillary Equipment Programming Kits T800-01-0000 The T800-01-0000 kit is used for programming T800 Series II base station equipment ™ using a standard IBM (or compatible) PC. The kit comprises the following items: PGM800Win programming software user's manual ™...
  • Page 342 T800 Ancillary Equipment M850-00 General Ancillaries T004-72 RF Coaxial Relay The T004-72 is an RF coaxial relay assembly fitted with three female N-type connectors, and comes complete with a mounting bracket and two coaxial cables terminated in male N-type connectors. It can be used, for example, in base station applications where the receiver and transmitter share the same antenna, in which case it can be driven by the T800 Series II transmitter/exciter relay driver (refer to Section 2.4 in Part G for more information).
  • Page 343 T800 Ancillary Equipment M850-00 T800-04-0000 RSSI The T800-04 RSSI option PCB plugs directly into the main PCB (support circuitry being fitted as standard). It is fitted to the T855, T875 and T885 whenever receiver signal strength monitoring is required, e.g. trunking or voting. Its function is to provide a DC voltage proportional to the signal level at the receiver input.
  • Page 344 T800 Ancillary Equipment M850-00 T818-01-0000 Receiver/Transmitter Monitor The T818-01-0000 (formerly T318-02) is designed to monitor the basic operational func- tions of one T800 receiver and transmitter. The meter and selector switches for monitor- ing the required functions are mounted on the front panel, as is the monitor speaker which is driven by a built-in amplifier.
  • Page 345 T800 Ancillary Equipment M850-00 Paging T800-30-0000 & T800-30-0002 DFSK Modulators The T800-30-0000 (formerly T800-30) and T800-30-0002 (formerly T800-35) are DFSK modulators for T800 Series II transmitters, suitable for POCSAG or similar paging data formats. Analogue transmissions (e.g. tone or speech) are still possible by disabling the data path via a control line.
  • Page 346 T800 Ancillary Equipment M850-00 External Frequency Reference T800-06-0000 External Frequency Reference Kit The T800-06-0000 kit provides an additional D-range plug/PCB assembly which incor- porates a miniature RF connector to carry an externally generated 12.8MHz reference signal into a T800 Series II module. This enables the use of very high stability external reference oscillators for special applications.
  • Page 347 T800 Ancillary Equipment M850-00 Rack Frames T800-22-0000 The T800-22-0000 is a standard 5U high rack frame complete with wiring loom which is designed to accommodate one 25, 50 or 100W base station or repeater. It comes fully assembled with the following items: T800-15-0000 speaker panel with programming port T800-40-0001 blank panel (x2) T800-41-0002 double module guide...
  • Page 348 T800 Ancillary Equipment M850-00 T800-22-0005 The T800-22-0005 is the same as the T800-22-0004, but is supplied packed flat in disas- sembled form for ease of transport. T800-23-0000 Slimline Repeater Mounting Kit The T800-23-0000 Slimline Repeater kit enables one T800 Series II receiver and one T800 Series II transmitter to be mounted horizontally side-by-side in a standard 483mm rack frame.
  • Page 349 T800 Ancillary Equipment M850-00 Rack Frame Guides T800-41-0001 The T800-41-0001 rack frame guide is designed to fit into a T800 Series II rack frame and will accept one T800 Series II module (except for power supplies and power amplifiers which must use their own guides). It is supplied disassembled and comprises a top and bottom rail, a rear panel, two D-range sockets and mounting screws.
  • Page 350 T300 D-range socket boxes and mounting screws. The T800-43-0000 is not compatible with the T800 Series II rack frame backplane PCB. Consult your nearest Tait Dealer or Customer Service Organisation for more details about T300/T1500 Series compatibility with T800 Series II rack frames.
  • Page 351 T800 Ancillary Equipment M850-00 Rack Frame PCBs T800-50-0000 The T800-50-0000 backplane PCB is designed to allow a T800-22-0000 rack frame to be easily configured as either a base station or repeater. The PCB mounts across the rear panel of the T800-41-0002 double module rack frame guide, enabling a T800 Series II receiver and exciter/transmitter to plug directly into the D-range sockets provided on the inner side of the PCB (both D-range 1 and D-range 2 are provided for).
  • Page 352 T800 Ancillary Equipment M850-00 Rack Frame Ancillaries T800-13-0000 Extender Rail The T800-13-0000 extender rail allows a T800 Series II receiver, exciter or transmitter to be operated out of the rack frame with the covers off for tuning purposes. It is fitted with two 15-way D-range connectors.
  • Page 353 T800 Ancillary Equipment M850-00 Front Panels T800-15-0000 Speaker Panel Ω A 60mm speaker panel fitted with a 4 speaker and programming socket. It comes complete with mounting hardware and a cable to connect the programming socket to the backplane PCB. T800-15-0001 Speaker Panel Ω...
  • Page 354 T800 Ancillary Equipment M850-00 Power Supplies T800-23-0010 Mains Power Supply The T800-23-0010 mains power supply is designed to power the T800-23-0000/0001 Slimline Repeaters and mounts on the front panel instead of the options tray. It requires a mains input voltage (auto range) of 85-132/170-264V AC at 47-440Hz. Refer to the T800 Ancillary Equipment Service Manual for more information.
  • Page 355 M850-00 Part I Using T850 Series II Equipment In A Series I Rack Frame This part of the manual describes how to modify T850 Series II equipment for operation in a T800 Series I rack frame. Section Title Page Tools Required T855/856/857 SII - SI Conversion Introduction Method...
  • Page 356 I-II M850-00 31/09/98 Copyright TEL...
  • Page 357 Tools Required I1.1 M850-00 Tools Required Tool Size Allen Head Screwdriver 2mm AF Flat Blade Screwdriver 3mm AF Pozidriv Screwdrivers No. 1 for M3 screws No. 2 for M4 screws Torx Screwdrivers T10 for M3 screws T20 for M4 screws Spanners 1/4”...
  • Page 358 I1.2 Tools Required M850-00 31/09/98 Copyright TEL...
  • Page 359 • T855 - T800-70-0055 • T856 - T800-70-0056 • T857 - T800-70-0057. If not, you should purchase one from your nearest Tait Dealer or Customer Service Organisation before beginning the procedure. It should take approximately 15-20 minutes per module to perform these steps.
  • Page 360 I2.2 T855/856/857 SII - SI Conversion M850-00 Method Step Action Remove the Series II front panel from the module as follows: • remove the volume knob (T855 only); • remove the four screws using a Torx screwdriver; • push the LEDs from the front of the panel to remove them from their grommets.
  • Page 361 T855/856/857 SII - SI Conversion I2.3 M850-00 ensure R160 is placed remove R808 Figure 2.1 T855 Component Changes Copyright TEL 31/09/98...
  • Page 362 I2.4 T855/856/857 SII - SI Conversion M850-00 Step Action If you are modifying a T856, follow these steps (refer to Figure 2.2): • remove R808 (10Ω) converts D-range 1 pin 7 from • remove R160 (10Ω) serial com to audio 1 •...
  • Page 363 T855/856/857 SII - SI Conversion I2.5 M850-00 place %R150 remove R160 PL100 remove R808 remove L314 (T857 only) Figure 2.2 T856/857 Component Changes Copyright TEL 31/09/98...
  • Page 364 I2.6 T855/856/857 SII - SI Conversion M850-00 Step Action Converting the T857 from rear panel RF output to front panel RF out- put. Desolder, unscrew and remove the rear panel N-type connector. Fit the blanking plate over the hole in the chassis from which the N-type connector has been removed.
  • Page 365 T855/856/857 SII - SI Conversion I2.7 M850-00 Remove this spring clip and refit it here. Fit the coax as shown, securing it in the groove in the chassis with the spring clip. Figure 2.3 T857 RF Output Coax Routing Copyright TEL 31/09/98...
  • Page 366 I2.8 T855/856/857 SII - SI Conversion M850-00 31/09/98 Copyright TEL...
  • Page 367 • T858 - T800-70-0058 • T859 - T800-70-0059. If not, you should purchase one from your nearest Tait Dealer or Customer Service Organisation before beginning the procedure. It should take approximately 15-20 minutes per module to perform these steps.
  • Page 368 I3.2 T858/859 SII - SI Conversion M850-00 Method Step Action Remove the Series II front panel from the PA as follows: • remove the four screws using a Torx screwdriver; • push the LEDs from the front of the panel to remove them from their grommets.
  • Page 369 T858/859 SII - SI Conversion I3.3 M850-00 Figure 3.1 T858/859 Front RF Input Coax Routing (T859 Shown) Copyright TEL 31/09/98...
  • Page 370 I3.4 T858/859 SII - SI Conversion M850-00 31/09/98 Copyright TEL...

This manual is also suitable for:

T855T856T857T858T859

Table of Contents