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Tait T830 Series Service Manual

Tait T830 Series Service Manual

Base station equipment
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T830 Series
Base Station Equipment
Service Manual
Issue 100
February 1996
M830-00-100
Copyright TEL
31/01/96

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Summary of Contents for Tait T830 Series

  • Page 1 T830 Series Base Station Equipment Service Manual Issue 100 February 1996 M830-00-100 Copyright TEL 31/01/96...
  • Page 2 Phone: 64 3 348-3301 Fax: 64 3 358-3636 Fax: 64 3 343-0558 Radio Infrastructure Division Singapore 535 Wairakei Road Tait Electronics (Far East) Pte Ltd P.O. Box 1645 4 Leng Kee Road Christchurch SIS Building #05-11A New Zealand Singapore 159088...
  • Page 3 If you return the address card at the front of this manual, you will be notified when revision packages containing new PCB information and/or text are available. You may then order as many packages as you require from your local Tait Company. Revision packages are supplied ready-punched for inclusion in your manual.
  • Page 4 Technical Information Any enquiries regarding this manual or the equipment it describes should be addressed in the first instance to your nearest approved Tait Dealer or Service Centre. Further technical assistance may be obtained from the Customer Support Group, Radio Infra- structure Division, Tait Electronics Ltd, Christchurch, New Zealand.
  • Page 5 Table Of Contents This manual is divided into eight 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 T835 Receiver T836 Transmitter &...
  • Page 6 List Of Effective Pages The total number of pages in this Manual is 296, as listed below. Page Issue Date Page Issue Date 31/01/96 31/01/96 31/01/96 31/01/96 (blank) 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 (blank) 31/01/96 31/01/96 (blank) 31/01/96...
  • Page 7 Page Issue Date Page Issue Date 31/01/96 31/01/96 31/01/96 31/01/96 (blank) 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 5.10 31/01/96 31/01/96 5.11 31/01/96 31/01/96 5.12 31/01/96 31/01/96 5.13 31/01/96 31/01/96 5.14 31/01/96 2.10 31/01/96 6.1.1 31/01/96 31/01/96 6.1.2 31/01/96 (blank) 31/01/96 6.1.3 31/01/96 31/01/96...
  • Page 8 Page Issue Date Page Issue Date 6.2.1 31/01/96 31/01/96 6.2.2 31/01/96 (blank) 6.2.3 31/01/96 31/01/96 6.2.4 31/01/96 31/01/96 (blank) 6.2.5 31/01/96 31/01/96 6.2.6 31/01/96 31/01/96 6.2.7 31/01/96 31/01/96 6.2.8 31/01/96 (blank) 31/01/96 6.2.9 31/01/96 31/01/96 6.2.10 31/01/96 31/01/96 (blank) 6.2.11 31/01/96 6.2.12 31/01/96...
  • Page 9 Page Issue Date Page Issue Date 31/01/96 Part H 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 (blank) 31/01/96 31/01/96 (blank) 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 31/01/96 (blank) 31/01/96 (blank) 31/01/96 31/01/96 31/01/96 31/01/96 (blank) Part F 31/01/96 31/01/96 (blank) 31/01/96 31/01/96 31/01/96...
  • Page 10 31/01/96 Copyright TEL...

  • Page 11: Table Of Contents

    This part of the manual is divided into the sections listed below. These sections provide some general and advisory information on servicing procedures, a brief history of T800 programming software, and a list of Technical Instructions pertaining to T830 Series equipment.
  • Page 12 31/01/96 Copyright TEL...

  • Page 13: General

    General If further information is required about T830 Series equipment or this Manual, it may be obtained from Tait Electronics Ltd or accredited agents. When requesting this informa- tion, please quote the equipment type number (e.g. T835-20) and serial number. In the case of the Service Manual quote the Tait Internal Part Number (IPN), e.g.

  • Page 14: Caution: Aerial Load

    Caution: Aerial Load The equipment has been designed to operate safely under a wide range of aerial loading conditions. However, it is strongly recommended that the transmitter should not be operated in the absence of a suitable load. Failure to observe this warning may result in damage to the transmitter output power stage.

  • Page 15: Mechanical

    Mechanical Pozidriv Recess Head Screws Pozidriv recess head screws are the preferred standard on all Tait manufactured equip- ment. The very real advantages of this type of screw will not be realised unless the cor- rect screwdrivers are used by servicing personnel.
  • Page 16 31/01/96 Copyright TEL...

  • Page 17: Component Replacement

    Component Replacement Leaded Components Whenever components are removed from or fitted to the PCB, care must be taken to avoid damage to the track. The two satisfactory methods of removing components from PTH PCBs are detailed below. Note: The first method requires the use of a desoldering station, e.g. Philips SBC 314 or Pace MBT-100E.

  • Page 18: Surface Mount Devices

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

  • Page 19: To Replace Pa Transistors

    To Replace PA Transistors Caution: As the location of certain components in the PA is critical to perform- ance, it is important that any components removed or disturbed are exactly refitted in the same position. Caution: Before attempting to remove a transistor, measure the distance between the capacitors and transistor body to the nearest 0.5mm (meas- urements "A"...
  • Page 20 31/01/96 Copyright TEL...

  • Page 21: To Remove The T838 Pa Pcb From The Heatsink

    To Remove The T838 PA PCB From The Heatsink Most components are soldered topside only, but in some cases access to the underside of the PCB is necessary. Remove the cover from the N-connector shield. Remove the D-range connector. Remove the 10 PCB retaining screws (2 are hidden beneath the harmonic filter shield).
  • Page 22 31/01/96 Copyright TEL...

  • Page 23: To Remove Cased Mica Capacitors

    To Remove Cased Mica Capacitors Cased mica capacitors can be removed by heating the top with a heavy-duty soldering iron and gently lifting the capacitor off the PCB with a solder-resistant spike or equiva- lent. Copyright TEL 31/01/96...
  • Page 24 31/01/96 Copyright TEL...

  • Page 25: Software History

    Software History 23/11/89 BASEPROG Version 1 23/08/90 PGM800 Version 2 11/06/91 PGM800 Version 2.01 03/10/95 PGM800 Version 2.21 BASEPROG V1/PGM800 V2 T800 programming software was originally developed as BASEPROG V1 and released as PGM800 V2. PGM800 V2.01 The major changes introduced with V2.01 are as follows: •...

  • Page 26: Pgm800 V2.21

    PGM800 V2.21 PGM800 V2.21 is an updated and expanded version of the earlier PGM800 V2.01 soft- ware. PGM800 V2.21 includes many new and improved features over PGM800 V2.01. There are a number of changes to the user interface to make data entry and editing signifi- cantly easier.
  • Page 27 Engineering Division of Tait Electronics. These TIs may be used to update equipment or information, or to meet specific operational requirements. Printed below is a list of TIs applicable to T800 and T830 Series equipment. You may wish to file a copy of each TI in this Section for your own reference.
  • Page 28 31/01/96 Copyright TEL...
  • Page 29 Part B T835 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 30 31/01/96 Copyright TEL...
  • Page 31 T835 General Information This section provides a brief description of the T835 receiver, along with detailed speci- fications and a list of variants available. The following topics are covered in this section. Section Title Page Introduction Specifications 1.2.1 Introduction 1.2.2 General 1.2.3 RF Section...
  • Page 32 31/01/96 Copyright TEL...

  • Page 33: Introduction

    Introduction The T835 is a high performance FM base station receiver designed for single or mul- tichannel operation in the 136 to 174MHz frequency range. The receiver is a dual conversion superhet with a synthesised local oscillator. The first IF is 21.4MHz, allowing exceptionally high spurious signal rejection to be achieved in the receiver front end.

  • Page 34: Specifications

    EIA specification. However, there are several parameters for which performance according to the CEPT specification is given. Details of test methods and the conditions which apply for Type Approval testing in all countries can be obtained from Tait Electronics Ltd. 1.2.2 General Frequency Range ..

  • Page 35: Rf Section

    Signal Strength Indicator .. -115dBm to -70dBm, 3.5 to 6.5V at approx. 15dB/V Dimensions: Height .. 191mm Width .. 60mm Length .. 324mm Weight .. 2.13kg 1.2.3 RF Section IF Amplifiers: Frequencies .. 21.4MHz and 455kHz Bandwidths- Narrow Band (NB) ..

  • Page 36: Audio Section

    1.2.4 Audio Section Outputs Available .. line and monitor Frequency Response .. flat or de-emphasised (link selectable) Flat Response: Bandwidth .. 67 to 3400Hz Response .. within +1, -2dB of output level at 1kHz De-emphasised Response: CTCSS Band- Bandwidth .. 67 to 260Hz Response ..

  • Page 37: Versions

    • • • ±2.5ppm TCXO (-30°C to +60°C) Note: A TCXO with a stability of ±1ppm (0°C to +60°C) is available to suit specific requirements. Contact your nearest authorised Tait Dealer or Service Centre for further details. Copyright TEL 31/01/96...
  • Page 38 31/01/96 Copyright TEL...
  • Page 39 T835 Circuit Operation This section provides a basic description of the circuit operation of the T835 receiver. The following topics are covered in this section. Section Title Page Introduction Receiver Front End Mixer IF Circuitry Noise Mute (Squelch) Carrier Mute Audio Processor Power Supply And Regulator Synthesised Local Oscillator...
  • Page 40 31/01/96 Copyright TEL...

  • Page 41: Introduction

    Introduction Noise Mute Mixer Mixer Limiter Speaker Front 21.4MHz 455kHz Audio Processor 600Ω Line Detector Synthesised Second Local Local Oscillator Oscillator Carrier Mute 12.8MHz Master Oscillator RSSI Figure 2.1 T835 High Level Block Diagram The T835 receiver consists of a number of distinct stages: •...

  • Page 42: Receiver Front End

    Receiver Front End Local Oscillator (From Synthesiser) RF In 136-174MHz 2dB Pad Post 4-Pole Harmonic Doublet Doublet Mixer Crystal Filter Filter Filter Diplexer Filter Mixer 21.4MHz 2-Pole Crystal Mixer Ceramic Limiter Detector Pass (NE612) Filter (NE614) Filter (NE614) Filter Audio (To Audio Processor) 21.4MHz...

  • Page 43: Mixer

    Mixer (Refer to Figure 2.2.) IC301 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 +22dBm (typical) and this is fed to the mixer via a 2dB attenuator pad. A diplexer terminates the IF port of the mixer in a good 50 ohms, thus preventing unnecessary intermodulation distortion.

  • Page 44: Noise Mute (Squelch)

    Noise Mute (Squelch) (Refer to Figure 2.2.) The noise mute operates on the detected noise outside the audio bandwidth. An opera- tional amplifier in IC304 is used as an active band pass filter centred on 70kHz to filter out audio components. The noise spectrum is then further amplified in a variable gain, two-stage amplifier (Q306 &...

  • Page 45: Audio Processor

    Audio Processor Rx Gate Control Mute Switch Selectable Audio Volume Driver Filter Control Speaker Output Line Monitor Mute Switch Line Output Line Level Driver Transformer Adjustment Figure 2.3 T835 Audio Processor Block Diagram The recovered audio on pin 7 of IC303 is processed in a third order elliptic active filter to give the required response.

  • Page 46: Power Supply And Regulator

    Power Supply And Regulator 13.8V Nom. From Rear Switching D-Range Power Supply 13.8V Nom. Figure 2.4 T835 Power Supply And Regulator Block Diagram The T835 is designed to operate off a 10.8-16V DC supply (13.8V nominal). A 5.3V regu- lator (IC202) runs directly off the 13.8V rail, driving much of the synthesiser circuitry. This is used as the reference for a DC amplifier (IC201, Q200 &...

  • Page 47: Synthesised Local Oscillator

    Synthesised Local Oscillator VCO PCB Fixed Reference Phase Loop Output Divider Divider Detector Filter Buffer Buffer 12.8MHz +22dBm Reference L.O. Oscillator Programmable Prescaler Divider 40/41 Buffer Channel EPROM Memory Remote Channel Select Channel EPROM PCB Select Switches Figure 2.5 T835 Synthesiser Block Diagram The synthesiser employs a phase-locked loop (PLL) to lock a VCO to a given reference frequency.

  • Page 48: Received Signal Strength Indicator (Rssi)

    code amplifier stage (Q2, Q3) which supplies +10dBm (typically) to a further stage of amplification, Q5. This is the final amplifier on the VCO PCB, and delivers +22dBm (typically) to the receiver mixer input pad. A low level "sniff" is taken from the input to Q5 and used to drive the divider buffer for the VHF prescaler (IC1).
  • Page 49 T835 Initial Tuning & Adjustment The following section describes the full tuning and adjustment procedure and provides information on: • channel programming • channel selection • selecting required audio links • synthesiser alignment • receiver front end and IF alignment •...
  • Page 50 Figure Title Page Channel DIP Switch Setting Test Equipment Set-up 31/01/96 Copyright TEL...

  • Page 51: Channel Programming

    Channel Programming Up to 128 channel frequencies can be stored in the EPROM memory (IC1). Each channel can be addressed using the bank of 8 switches (SW1). The most significant bit of this switch is set according to the type of EPROM fitted: ON = 27C16 OFF = 27C64 Up to 8 channels may be addressed externally when the optional extra rear D-range...

  • Page 52: Audio Processor Links

    Audio Processor Links 3.3.1 General The links available for various circuit block options are listed by function as follows: Plug Link Function 1 - 2 Rx disable link PL100 2 - 3 not connected 1 - 2 flat response PL101 2 - 3 de-emphasised response 1 - 2...

  • Page 53: Audio Processor Linking Details For Ctcss

    3.3.2 Audio Processor Linking Details For CTCSS The audio processor links must be appropriately connected for the CTCSS option used, as shown in the table below. CTCSS Option PL105 PL106 standard, no CTCSS 2 - 3 2 - 3 CTCSS tone + speech to line output 1 - 2 2 - 3 internal CTCSS...

  • Page 54: Test Equipment Set-Up

    Test Equipment Set-up Set up the test equipment as shown below: Distortion Sinad Audio +13.8V Meter Meter Voltmeter Oscilloscope Line RF In RF Signal Receiver 600Ω Line Generator Probe External Speaker Modulation Output Audio Signal Generator 4Ω Speaker (Or 4Ω Resistor) Figure 3.2 Test Equipment Set-up Synthesiser Alignment •...

  • Page 55: Alignment Of Receiver Front End And If

    Alignment Of Receiver Front End And IF Note 1: In this and following sections deviation settings are given first for wide band sets, followed by settings in brackets for narrow band sets [ ]. Frequency Range Note 2: 136-156MHz: With the power supply switched off, solder bridge links 1-6 and link B in the front end.

  • Page 56: Noise Mute Adjustment

    Noise Mute Adjustment Connect pins 1 & 2 of PL104 to enable the noise mute. Align the receiver as instructed in Section 3.5 and Section 3.6. Set the RF level to -105dBm with 3kHz deviation [1.5kHz] at 1kHz. Set RV100 (gate sensitivity) fully anticlockwise. Adjust RV301 to close the mute (if necessary turn off the RF signal and then turn it on again).

  • Page 57: Rssi

    RSSI Align the receiver as instructed in Section 3.5 and Section 3.6. Apply an on-channel signal from the RF generator at a level of -100dBm with 3kHz deviation [1.5kHz] at 1kHz. Adjust RV303 to give 4.5V RSSI output on pin 5 on the rear D-range connector when measured with a high impedance DMM.

  • Page 58: Pgm800 Dip Switch Codes

    3.11 PGM800 DIP Switch Codes PGM800 channel numbers can range from 0-127 or 1-128, depending on which version you are using: Version Channel Numbers V2 and earlier 0-127 V2.01 1-128 V2.21 and later 0-127 or 1-128 The following sections provide DIP switch code lists for both numbering systems. 31/01/96 Copyright TEL...
  • Page 59 3.11.1 DIP Switch Codes For Channel Numbers 0-127 0 = off 1 = on Channel DIP Code Channel DIP Code Channel DIP Code X1111111 X1010010 X0100101 X1111110 X1010001 X0100100 X1111101 X1010000 X0100011 X1111100 X1001111 X0100010 X1111011 X1001110 X0100001 X1111010 X1001101 X0100000 X1111001 X1001100...

  • Page 60: Dip Switch Codes For Channel Numbers

    3.11.2 DIP Switch Codes For Channel Numbers 1-128 0 = off 1 = on Channel DIP Code Channel DIP Code Channel DIP Code X1111111 X1010010 X0100101 X1111110 X1010001 X0100100 X1111101 X1010000 X0100011 X1111100 X1001111 X0100010 X1111011 X1001110 X0100001 X1111010 X1001101 X0100000 X1111001 X1001100...
  • Page 61 T835 Functional Testing The following test procedures will confirm that the T835 has been tuned and adjusted correctly and is fully operational. Note: In this and following sections deviation settings are given first for wide band sets, followed by settings in brackets for narrow band sets [ ]. The following topics are covered in this section.
  • Page 62 31/01/96 Copyright TEL...

  • Page 63: Current Consumption

    Current Consumption Connect the T835 to a 13.8V power supply. Rotate the front panel mute pot. anticlockwise until the mute LED is extinguished. Turn the front panel "Monitor Mute" switch to the position. Check that the current in the 13.8V power cable is less than 350mA. Rotate the mute pot.

  • Page 64: Audio Distortion

    Audio Distortion The level of distortion measured at the line output gives a good indication of the accu- racy of the IF alignment. Apply an accurate on-channel signal from the RF generator at a level of -70dBm with 3kHz deviation [1.5kHz] at 1kHz. Adjust the front panel line level control (RV102) to give +10dBm into 600 ohms.

  • Page 65: Emphasised Audio Frequency Response

    De-emphasised Audio Frequency Response Set RV102 (line level) to provide 0dBm output at 1kHz modulating frequency. Sweep the modulating frequency, checking that the response closely follows that shown in Figure 4.1 - the limits should not be exceeded. The curve is shown for wide band sets. The narrow band response is simi- Note: lar, but rolls off earlier at 2.5kHz.

  • Page 66: Noise Mute (If Linked In)

    Noise Mute (If Linked In) Rotate the front panel mute pot. (RV100) fully anticlockwise. Apply an on-channel signal from the RF generator at a level of -110dBm with 3kHz deviation [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 67: Carrier Level Mute (Carrier Mute Linked In)

    Carrier Level Mute (Carrier Mute Linked In) Apply an on-channel signal from the RF generator at a level of -120dBm with 3kHz deviation [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 RV104 (i.e.
  • Page 68 31/01/96 Copyright TEL...
  • Page 69 If the fault still exists after having progressed through them in a logical manner, contact your nearest authorised Tait Dealer or Service Centre. Further assistance may be obtained from the Customer Support Group, Radio Infrastructure Division, Tait Elec- tronics Ltd, Christchurch, New Zealand.
  • Page 70 31/01/96 Copyright TEL...

  • Page 71: Visual Checks

    Visual Checks Remove the covers from the T835 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 is considered necessary, refer to Section 3 of Part A.

  • Page 72: Dc Checks

    DC Checks 5.3.1 Power Rails Refer to the test points & options diagrams for test point locations, and to the regulator fault finding chart (Section 5.5.1) for fault diagnosis. Check the 9V (TP2) and 13.8V (TP1) power supply test points in the audio com- partment with a DMM.

  • Page 73: Rf Checks

    RF Checks 5.4.1 VCO Frequency Check that the VCO is phase locked (refer to Section 5.3.2). Connect a frequency counter (level +19dBm) to the VCO input to the mixer (IC301). above Monitor the local oscillator frequency and check that it is 21.4MHz required receive frequency.

  • Page 74: Oscillator Stability

    5.4.3 Oscillator Stability 5.4.3.1 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 21.4MHz - a constant low fre- quency beat note should be heard. Tap the TCXO with a finger and replace it if the beat note permanently changes.
  • Page 75 Check that the swept response has a rounded top and no sharp non-linearities (refer to Figure 5.2). Figure 5.2 IF Swept Response Increase the RF level to -50dBm; the trace will now show the shape of the 455kHz ceramic filter (&XF303). Check that the response has no sharp non-linearities.

  • Page 76: Fault Finding Charts

    Fault Finding Charts Note: The standard test point designations as used in this section are as follows: 13.8V 5.5.1 Regulator Check for overheating components & short circuits. Check continuity 13.8V present on from D-range IC202 pin 3? connector pin 9. 5.3V present on Replace IC202.

  • Page 77: Synthesiser

    5.5.2 Synthesiser A (Refer to VCO circuit diagram) B (Refer to synth. circuit diagram) No VCO RF output. VCO out of lock. 9V present at +5V present at Check 5V reg. & Check 9V reg. VCO Q4/Q5? TCXO, IC3, IC5, supply resistor IC6, IC1 &...
  • Page 78 D (Refer to synth. & VCO C (Refer to synth. circuit diagram) circuit diagrams) VCO locked on Noisy synth; poor wrong freq? selectivity &/or poor residual FM. Correct channel selected? Set correct VCO phase locked? (switches on channel. 5-13V present on Go to B.

  • Page 79: Noise Mute

    5.5.3 Noise Mute Ensure PL104 is set for noise mute operation. Apply on channel signal *Modulated 3kHz [1.5kHz] @ -117dBm* to receiver. deviation @ 1kHz. Refer to Rx Audio on fault finding IC303 pin 7? chart. Rotate mute pot. RV100 Noise on Check components c/w &...

  • Page 80: Carrier Mute

    5.5.4 Carrier Mute Ensure PL104 is set for carrier mute operation. Apply on channel signal *Modulated by 1kHz signal with @ -95dBm* to receiver. 3kHz [1.5kHz] deviation. Audio on Refer to Rx fault IC303 pin 7? finding chart. Approx. 3.3V on Check for short circuits IC303 pin 5? and/or replace IC303.

  • Page 81: Receiver

    5.5.5 Receiver Poor sensitivity: worse than -117dBm. Ensure VCO RF & IF correctly aligned. High audio See Chart B distortion? (below). Check DC Replace conditions OK? faulty device. (see cct diagram) Check sensitivity into each stage (see 5.4.2) High audio Note: T.B.

  • Page 82: Audio

    5.5.6 Audio Apply on channel signal *Modulated 3kHz [1.5kHz] @ -117dBm* to receiver. deviation @ 1kHz. Refer to Rx Audio on fault finding IC303 pin 7? chart. Audio on Check components IC101 pin 1? around IC101. Audio at top of RV102 Replace C112.
  • Page 83 T835 PCB Information This section provides parts lists, a grid reference index, PCB layouts, test points and options draw- ings and circuit diagrams for the T835 receiver. This section contains the following information. Section Title Page Introduction 6.1.3 T835 Receiver PCB 220-01186-02 6.2.1 Copyright TEL...
  • Page 84 31/01/96 Copyright TEL...
  • Page 85 Introduction PCB Identification All PCBs are identified by a unique 10 digit number, the last 2 digits of which define the issue status. The issue status starts at 00 and increments through 01, 02, 03, etc. as the PCB is updated. Some issue PCBs never reach full production status and are therefore not included in this manual.
  • Page 86 Grid Reference Index To assist in locating components and labelled pads on the PCB layouts and circuit diagrams, a com- ponent grid reference index has been provided. This index lists the components and pads in alpha- betical order, along with the appropriate alphanumeric grid references, as shown below: PCB layout reference components listed...
  • Page 87 T835 Receiver PCB This section contains the following information. Section Page 220-01186-02 Parts List 6.2.3 Mechanical & Miscellaneous Parts 6.2.7 Grid Reference Index 6.2.9 PCB Layout - Top Side 6.2.13 PCB Layout - Bottom Side 6.2.14 Test Points & Options - Top Side 6.2.15 Test Points &...
  • Page 88 31/01/96 Copyright TEL...
  • Page 89 T835 Parts List (IPN 220-01186-02) 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). Those with a circuit reference are grouped by component type in numerical order.
  • Page 90 COIL A/W 3.5T/4.0MM HOR 0.8MM WIRE &C346 015-22820-01 CAP CER 0805 CHIP 82P 5% NPO 50V L304 050-00016-59 COIL TAIT 659 RF 3.5T C/W SLUG & CAN &C346 015-25100-08 CAP CER 0805 CHIP 10N 10% X7R 50V L305 050-00016-59 COIL TAIT 659 RF 3.5T C/W SLUG & CAN &C346...
  • Page 91 Description Description 036-17100-00 RES M/F 0805 CHIP 1M 5% R155 036-15150-00 RES M/F 0805 CHIP 15K 5% 036-12100-00 RES M/F 0805 CHIP 10E 5% R156 036-14560-00 RES M/F 0805 CHIP 5K6 5% 036-17100-00 RES M/F 0805 CHIP 1M 5% R157 036-16220-00 RES M/F 0805 CHIP 220K 5% 036-12220-00...
  • Page 92 SWITCH TOGGLE SPDT RT ANGLE PCB MT PAR T100 053-00010-17 XFMR T4030 LINE MATCH POTCORE T200 050-00016-50 COIL TAIT NO 650 455KHZ 5.6MM CAN VC301 028-02100-06 CAP TRIM 3/10P NPO TOP ADJ BLUE MUR TZ X301 274-00010-02 XTAL 20.945MHZ SPEC TE/15 C/W TEFLON IN &XF301...
  • Page 93 T835 Mechanical & Miscellaneous Parts (220-01186-02) Description Description 012-04150-01 CAP CER F/THRU 1N5 NO LEAD 349-00020-45 SCREW TAPTITE M4X20MM PAN POZI BZ (C1-C15) bottom cover 051-00006-02 SOLDER SPRING 1.3MM A4M1877 352-00010-08 NUT M3 COLD FORM HEX ST BZ 'D' plug x2, cover x2,vco x2. 062-00010-13 CAN 10MM SQ X 11MM SANWA 613 A4M1017 Fit over coil T200...
  • Page 94 31/01/96 Copyright TEL...
  • Page 95 T835 Grid Reference Index (IPN 220-01186-02) 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. The first digit in the circuit diagram reference is the sheet number, and the last two characters give the location of the component on that sheet.
  • Page 96 Device Circuit Device Circuit Device Circuit Device Circuit 3-R0 PL102 1:D3 2-L0 2:Q3 1-J2 &R152 2:E9 2-B7 IC202 1:S7 3-E1 2-L1 2:P3 1-J2 R153 2:C9 2-J3 IC301 1:K11 4-B4 2-L1 2:M5 1-L4 R154 2:D6 2-C1 IC302 1:H5 4-B0 PL103 1:D9 2-B9 2:M5 1-M3...
  • Page 97 Device Circuit Device Circuit Device Circuit Device Circuit R347 2:F9 4-J2 R348 2:G9 4-J2 R349 2:G8 4-K1 R350 2:G9 4-K2 R351 2:G9 4-L1 R352 2:G9 4-L1 R353 2:G10 4-M1 R354 2:G9 4-M1 R355 2:G10 4-M1 R356 2:G11 4-N1 R357 2:F10 4-N1 R358 2:G8...
  • Page 98 31/01/96 Copyright TEL...
  • Page 99 T835 PCB Information B6.2.13 M830-00 T835 PCB Layout Top Side 220-01186-02 Copyright TEL 31/01/96...
  • Page 100 B6.2.14 T835 PCB Information M830-00 T835 PCB Layout Bottom Side 220-01186-02 31/01/96 Copyright TEL...
  • Page 101 T835 PCB Information B6.2.15 M830-00 T835 Test Points & Options Top Side 220-01186-02 Copyright TEL 31/01/96...
  • Page 102 B6.2.16 T835 PCB Information M830-00 T835 Test Points & Options Bottom Side 220-01186-02 31/01/96 Copyright TEL...
  • Page 103 T835 PCB Information B6.2.17 M830-00 Sheet 1 T835 Synthesiser 220-01186-02 Copyright TEL 31/01/96...
  • Page 104 B6.2.18 T835 PCB Information M830-00 6K8S 3K9S Sheet 2 T835 Audio Processor - 220-01186-02 31/01/96 Copyright TEL...
  • Page 105 T835 PCB Information B6.2.19 M830-00 Sheet 3 T835 Regulator 220-01186-02 Copyright TEL 31/01/96...
  • Page 106 B6.2.20 T835 PCB Information M830-00 8K2S Sheet 4 T835 Receiver - 220-01186-02 31/01/96 Copyright TEL...
  • Page 107 Part C T836 Transmitter & T837 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 & Adjustment Functional Testing Fault Finding PCB Information...
  • Page 108 31/01/96 Copyright TEL...
  • Page 109 T836/837 General Information This section provides a brief description of the T836 transmitter and T837 exciter, along with detailed specifications and a list of variants available. The following topics are covered in this section. Section Title Page Introduction Specifications 1.2.1 Introduction 1.2.2 General...
  • Page 110 31/01/96 Copyright TEL...

  • Page 111: Introduction

    Introduction The T836 is a synthesised, FM base station transmitter for single or multichannel opera- tion in the 136 to 174MHz frequency range with a standard power output of 25W. The RF section of the transmitter comprises a frequency synthesiser which provides 170mW of frequency modulated RF drive to a two stage, wide band output driver followed by a 25W power amplifier.

  • Page 112: Specifications

    EIA specification. However, there are several parameters for which performance according to the CEPT specification is given. Details of test methods and the conditions which apply for Type Approval testing in all countries can be obtained from Tait Electronics Ltd. 1.2.2 General Frequency Range ..

  • Page 113: Rf Section

    Dimensions: Height .. 191mm Width .. 60mm Length - T836 .. 322mm - T837 .. 316mm Weight .. 2.1kg Time-Out Timer (optional) .. 1 to 4 minutes (adjustable) Tail Timer .. 5ms to 4 seconds (adjustable) Transmit Key Time .. <25ms Duty Cycle (T836 Only) ..

  • Page 114: Audio Processor

    1.2.4 Audio Processor Inputs Available .. line, microphone and CTCSS Line Input: Impedance .. 600 ohms (balanced) Sensitivity (60% modulation @ 1kHz)- With Compressor .. -50dBm Without Compressor .. -30dBm Microphone Input: Impedance .. 600 ohms Sensitivity (60% modulation @ 1kHz)- With Compressor ..

  • Page 115: Versions

    • • • ±2.5ppm TCXO (-30°C to +60°C) Note: A TCXO with a stability of ±1ppm (0°C to +60°C) is available to suit specific requirements. Contact your nearest authorised Tait Dealer or Service Centre for further details. Copyright TEL 31/01/96...
  • Page 116 31/01/96 Copyright TEL...
  • Page 117 T836/837 Circuit Operation This section provides a basic description of the circuit operation of the T836 transmitter and T837 exciter. The following topics are covered in this section. Section Title Page Introduction Synthesiser 2.3.1 Two-Point Modulation 2.3.2 VCO Supply Audio Processor 2.4.1 General 2.4.2...
  • Page 118 31/01/96 Copyright TEL...

  • Page 119: Introduction

    Introduction The individual circuit blocks which make up the T836 and T837 are: • synthesiser • VCO • audio processor • drive amplifier • power amplifier (T836 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 120: Synthesiser

    Synthesiser (Refer to Figure 2.3.) The synthesiser employs a phase-locked loop (PLL) to lock a voltage controlled oscilla- tor (VCO) to a given reference frequency. A reference oscillator at 12.8MHz (IC1) is buff- ered (IC7c & b) and divided down to 200kHz (IC4). This 200kHz square wave is then summed with the modulating audio and passed to an integrator (IC7f, Q8, Q9).
  • Page 121 Modulation VCO PCB Output Fixed Phase Reference Phase Loop Buffer Buffer Divider Modulator Divider Detector Filter +22dBm 12.8MHz Reference L.O. Oscillator Divider Programmable Prescaler Buffer Reference Divider Modulation 40/41 Channel EPROM Memory Remote Channel Select Channel Select Switches EPROM PCB Figure 2.3 T836/837 Synthesiser Block Diagram Copyright TEL 31/01/96...

  • Page 122: Vco

    The VCO transistor (Q1) operates in a common source configuration, with an LC tank circuit coupled between its gate and drain to provide the feedback necessary for oscilla- tion. The VCO control voltage from the loop filter (IC6) is applied to the varicaps (D1- D4) to facilitate tuning within an 8MHz band of frequencies.

  • Page 123: Audio Processor

    Audio Processor Compressor CTCSS IC102a Mic. IC102b Pre-amp. Q103, Q104 Pre- Low Pass Microphone emphasis Limiter Deviation Filter Buffer Q101 VCO Mod. Line IC102c IC102d RV106 IC103b IC103c IC104b Input IC103a Integrator Transformer Ref. Mod. Ref. Mod. Adjust Carrier RV105 IC103d Tx Enable Tx Key...

  • Page 124: Keying Inputs

    2.4.3 Keying Inputs There are four ways to key the exciter: • pulling the Tx-key line low (pin 13 on the D-range connector at the rear of the set); • pushing the "Carrier" button on the front panel - this will inhibit all audio; •...

  • Page 125: Power Supply & Regulator Circuits

    Power Supply & Regulator Circuits Buffer Tx Timer Tail Timer Tx Enable Q211 IC202a IC202b IC202c Tx Reg. 13.8V Switching Nominal Power Supply Amp. IC202d IC201 Q208 Q209 Q212 Q210 13.8V Nominal Figure 2.5 T836/837 Power Supply & Regulator Block Diagram The T836 and T837 are designed to operate from a 10.8-16V DC supply, although the standard test voltage is 13.8V.

  • Page 126: T836 Drive Amplifier & Pa

    T836 Drive Amplifier & PA (Refer to Figure 2.1.) A two-stage, wide band amplifier (Q300, Q301) provides an output level of approxi- mately 500mW (+27dBm) for an input of 170mW (+22dBm) from the VCO. An 11V zener (D351) on the supply of IC350 provides a 10.5V regulated rail for the exciter. To reduce the spurious output level the synthesiser out-of-lock signal inhibits the exciter via Q350 and IC350a.
  • Page 127 T836/837 Initial Tuning & Adjustment The following section describes the full tuning and adjustment procedure and provides information on: • channel programming • channel selection • selecting required audio links • synthesiser alignment • PA alignment (T836 only) • modulator adjustment •...
  • Page 128 Section Title Page PGM800 DIP Switch Codes 3.11 3.9.1 DIP Switch Codes For Channel Numbers 0-127 3.12 3.9.2 DIP Switch Codes For Channel Numbers 1-128 3.13 Figure Title Page Channel DIP Switch Setting T836/837 Test Equipment Set-up 31/01/96 Copyright TEL...

  • Page 129: Channel Programming

    Channel Programming Up to 128 channel frequencies can be stored in the EPROM memory (IC1). Each channel can be addressed using the bank of 8 switches (SW1). The most significant bit of this switch is set according to the type of EPROM fitted: ON = 27C16 OFF = 27C64 Up to 8 channels may be addressed externally when the optional extra rear D-range...

  • Page 130: Audio Processor Links

    Audio Processor Links 3.3.1 Link Details The links available for various circuit block options are listed by function as follows: Plug Link Function not connected PL100 microphone pre-amp. output to compressor input microphone pre-amp. output to multiplexer input multiplexer output to pre-emphasis input PL101 multiplexer output to compressor input multiplexer output to limiter input...

  • Page 131: Test Equipment Set-Up

    Test Equipment Set-up Frequency 20dB pad: exciter Counter 40dB pad: transmitter Line I/P RF O/P Modulation Exciter/ Ω Meter Audio Transmitter Generator CTCSS I/P AF O/P Audio RF Power Audio Oscilloscope Voltmeter Meter Voltmeter Figure 3.2 T836/837 Test Equipment Set-up Copyright TEL 31/01/96...

  • Page 132: Synthesiser Alignment

    Synthesiser Alignment • Ensure that the EPROM (IC1) has been programmed with the required frequen- cies using PGM800 software. • Single Channel Select a channel on the EPROM PCB DIP switch. Multichannel Select the middle channel via the EPROM PCB DIP switch. •...

  • Page 133: Pa Alignment (T836 Only)

    PA Alignment (T836 Only) Check that the exciter is connected to the PA with the coaxial link. Connect an RF power meter to the PA output. Turn &RV356 (power control) fully clockwise. Measure and record the voltage (VL) at &L439; perform this measurement at room temperature so that the NTC &R482 is close to 25°C.

  • Page 134: Audio Processor

    Audio Processor 3.8.1 Two Point Modulation The T836 and T837 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 135: Line Level Without Compressor

    Adjust RV100 (line sensitivity) fully clockwise and earth the key line. Adjust RV106 (deviation) to set the peak deviation to ±4.7kHz [±2.3kHz]. Sweep the audio frequency from 100Hz to 4kHz and ensure that the maximum deviation does not exceed 4.7kHz [2.3kHz]. Readjust RV106 if necessary. Note: For multichannel operation this test should be performed on the channel with the highest deviation.

  • Page 136: Compressor On Microphone Input Only

    3.8.5.2 Compressor On Microphone Input Only Open the key line and plug a microphone jack into the front panel socket. Adjust RV104 (compression level) fully clockwise. Acoustically couple the microphone to a tone box (1kHz) and close the PTT switch. Increase the audio level until the demodulated waveform shows significant signs of clipping (approximately 4.5kHz [2.3kHz] deviation).
  • Page 137 PGM800 DIP Switch Codes PGM800 channel numbers can range from 0-127 or 1-128, depending on which version you are using: Version Channel Numbers V2 and earlier 0-127 V2.01 1-128 V2.21 and later 0-127 or 1-128 The following sections provide DIP switch code lists for both numbering systems. Copyright TEL 31/01/96...
  • Page 138 3.9.1 DIP Switch Codes For Channel Numbers 0-127 0 = off 1 = on Channel DIP Code Channel DIP Code Channel DIP Code X1111111 X1010010 X0100101 X1111110 X1010001 X0100100 X1111101 X1010000 X0100011 X1111100 X1001111 X0100010 X1111011 X1001110 X0100001 X1111010 X1001101 X0100000 X1111001 X1001100...
  • Page 139 3.9.2 DIP Switch Codes For Channel Numbers 1-128 0 = off 1 = on Channel DIP Code Channel DIP Code Channel DIP Code X1111111 X1010010 X0100101 X1111110 X1010001 X0100100 X1111101 X1010000 X0100011 X1111100 X1001111 X0100010 X1111011 X1001110 X0100001 X1111010 X1001101 X0100000 X1111001 X1001100...
  • Page 140 31/01/96 Copyright TEL...
  • Page 141 T836/837 Functional Testing The following test procedures will confirm that the T836/837 has been tuned and adjusted correctly and is fully operational. Refer to Figure 3.2 for the test equipment set-up. In this and following sections deviation settings are given first for wide Note: band sets, followed by settings in brackets for narrow band sets [ ].
  • Page 142 31/01/96 Copyright TEL...
  • Page 143 Current Consumption Connect the T836/837 to a 13.8V power supply. Connect an RF power meter to the T836/837 output socket. Check that the current in the 13.8V power cable is less than 120mA. Key the T836/837 (the "Carrier On" LED should light). T836 Only: Adjust &RV356 (power control) to obtain 25W output power.
  • Page 144 Reset RV202 fully clockwise. Connect the key line to earth, then disconnect, ensuring that the T836/837 turns off immediately the key line is broken. Set RV202 for the required tail time. Transmit Timer Ensure that R257 is in circuit. Adjust RV201 fully anticlockwise. Earth the key line.
  • Page 145 Peak + max. dev. = +1.0kHz @ 1000Hz Peak - max. dev. = -1.0kHz @ 1000Hz Frequency (Hz) Figure 4.1 T836/837 Pre-emphasis Response Peak + max. dev. = +4.9kHz @ 1500Hz Peak - max. dev. = -4.4kHz @ 2500Hz Above limiting (steady-state) Frequency (Hz) Figure 4.2 T836/837 Limiting Response Copyright TEL...
  • Page 146 Audio Level Input Sensitivity • Adjust RV100 (line sensitivity) fully clockwise. • Check that the input sensitivities are better than those specified below: Line Input 600 ohms, 3kHz [1.5kHz] deviation at 1kHz: with compressor -50dBm without compressor -30dBm Microphone Input 600 ohms, 3kHz [1.5kHz] deviation at 1kHz: with compressor -75dBm...
  • Page 147 If the fault still exists after having progressed through them in a logical manner, contact your nearest authorised Tait Dealer or Service Centre. Further assistance may be obtained from the Customer Support Group, Radio Infrastructure Division, Tait Elec- tronics Ltd, Christchurch, New Zealand.
  • Page 148 31/01/96 Copyright TEL...

  • Page 149: Visual Checks

    Visual Checks Remove the covers from the T836/837 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 150: Dc Checks

    DC Checks 5.3.1 Power Rails Refer to the test points and options diagrams (Section 6) for test point locations, and to the regulator fault finding chart (Section 5.5.1) for fault diagnosis. Check the 13.8V (TP1 in the transmitter) and 9V (TP2 in the synthesiser) supplies at their test points with a DMM.

  • Page 151: Rf Checks

    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. 5.4.1 T836 Drive Power Refer to the drive amplifier fault finding chart (Section 5.5.3). Ensure that the VCO locks (refer to Section 5.3.2).

  • Page 152: Audio And Modulation

    5.4.4 Audio And Modulation Refer to the audio processor fault finding chart (Section 5.5.6). Set up the audio processor as described in Section 3.8. Check that the demodulated RF output has the frequency response referred to in Section 4.6 with at least 5kHz [2.5kHz] deviation available at 1kHz modulating frequency.

  • Page 153: Fault Finding Charts

    Fault Finding Charts 5.5.1 Regulator Check for overheating components & short circuits. Check continuity 13.8V present on from D-range IC201 pin 3? connector pin 9. 5.3V present on Replace IC201. IC201 pin 1? 9.0V present Check Q210, on TP2? Q209 & IC202d. Check Q208 is 20V present switching at...

  • Page 154: Synthesiser

    5.5.2 Synthesiser A (Refer to VCO circuit diagram) B (Refer to synth. circuit diagram) No VCO RF output. VCO out of lock. 9V reg. present at Check Tx reg., +5V present at Check 5V reg. & VCO amp. Q4/Q5? Q211 & 9V reg. TCXO, IC7, IC4, supply resistor IC3, IC5 &...
  • Page 155 D (Refer to synth. & VCO C (Refer to synth. circuit diagram) circuit diagrams) VCO locked on Noisy synth; wrong freq? poor residual FM. Correct channel VCO phase locked? selected? Set correct 5-15V present on Go to B. (switches on channel.

  • Page 156: T836 Drive Amplifier

    5.5.3 T836 Drive Amplifier Key exciter & lock synthesiser. 3.5V on Q300 collector? 10.5V on Q301 10.5V on Q352 11V on IC350a collector? collector? pin 1? 0.4V on Q304 base? Check continuity of power rails Check D351 & DC paths to &...
  • Page 157 5.5.4 T836 PA & Power Control Normal operating conditions: Set &RV356 power control Forward power = 3.2V approx. fully clockwise; Reverse power = 0.3V approx. Check &Q423, synth. locked; &Q424 & circuitry, IC350a pin 2 = 2V key Tx. LP filter. IC350a pin 3 = 3.8V IC350a pin 1...

  • Page 158: T837 Exciter Drive Amplifier

    5.5.5 T837 Exciter Drive Amplifier Key exciter & lock synthesiser. 3.5V Q300 collector? 10.5V at Q352 Check 10.5V Q301 collector? collector? power rails. 0.4V Q300 base? 11V present on Check D351 IC350a pin 1? & IC350. Check Q351 & Q352. >2.2V RF at Check VCO.

  • Page 159: Audio Processor

    5.5.6 Audio Processor Key exciter & lock synthesiser. Connect 1kHz audio to CTCSS input. Check audio Does exciter Audio output at path to VCO modulate? IC104 pin 7? control line. Check alignment Audio output at Check of modulators. IC103c pin 8? buffer IC104b.
  • Page 160 31/01/96 Copyright TEL...
  • Page 161 T836/837 PCB Information This section provides parts lists, a grid reference index, PCB layouts, test points and options draw- ings and circuit diagrams for the T836 transmitter and T837 exciter. The T836 and T837 are built on a common main PCB, with the T836 having the additional compo- nents fitted to the PA section of the board.
  • Page 162 31/01/96 Copyright TEL...
  • Page 163 Introduction PCB Identification All PCBs are identified by a unique 10 digit number, the last 2 digits of which define the issue status. The issue status starts at 00 and increments through 01, 02, 03, etc. as the PCB is updated. Some issue PCBs never reach full production status and are therefore not included in this manual.
  • Page 164 Grid Reference Index To assist in locating components and labelled pads on the PCB layouts and circuit diagrams, a com- ponent grid reference index has been provided. This index lists the components and pads in alpha- betical order, along with the appropriate alphanumeric grid references, as shown below: PCB layout reference components listed...
  • Page 165 T836 Transmitter & T837 Exciter PCB This section contains the following information. Section Page 220-01178-02 T836 Parts List 6.2.3 T836 Mechanical & Miscellaneous Parts 6.2.7 T837 Parts List 6.2.9 T837 Mechanical & Miscellaneous Parts 6.2.12 Grid Reference Index 6.2.13 PCB Layout - Top Side 6.2.17 PCB Layout - Bottom Side 6.2.18...
  • Page 166 31/01/96 Copyright TEL...
  • Page 167 T836 Parts List (IPN 220-01178-02) 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). Those with a circuit reference are grouped by component type in numerical order.
  • Page 168 Description Description C233 015-06100-08 CAP CER 1206 CHIP 100N 10% X7R 50V 052-08160-25 COIL A/W 2.5T/6.0MM HOR 0.8MM WIRE C300 015-24470-08 CAP CER 0805 CHIP 4N7 10% X7R 50V L300 052-08125-15 COIL A/W 1.5T/2.5MM HOR 0.8MM WIRE C303 015-24100-08 CAP CER 0805 CHIP 1N 10% X7R 50V L303 065-00010-04 BEAD FERRITE F8 4X2X5MM...
  • Page 169 Description Description 036-14470-00 RES M/F 0805 CHIP 4K7 5% R188 036-17100-00 RES M/F 0805 CHIP 1M 5% 036-15100-00 RES M/F 0805 CHIP 10K 5% R189 036-13560-00 RES M/F 0805 CHIP 560E 5% 036-15100-00 RES M/F 0805 CHIP 10K 5% R190 036-14220-00 RES M/F 0805 CHIP 2K2 5% 036-15100-00...
  • Page 170 SKT COAX MINI JACK PCB MTG ANGLED SK401 240-02100-44 SKT COAX MINI JACK PCB MTG ANGLED SW101 232-00010-26 SWITCH PUSH SPDT RT ANGLE PCB MTG NO B T100 053-00010-17 XFMR T4030 LINE MATCH POTCORE T200 050-00016-50 COIL TAIT NO 650 455KHZ 5.6MM CAN 31/01/96 Copyright TEL...
  • Page 171 T836 Mechanical & Miscellaneous Parts (220-01178-02) Description Description 012-04150-01 CAP CER F/THRU 1N5 NO LEAD (C1-C15) 345-00040-11 SCREW M3X10MM PAN POZI ST BZ For Final Carcassing Kit 051-00006-02 SOLDER SPRING 1.3MM A4M1877 345-00040-20 SCREW M3*8MM BUTTON SKT HD BLACK ZINC PHOS 065-00010-08 BEAD FERRITE 4S3 3*0.7*10MM RED front panel...
  • Page 172 31/01/96 Copyright TEL...
  • Page 173 T837 Parts List (IPN 220-01178-02) 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). Those with a circuit reference are grouped by component type in numerical order.
  • Page 174 Description Description C300 015-24470-08 CAP CER 0805 CHIP 4N7 10% X7R 50V Q209 000-00011-30 (S) XSTR BC557B PNP AF SML SIG TO92 C303 015-24100-08 CAP CER 0805 CHIP 1N 10% X7R 50V Q210 000-00012-15 (S) XSTR BD234 PNP AF PWR TO126 C308 015-24100-08 CAP CER 0805 CHIP 1N 10% X7R 50V...
  • Page 175 053-00010-17 XFMR T4030 LINE MATCH POTCORE R182 036-14220-00 RES M/F 0805 CHIP 2K2 5% T200 050-00016-50 COIL TAIT NO 650 455KHZ 5.6MM CAN R183 036-14560-00 RES M/F 0805 CHIP 5K6 5% *R184 036-15150-00 RES M/F 0805 CHIP 15K 5% *R184...
  • Page 176 T837 Mechanical & Miscellaneous Parts (220-01178-02) Description Description 012-04150-01 CAP CER F/THRU 1N5 NO LEAD (C1-C15) 345-00040-11 SCREW M3X10MM PAN POZI ST BZ For Final Carcassing Kit 051-00006-02 SOLDER SPRING 1.3MM A4M1877 345-00040-20 SCREW M3*8MM BUTTON SKT HD BLACK ZINC PHOS 065-00010-08 BEAD FERRITE 4S3 3*0.7*10MM RED front panel...
  • Page 177 T836/837 Grid Reference Index (IPN 220-01186-02) 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. The first digit in the circuit diagram reference is the sheet number, and the last two characters give the location of the component on that sheet.
  • Page 178 Device Circuit Device Circuit Device Circuit Device Circuit IC350 1:H10 4-D8 3-B9 2:R4 1-H8 R182 2:B5 2-L5 4-D5 3-B9 2:R4 1-H7 R183 2:D6 2-L2 4-F8 3-B8 2:S4 1-H7 *R184 2:E4 2-Q5 LOW-PWR 1:G11 4-E6 3-B8 2:S4 1-H6 *R185 2:E4 2-Q5 1:K5 1-B4 3-B6...
  • Page 179 Device Circuit Device Circuit Device Circuit Device Circuit &R367 2:H10 4-E7 R417 2:G10 4-D8 R420 2:G10 4-C7 R421 2:H10 4-D7 R422 1:H8 4-L6 R423 1:J8 4-L6 R424 1:H8 4-N5 &R425 1:G9 4-Q5 &R426 1:G9 4-Q5 &R427 1:F9 4-Q4 &R428 1:G8 4-Q4 &R429 2:G11...
  • Page 180 31/01/96 Copyright TEL...
  • Page 181 T836/837 PCB Information C6.2.17 M830-00 T836/837 PCB Layout Top Side 220-01178-02 Copyright TEL 31/01/96...
  • Page 182 C6.2.18 T836/837 PCB Information M830-00 T836/837 PCB Layout Bottom Side 220-01178-02 31/01/96 Copyright TEL...
  • Page 183 T836/837 PCB Information C6.2.19 M830-00 T836/837 Test Points & Options Top Side 220-01178-02 Copyright TEL 31/01/96...
  • Page 184 C6.2.20 T836/837 PCB Information M830-00 T836/837 Test Points & Options Bottom Side 220-01178-02 31/01/96 Copyright TEL...
  • Page 185 T836/837 PCB Information C6.2.21 M830-00 Sheet 1 T836/837 Synthesiser 220-01178-02 Copyright TEL 31/01/96...
  • Page 186 C6.2.22 T836/837 PCB Information M830-00 Sheet 2 T836/837 Audio Processor - 220-01178-02 31/01/96 Copyright TEL...
  • Page 187 T836/837 PCB Information C6.2.23 M830-00 Sheet 3 T836/837 Regulator 220-01178-02 Copyright TEL 31/01/96...
  • Page 188 C6.2.24 T836/837 PCB Information M830-00 Sheet 4 T836/837 Exciter/PA - 220-01178-02 31/01/96 Copyright TEL...
  • Page 189 Part D T838 Power Amplifier 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 Tuning & Adjustment Fault Finding PCB Information Copyright TEL...
  • Page 190 31/01/96 Copyright TEL...
  • Page 191 T838 General Information This section provides a brief description of the T838 power amplifier, along with detailed specifications and a list of variants available. The following topics are covered in this section. Section Title Page Introduction Specifications 1.2.1 Introduction 1.2.2 General Versions Copyright TEL...
  • Page 192 31/01/96 Copyright TEL...
  • Page 193 The circuitry is built on a single PCB which is mounted directly on a die-cast chassis/ heatsink. The T838 has a width of 60mm, occupying a single module in a Tait rack shelf (T99-770) which will accommodate up to seven standard modules to give an attractive and con- venient installation.
  • Page 194 EIA specification. However, there are several parameters for which performance according to the CEPT specification is given. Details of test methods and the conditions which apply for Type Approval testing in all countries can be obtained from Tait Electronics Ltd. 1.2.2 General...
  • Page 195 Spurious Emissions: Conducted - Transmit .. -36dBm to 1GHz -30dBm to 4GHz - Standby .. -57dBm to 1GHz -47dBm to 4GHz Radiated - Transmit .. -36dBm to 1GHz -30dBm to 4GHz - Standby .. -57dBm to 1GHz -47dBm to 4GHz Operating Temperature Range ..
  • Page 196 Versions Version Description • 136-174MHz 31/01/96 Copyright TEL...
  • Page 197 T838 Circuit Operation This section provides a basic description of the circuit operation of the T838 power amplifier. The following topics are covered in this section. Section Title Page Introduction RF Circuitry Control Circuitry 2.3.1 Power Control 2.3.2 Thermal Protection 2.3.3 Forward And Reverse Power Alarms 2.3.4...
  • Page 198 31/01/96 Copyright TEL...

  • Page 199: Introduction

    Introduction Power Output Power Control -t° Final Power Power Directional Splitter Combiner Coupler RF In RF Out Pre- Drive Low Pass driver Filter Final Figure 2.1 T838 High Level Block Diagram The T838 comprises a four-stage RF power amplifier, the final two stages of which are combined, and extensive control circuitry.

  • Page 200: Rf Circuitry

    RF Circuitry Phasing Section Final Forward Power Power Control CV76 Power Power Directional Combiner Coupler Splitter Type N SMC In Output (800mW) (60W) Low Pass Filter Final CV57 Reverse Power Phasing Section CV96 Figure 2.2 T838 RF Circuitry Block Diagram The RF from the exciter (approximately 800mW) is fed to the power controlled stage Q8.

  • Page 201: Control Circuitry

    Control Circuitry Reverse Power Meter IC1D Switch Reverse Power Alarm Comparator Forward Power Meter Enable Directional Coupler RF Out RV16 RV10 Switch IC1A Forward Power Alarm Comparator +13.8V Integrator Power To Q8 Pre-driver RV32 IC1B Temperature Shutdown Shutdown Power Level RV35 IC1C RV39...

  • Page 202: Thermal Protection

    2.3.2 Thermal Protection At excessively high temperatures the output power will automatically reduce to a preset level, thus preventing the PA from overheating. An NTC (R37), being part of a voltage divider (R36, R37), senses the internal tempera- ture of the PA close to the output balance resistor (R69) and applies a voltage to a com- parator (IC1c, pin 9).
  • Page 203 T838 Initial Tuning & Adjustment The following section describes the full tuning and adjustment procedure to be carried out before operating the T838. The following topics are covered in this section. Section Title Page Test Equipment Required Optimising Intermodulation Performance Preliminary Checks RF Alignment Setting The Output Power...
  • Page 204 31/01/96 Copyright TEL...

  • Page 205: Test Equipment Required

    Test Equipment Required • DC power supply capable of delivering 15A at 13.8V (e.g. Tait T807). • Multimeter or DMM (e.g. Fluke 77). • RF power meter usable 136-174MHz (e.g. Bird 43 with 5 & 100W elements). • Thru-line wattmeter with 5W element.

  • Page 206: Optimising Intermodulation Performance

    Optimising Intermodulation Performance TL1 and TL2 are phasing lines supplied cut to the maximum length at the bottom of the band. If it is necessary to minimise IM products, TL1 and TL2 may be cut to suit the mid- switching range frequency, using the formula: 5250 length of centre conductor (cm) frequency (MHz)

  • Page 207: Rf Alignment

    RF Alignment Refer to the circuit diagram in Section 5. Note 1: The power amplifier circuit is 'broad band'. If the T838 is being retuned to a frequency less than 8MHz from the frequency already set up, there will be no need to retune the PA circuit.

  • Page 208: Setting The Output Power

    Setting The Output Power Note 1: The PA cover shield should be in position when the metering and power controls are set up. The actual power used may be limited by regulatory requirements (e.g. NZ Note 2: 33W, Australia 50W). Once the PA has been tuned to full power, set the output power by adjusting RV32 (the front panel power adjust control) to any desired output power between 10 and 60W.

  • Page 209: Setting Alarm Levels

    Setting Alarm Levels Note 1: The PA cover shield should be in position when setting the forward and reverse power alarm levels. If forward and reverse power metering is being used, set up their calibration Note 2: (Section 3.6 and Section 3.7) before setting the alarm levels. 3.8.1 Forward Power Power up the T838 and adjust the power output pot.

  • Page 210: Temperature Shutdown

    Temperature Shutdown Note: The temperature shutdown circuit is factory set to approximately 130°C and RV35 and RV39 should not be readjusted if normal operation is required. Power up the T838 and adjust the power control pot. (RV32) for the normal oper- ating power level.
  • Page 211 If the fault still exists after having progressed through them in a logical manner, contact your nearest authorised Tait Dealer or Service Centre. Further assistance may be obtained from the Customer Support Group, Radio Infrastructure Division, Tait Elec- tronics Ltd, Christchurch, New Zealand.
  • Page 212 31/01/96 Copyright TEL...

  • Page 213: Visual Checks

    Visual Checks Remove the cover from the T838 and inspect the PCB for damaged or broken com- ponents, paying particular attention to the surface mounted devices (SMD's). Check for defective solder joints. If repair or replacement is considered necessary, refer to Sections 3, 4 and 5 of Part A. Component Checks If a transistor is suspected of faulty operation, an indication of its performance can be assessed by measuring the forward and reverse resistance of the junctions.

  • Page 214: Rf Checks

    RF Checks 4.4.1 General 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 PA Fault Finding Chart (Section 4.6.1). For problems with the power control circuitry, refer to the Power Control Fault Finding Chart (Section 4.6.2).

  • Page 215: Voltage Chart

    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 8.7V 7.0V 6.6V 0.0V 0.5V 5.5V 13.8V 13.0V 13.8V...

  • Page 216: Fault Finding Charts

    Fault Finding Charts 4.6.1 Set RV32 power Using Coline M12 RF probe. output control to max. Provide 0.5W RF drive. >2.2V RF present Check input circuitry. at base of Q8? Check for shorts on base of Q8. Check 13.8V supply to Q8. >2.2V RF present Check for shorts on base of Q9.

  • Page 217: Power Control

    4.6.2 Power Control Normal operating conditions: FP at R17 = 2.8V (RV16 fully ccw) RP at R9 = 0.3V (RV8 fully ccw) IC1 pin 1 = 0.4V R33/RV32 = 7V = 13V Set RV32 power control to max. Provide 0.5W RF drive.
  • Page 218 31/01/96 Copyright TEL...
  • Page 219 T838 PCB Information This section provides parts lists, PCB layouts and circuit diagrams for the T838 power amplifier. This section contains the following information. Section Title Page Introduction 5.1.3 T838 PA PCB 220-01100-01 5.2.1 220-01100-02 5.2.11 220-01100-03 5.2.19 Copyright TEL 31/01/96...
  • Page 220 31/01/96 Copyright TEL...
  • Page 221 Introduction PCB Identification All PCBs are identified by a unique 10 digit number, the last 2 digits of which define the issue status. The issue status starts at 00 and increments through 01, 02, 03, etc. as the PCB is updated. Some issue PCBs never reach full production status and are therefore not included in this manual.
  • Page 222 31/01/96 Copyright TEL...
  • Page 223 T838 PA PCB This section contains the following information. Section Page 220-01100-01 Parts List 5.2.3 Mechanical & Miscellaneous Parts 5.2.5 PCB Layout - Bottom Side 5.2.7 PCB Layout - Top Side 5.2.8 Circuit Diagram 5.2.9 Wiring Diagram 5.2.10 220-01100-02 Parts List 5.2.11 Mechanical &...
  • Page 224 31/01/96 Copyright TEL...
  • Page 225 T838 Parts List (IPN 220-01100-01) 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). Those with a circuit reference are grouped by component type in numerical order.
  • Page 226 RES M/F PWR 47E 5% 1W 12X4.5MM 032-33330-00 RES M/F PWR 330E 5% 1W 12X4.5MM 032-31470-00 RES M/F PWR 4E7 5% 1W 12X4.5MM 032-33330-00 RES M/F PWR 330E 5% 1W 12X4.5MM 051-00005-17 COIL TAIT NO 517 DIRNL COUPLER 31/01/96 Copyright TEL...
  • Page 227 T838 Mechanical & Miscellaneous Parts (220-01100-01) Description Description 012-04150-01 CAP CER F/THRU 1N5 NO LEAD 345-00040-16 SCREW M3X20MM PAN POZI ST BZ 051-00006-02 SOLDER SPRING 1.3MM A4M1877 345-00040-20 SCREW M3*8MM BUTTON SKT HD BLACK ZINC PH 065-00010-08 BEAD FERRITE 4S3 3*0.7*10MM RED 349-00020-32 SCREW TAPTITE M3X8MM PAN POZI BZ 065-00010-11...
  • Page 228 31/01/96 Copyright TEL...
  • Page 229 T838 Parts List (IPN 220-01100-02) 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). Those with a circuit reference are grouped by component type in numerical order.
  • Page 230 RES M/F PWR 330E 5% 1W 12X4.5MM 056-00021-01 IND FXD 1.5UH AXIAL 056-00021-01 IND FXD 1.5UH AXIAL 051-00005-17 COIL TAIT NO 517 DIRNL COUPLER 056-00021-01 IND FXD 1.5UH AXIAL 052-08130-25 COIL A/W 2.5T/3.0MM HOR 0.8MM WIRE 052-08335-10 COIL A/W 1T/3.5MM SMD 0.8MM WIRE...
  • Page 231 T838 Mechanical & Miscellaneous Parts (220-01100-02) Description Description 012-04150-01 CAP CER F/THRU 1N5 NO LEAD 345-00040-16 SCREW M3X20MM PAN POZI ST BZ 051-00006-02 SOLDER SPRING 1.3MM A4M1877 345-00040-20 SCREW M3*8MM BUTTON SKT HD BLACK ZINC PH 065-00010-08 BEAD FERRITE 4S3 3*0.7*10MM RED 349-00020-32 SCREW TAPTITE M3X8MM PAN POZI BZ 065-00010-11...
  • Page 232 31/01/96 Copyright TEL...
  • Page 233 T838 Parts List (IPN 220-01100-03) 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). Those with a circuit reference are grouped by component type in numerical order.
  • Page 234 Description Description 056-00021-01 IND FXD 1.5UH AXIAL 051-00005-17 COIL TAIT NO 517 DIRNL COUPLER 056-00021-01 IND FXD 1.5UH AXIAL 056-00021-01 IND FXD 1.5UH AXIAL 052-08130-25 COIL A/W 2.5T/3.0MM HOR 0.8MM WIRE 052-08335-10 COIL A/W 1T/3.5MM SMD 0.8MM WIRE 065-00010-04 BEAD FERRITE F8 4X2X5MM 052-08340-50 COIL A/W 5T/4.0MM SMD 0.8MM WIRE...
  • Page 235 T838 Mechanical & Miscellaneous Parts (220-01100-03) Description Description 012-04150-01 CAP CER F/THRU 1N5 NO LEAD 318-01011-00 RAIL A2M1872 BOTTOM T377 PA (FT1-FT15) 318-01012-00 RAIL A3M1873 TOP T377 PA 051-00006-02 SOLDER SPRING 1.3MM A4M1877 319-01152-00 SHIELD A3M2250 F/THRU MTG T857 051-00006-03 LEAD F/THRU 0.7MM TCW A4M2230 319-01175-00 (L) SHIELD T377/T838...
  • Page 236 31/01/96 Copyright TEL...
  • Page 237 Part E T800 Memory & T830 VCO PCB Information This part of the manual is divided into the sections listed below. These sections provide parts lists, PCB layouts and circuit diagrams for the T800 memory and T830 VCO PCBs. There is a detailed table of contents at the start of each section.
  • Page 238 31/01/96 Copyright TEL...
  • Page 239 Introduction PCB Identification All PCBs are identified by a unique 10 digit number, the last 2 digits of which define the issue status. The issue status starts at 00 and increments through 01, 02, 03, etc. as the PCB is updated. Some issue PCBs never reach full production status and are therefore not included in this manual.
  • Page 240 31/01/96 Copyright TEL...
  • Page 241 T800 Memory PCB This section contains the following information. Section Page 220-01144-00 Parts List Mechanical & Miscellaneous Parts PCB Layout - Top Side PCB Layout - Bottom Side Circuit Diagram Copyright TEL 31/01/96...
  • Page 242 T800 Memory PCB Parts List (IPN 220-01144-00) 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). Those with a circuit reference are grouped by component type in numerical order.
  • Page 243 T800 Memory PCB (IPN 220-01144-00) - Top Side Copyright TEL 31/01/96...
  • Page 244 T800 Memory PCB (IPN 220-01144-00) - Bottom Side 31/01/96 Copyright TEL...
  • Page 245 T800 Memory PCB Information E2.5 M830-00 T800 MEMORY T800 Memory 220-01144-00 Copyright TEL 31/01/96...
  • Page 246 E2.6 T800 Memory PCB Information M830-00 31/01/96 Copyright TEL...
  • Page 247 T830 VCO PCB This section contains the following information. Section Page 220-01176-01 Parts List PCB Layout - Bottom Side PCB Layout - Top Side Circuit Diagram Copyright TEL 31/01/96...
  • Page 248 T830 VCO PCB Parts List (IPN 220-01176-01) 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). Those with a circuit reference are grouped by component type in numerical order.
  • Page 249 Description Description 220-01176-01 PCB T830 VCO 240-00025-36 PLUG 32WAY 1ROW PC MTG HARWIN PL-1 PL-2 345-00040-10 SCREW M3*6MM PAN POZI ST BZ 345-00060-08 SCREW M5 X 16 CHEESE SLOT PLASTIC T800 TO 350-00016-42 SPACER 5MM HI 8MM X M3 STUD 2.5MM X M3 HO 352-00010-14 NUT M5 HEX PLASTIC T800 TOROID 353-00010-10...
  • Page 250 31/01/96 Copyright TEL...
  • Page 251 T830 VCO PCB (IPN 220-01176-01) - Bottom Side Copyright TEL 31/01/96...
  • Page 252 T830 VCO PCB (IPN 220-01176-01) - Top Side 31/01/96 Copyright TEL...
  • Page 253 T830 VCO PCB Information E3.7 M830-00 T830 VCO 220-01176-01 Copyright TEL 31/01/96...
  • Page 254 E3.8 T830 VCO PCB Information M830-00 31/01/96 Copyright TEL...
  • Page 255 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 T835 receiver, T836 transmitter, T837 exciter and T838 power amplifier. Section Title Page...
  • Page 256 31/01/96 Copyright TEL...

  • Page 257: T835/836/837 Installation

    The T835 receiver, T836 transmitter and T837 exciter are designed for use in a standard 483mm rack frame using a Tait T800 Series guide which locates and mates the rear D-range connectors (refer to Figure 1.1, Figure 1.2 and Figure 1.3).

  • Page 258: Rack Wiring

    Rack Wiring Wire the D-range connector as shown in Figure 1.4 or Figure 1.5. Ensure that the cables are not subjected to any stresses due to tight bends or incorrect lengths. The RF coaxial cable to the N-type connector should be free from acute bends or twists. If access to the rear of the rack frame is restricted, the cable should be long enough to permit full withdrawal of the chassis from the guide.

  • Page 259: Power Supply

    Power Supply If a power supply other than an appropriate Tait model is used, ensure that it is capable of providing enough current to drive the T800 system and is also free from excessive ripple or noise. The system should be protected by the use of appropriately rated fuses in the power supply.
  • Page 260 31/01/96 Copyright TEL...

  • Page 261: T838 Installation

    T838 Installation Rack Mounting The T838 50W PA is designed for use in a standard 483mm rack frame using the sup- porting guide rails supplied with the units (refer to Figure 2.1). The lower guide rail is located in the rack frame with three screws, two at the rear and one at the front.

  • Page 262: Rack Wiring

    Figure 2.3 Latched Position Rack Wiring Wire the D-range connector as shown in Figure 2.4. Ensure that the cables are not sub- jected to any stresses due to tight bends or incorrect lengths. The RF coaxial cable to the N-type connector should be free from acute bends or twists. If access to the rear of the rack frame is restricted, the cable should be long enough to permit full withdrawal of the chassis from the guide.
  • Page 263 Power Supply If a power supply other than an appropriate Tait model is used, ensure that it is capable of providing enough current to drive the T800 system and is also free from excessive ripple or noise. Copyright TEL 31/01/96...
  • Page 264 31/01/96 Copyright TEL...
  • Page 265 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 T830 equipment for use in them. Section Title Page T835 Link Selectable Features Flat Or De-emphasised Response Mute Relay Control Mute Selection...
  • Page 266 Figure Title Page Talk Through Repeater Basic Configuration Remote Line Controlled Base Station 4-Wire to 2-Wire Convertor Receiver Disable Time vs Tail Time DC Loop Keying With Common Earth Isolated Constant Current Loop Current Detector Isolated Loop Current Switch Typical System 31/01/96 Copyright TEL...

  • Page 267: T835 Link Selectable Features

    T835 Link Selectable Features Flat Or De-emphasised Response The links of PL101 and PL103 may be set to give either a flat or de-emphasised audio frequency response (refer to Section 3.3 in Part B for further details). Mute Relay Control A relay with undedicated contacts (RL100) is available in the audio processor circuit block for various switching applications.
  • Page 268 300Hz High Pass Filter Link PL105 also allows the insertion of this filter to improve hum and noise perform- ance. 31/01/96 Copyright TEL...

  • Page 269: T836/837 Optional Features

    T836/837 Optional Features Audio Processor The T836 and T837 come with a number of link selectable features which give added system flexibility. Refer to Section 3.3 in Part C for further details. Line Transformer Inputs And Outputs The line transformer (T100) is designed to provide a balanced interface to 600 ohm lines. For normal operation the two centre connections (LINE I/P 2, LINE I/P 3) are shorted together, and the 600 ohm line is connected between LINE I/P 1 and LINE I/P 4.
  • Page 270 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 (e.g. CTCSS) is fitted to the exciter, keying may then be accomplished via the TX-EN-OPT pad in the audio processor.

  • Page 271: Local Microphone

    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 272 31/01/96 Copyright TEL...

  • Page 273: Line Controlled Base Without Talk Through

    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. When the relay is in its rest position, signals from the aerial are passed to the receiver and the demodulated output is fed via 600 ohm lines to the RCU.

  • Page 274: Transmitter Tail Timer

    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 a tail timer fitted: • the receiver disable timer must be set so that Rx/Dis > Tx/Tail; Tx Enable &...
  • Page 275 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 276 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 31/01/96 Copyright TEL...
  • Page 277 Part H T800 Ancillary Equipment This part of the manual gives a brief description of the ancillary equipment and acces- sory kits available for use with T800 series base station equipment. Section Page T708-91/92 Mains Power Supplies T800-01 Programming Kit T800-02 CTCSS Dencoder T800-03 Auxiliary D-Range T800-05 Guide Rail...
  • Page 278 31/01/96 Copyright TEL...
  • Page 279 T800 Ancillary Equipment T708-91/92 Mains Power Supplies The T708-91/92 mains power supplies are designed to power the T800-60 Slimline Repeater and mount on the front panel instead of the options tray. Two versions are available: T708-91 230V/50Hz mains supply T708-92 120V/60Hz mains supply. The units are electrically the same as (although mechanically different from) the T708-01 and T708-02 respectively.
  • Page 280 T800-06 External Frequency Reference Kit The T800-06 kit features an additional D-range plug which incorporates a miniature RF connector to carry an externally generated 12.8MHz reference signal into a T800 mod- ule. This enables the use of very high stability external reference oscillators for special applications.
  • Page 281 The T802-00 is a microprocessor controlled remote monitor unit designed for use with Tait base station equipment. Each remote base requires one T802-00 which communi- cates via its integral modem with a centrally located PC based controller. The PC con- troller runs software to convert the raw data from the T802-00 into a user friendly form.
  • Page 282 T802-10 RF Splitter The T802-10 RF splitters are used to take attenuated RF from the transmitter to the T802–00 where it is mixed onto the receiver frequency by the shift mixer. This RF is then inserted via another splitter into the receiver. Each T802-10 kit contains 2 identical RF splitter modules.
  • Page 283 T808 Mains Power Supply The T808 is a switching power supply capable of supplying up to 25A at 11-14V DC. It requires a mains supply of 230V/50Hz or 115V/60Hz (nominal values) which can be internally selected with a switch or wire links. The T808 is designed to power T800 series 100W transmitters (plus receivers, etc.) and comes complete with a guide to mount in a standard 60mm rack frame assembly.
  • Page 284 31/01/96 Copyright TEL...

This manual is also suitable for:

T830 25wT830 50w

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