MT-4 RADIO SYSTEMS P25 DIGITAL VHF BASE TRANSMITTER INSTRUCTION MANUAL VT-4B 136 - 174 MHz Covers models: VT-4B140-00-000, VT-4B160-00-000 VT-4B140-01-000, VT-4B160-01-000 Copyright © 2000 Daniels Electronics Ltd. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written consent of Daniels Electronics Ltd.
Reviewed By: Quality Assurance: Claudia Boorman Name Signature _________________ Date NOTE: The user's authority to operate this equipment could be revoked through any changes or modifications not expressly approved by Daniels Electronics Ltd. The design of this equipment is subject to change due to continuous development. This equipment may incorporate minor changes in detail from the information contained in this manual.
TABLE OF CONTENTS Page 1 GENERAL..................................................................................... 1.1 Introduction.............................................................................. 1.2 Manual Organization.................................................................... 1.3 VT-4B 136 - 174 MHz Transmitter Family Models ................................ 1.4 Performance Specifications ............................................................ 1.4.1 General..................
2.5.1.2 Transmitter Deviation Balance Adjustment ..................................... 2-7 2.5.1.3 Transmitter Deviation Limit Adjustment ........................................ 2-7 2.5.2 Amplifier Alignment.................................................................. 2-8 2.5.3 Frequency Change.................................................................... 2-8 2.6 Recommended Test Equipment List................................................... 2-8 2.7 Repair Note................................
1 1.1 GENERAL Introduction The VT-4B P25 Digital Base Transmitter is capable of operating in 12.5 kHz / 15 kHz or 25 kHz / 30 kHz channels. The transmitter operates continuous duty in the 136 to 174 MHz frequency band and its output power is continuously adjustable from 2.0 to 8.0 Watts. A modular design allows each of the transmitter's modules: Transmitter Board, VT-3/150 Amplifier to be individually assembled and tested.
1.4 Performance Specifications 1.4.1 General The following is a general set of specifications for the generic VT-4/150 transmitter. Additional specifications, specific to individual modules may be found in their respective sub manuals. Type: MT-4 Series Transmitter. Family: VT-4B 136 - 174 MHz. Compatibility: MT-2 Series and MT-3 Series Radio Systems, Project 25 interoperable. Frequency Range: 136 to 150 MHz., 150 to 174 MHz RF Power Output: 2.0 to 8.0 W Continuous.
Frequency Stability: Standard: ±2.5 ppm, -30°C to +60°C. Channel Selection: In 5.0 or 6.25 kHz increments selected with Radio Programming Software package. Standby Current: 100 mA DOC Type Approval: TBA FCC Type Acceptance: TBA 1.4.2 Audio Specifications Audio Input: Unbalanced, 600 or 47k5 ohm selectable input impedance. Audio Response: Pre-emphasis (6 dB per octave); +0.5 to -2.0 dB from 300 Hz to 3 kHz; Audio Deviation Limiting: +/- 2.5 kHz, +/- 5.
connection made through mated "mother board" assembly of the repeater subrack. Type F standard connector complies with DIN 41612 Level 2 (200 mating cycles, 4 day 10 ppm SO2 gas test with no functional impairment and no change in contact resistance).
2 2.1 THEORY OF OPERATION Transmitter Operation A VT-4B Base Transmitter is constructed using two primary modules: the MT-4 Digital Base Transmitter Main Board and the VT-4 Amplifier Board. The Main Board supports two plug in modules: the Transmitter Controller Board and the Transmitter RF Board. The MT-4 Digital Base Transmitter Main Board receives its audio input through the balanced input on connector P1, from an external microphone input on connector P1, or from a front panel microphone.
2.2.1 Transmitter Wide Options Several options may be set which affect the operation of the Transmitter on a global basis. 2.2.1.1 Disable Front Panel Led This option is not currently used. In future models it will allow the front panel led to be disabled during normal repeater operation in order to save current. 2.2.1.2 Secure Hardware Equipped This setting is used to allow the installation of an encryption module 2.2.1.3 Allow Emergency Transmissions This option is not currently used. 2.2.1.
2.2.2 Channel Wide Settings There are currently 32 channels, which may be individually programmed for various parameters. 2.2.2.1 Frequency The transmitter’s frequency may be set here. The Radio Programming Software will only allow frequencies within the operation band (set in the Transmitter Wide options above) to be entered. 2.2.2.2 Voice/Signal Type Allowed values are PROJECT 25, ANALOG and MIXED MODE.
2.2.2.7 DCS Invert This option allows the DCS code to have its phase inverted by 180 degrees, which is used to compensate for phase inversions introduced in the signal path. 2.2.2.8 Enable Turn Off Code This option enables a DCS Turn Off Code to be sent at the end of a transmission. The Turn Off Code signals to the receiving radio that the transmission is ending, allowing it to mute more quickly. 2.2.2.9 Transmitter Power This option is not currently used. 2.2.2.
2.2.2.15 NAC Transmitter Code This field allows a Network Access Code to be defined for the transmitter. 2.2.2.16 NAC Transmitter This option is not used for the Base Transmitter. 2.3 Transmitter Programming using Motorola Radio Service Software Daniels’ Radio Programming Software package is not yet ready to program the transmitter module.
2.4 Secure Communications The transmitter is capable of sending secure communications if a DES-OFB encryption module is installed. To transmit a secure signal, the transmitter must be programmed with the correct encryption key using a Motorola KVL keyloader in conjunction with a Daniels Keyloader Cable. Consult the instructions for the Keyloader for details on loading a key. A loaded key may be cleared by pulling first the CLEAR KEYS 1* then the CLEAR KEYS 2* inputs to ground about 500 ms apart.
by the frequency counter matches the test frequency displayed on the screen to within +/- 150 Hz. Click on the "UPDATE SOFTPOT" button to save the setting in the transmitter's non-volatile memory. This completes the adjustment of the reference oscillator. Leave the RF Board disconnected from the amplifier module and continue with the next alignment procedure. 2.5.1.
2.5.2 Amplifier Alignment The RF power output of the amplifier is set to its rated value of 2.0 Watts or 8.0 Watts at the factory. This should not require adjustment under normal circumstances. However, should it be necessary to correct the output power, follow the procedure in the Amplifier Manual. Adjustment may also be required when the transmitter's operating frequency is changed.
2.7 Repair Note The transmitter is mainly made up of surface mount devices that should not be removed or replaced using an ordinary soldering iron. Removal and replacement of surface mount components should be performed only with specifically designed surface mount rework and repair stations complete with ElectroStatic Discharge (ESD) protection. When removing Surface Mount Solder Jumpers, it is recommended to use solder braid in place of manual vacuum type desoldering tools when removing jumpers.
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3 ILLUSTRATIONS 3.1 Digital Base Transmitter Front Panel P25 BASE TX FACTORY SET OPERATING FREQUENCY FREQUENCY (MHz) TRANSMIT LED 165.
3.2 Digital Base Transmitter Case - Exploded View B A B B A B 3 FINGER GASKET (2) A A xT4DBM2 Transmitter Case Removal: 1. Remove Screws A (four M3x8mm). 2. Remove Screws B (four M5x8mm). 3. Hold Front Panel and Pull Case.
3.3 Digital Base Transmitter Block Diagram FRONT PANEL KEY TX +9.5VDC +9.5V OUTPUT B6 NORM +9.5 VDC SW1 KEY TX J3 RJ45 CONNECTOR LH_DATA SB9600_BUSY Z6 KEY LOAD* RF BOARD KEY FAIL* 20 OPTB+/VPP B2 TO ALL +13.8 V SUPPLY POINTS +13.8 VDC CONTROLLER / RF BOARDS INTERFACE BUS +9.5 VDC +9.
3.4 Digital Base Transmitter Module Schematic Diagram MAIN BOARD P1 B2 LPF1 LPF B2 TO ALL 13.8V SUPPLY POINTS C1 10uF +13.8V P1 P1 Z2 B6 9.5V C2 1.0uF LPF2 LPF Z2 C17 100nF B6 P1 Z6 Z6 3 Sd 4 Gnd 5V Tap 6 FB 7 WIRES SOLDERED FROM RF AMP PCB TO J1 LPF26 LPF R1 82K5 D8 BYD17J C13 10nF 1 J11 SMB J1 8.9V C15 10uF RF BOARD INTERFACE C16 1.0uF C14 4.7uF 2 MATES WITH RF BOARD J1 J1 TO ALL 9.5V SUPPLY POINTS J5 2 1 (SW1 ON FRONT PANEL) 4 KEY TX LPF4 LPF Vout 1 Sense 2 9.
3.5 Digital Base Transmitter Main Board Component Layout (Bottom) GND J11 RF BOARD GND 8.9V A1 50072-01 A7 Secure Digital Transmitter Board + J4 + B1 C15 10µF C16 1.0µF B8 LPF26 SW1 20 2 J5 LED1 1 ENA* 9.5V 13.8V D DANIELS DE ELECTRONICS P25 Digital Base Transmitter Instruction Manual DANIELS ELECTRONICS xT4DBM5 VICTORIA B.C . TITLE.: SECURE DIGITAL TX MAIN BOTTOM COMPONENT LAYOUT DATE.: 3 MARCH 1999 BOARD No.
3.6 Digital Base Transmitter Main Board Component Layout (Top) 13.8V 9.5V C2 LPF2 ENA* C1 LPF1 10µF 1.0µF 2 C4 1.
4 PARTS LIST 4.1 4.1.1 P25 Base Transmitter Main Board Parts List P25 Base Transmitter Main Board Electrical Parts List Ref Desig Description Part No. C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 CAP., SM, 10uF TANT., 20%, 35V CAP., SM, 1.0uF TANT., 20%, 35V CAP., SM, 10uF TANT., 20%, 35V CAP., SM, 1.0uF TANT., 20%, 35V CAP., SM, 10nF CER,0805,X7R,50V CAP., SM, 100nF CER., 0805, X7R, 50V CAP., SM, 100nF CER., 0805, X7R, 50V CAP., SM, 100nF CER., 0805, X7R, 50V CAP., SM, 100nF CER.
Ref Desig J11 LED1 Description CONN., SMB JACK, SM, STRHT. LED, GREEN, BILEVEL,RA PC MNT Part No.
Ref Desig Description Part No. R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 R27 R28 R29 R30 RES., SM, 1K0 1206, 1%,100ppm RES., SM, 1K0 1206, 1%,100ppm RES., SM, 1K0 1206, 1%,100ppm RES., SM, 825R0 1206, 1%,100ppm RES., SM, 825R0 1206, 1%,100ppm RES., SM, 10K0 0805, 1%,100ppm RES., SM, 1K0 1206, 1%,100ppm RES., SM, 1K0 1206, 1%,100ppm RES., SM, 0R0 ZERO OHM JUMPER,1206 RES., SM, 0R0 ZERO OHM JUMPER,1206 RES., SM, 0R0 ZERO OHM JUMPER,1206 RES., SM, 0R0 ZERO OHM JUMPER,1206 RES.
SCREW, M2.5 x 12 FLAT/PHIL, A2 SCREW, M3 X 6, OVAL C/S/PHIL, Ni SCREW, M3 X 6 PAN/PHIL, A2 SCREW, M3 x 8,OVAL C/S/PHIL,A2 SCREW, M5 X 8 FLAT/PHIL, A2 5812-2M5FP12S 5812-3M0VP06N 5812-3M0PP06S 5812-3M0VP08S 5812-5M0FP08S 9 2 4 4 4 SHIELD, RF BOARD, SEC DIG TX SHIELD, CONTROLLER BOARD, SEC DIG TX TBA TBA 1 1 SCREW, M2.5 x 3 FLAT/PHIL, A2 TBA 4 SECURE DIGITAL TX FRONT PANEL TBA 1 SLOTTED STANDOFF, 5mmOD, 6.5mm L,M2.5 TBA 6 STANDOFF, 5mmOD, 6mm L,M2.5 TBA 4 WIRE, TFE/STRAND.
5 REVISION HISTORY ISSUE DATE DESCRIPTION AND (REASON) 1 • Preliminary July 00 DANIELS DEELECTRONICS VT-4B150 VHF Project 25 Digital Base Transmitter Instruction Manual 5-1
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