MT-3/MT-4 RADIO SYSTEMS UHF AMPLIFIER INSTRUCTION MANUAL UT-3 / UT-4 406 - 470 MHz Covers models: UT-3/400 Amplifier UT-4/400 Amplifier Copyright © 1998 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. DE™ is a registered trademark of Daniels Electronic Ltd.
Reviewed By: Quality Assurance: Larry Freeman 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 1.1 Introduction............................................................................. 1-1 1.2 Performance Specification ............................................................ 1-1 2 THEORY OF OPERATION................................................................... 2-1 2.1 Amplifier Operation.................................................................... 2-1 2.
5 PARTS LISTS...................................................................................5-1 5.1 UT-4/400 UHF Amplifier Electrical Parts List......................................5-1 5.2 UT-4/400 UHF Amplifier Mechanical Parts List ...................................5-4 5.3 UT-3/400 UHF Low Pass Filter Electrical Parts List ..............................5-4 6 REVISION HISTORY..........................................................................
1 GENERAL 1.1 Introduction The UT-3/400 Amplifier provides the final stage of RF amplification and filtering for the entire UHF Transmitter UT-3 406 -512 MHz family. The amplifier has four distinct frequency ranges: 406 to 430 MHz, 450 to 470 MHz, 470 to 490 MHz and 490 to 512 MHz as well as two distinct output power ranges: 0.5 to 2.0 Watts and 2.0 to 8.0 Watts.
Harmonic Emissions: Less than -80 dBc . Transmitter Mismatch Protection: 20:1 VSWR at all phase angles. Transmitter Alarm: Forward power sense and reverse VSWR; - open collector output (separate or 'OR'ed configuration); -linear output (separate lines only). Operating Temperature Range: -30˚ C to +60˚ C, optional -40˚ C temperature test. Operating Humidity: 95% RH (non-condensing) at +25˚ C. Operating Voltage: +13.8 Vdc Nominal (range +11 to +16 Vdc), +9.5 Vdc Regulated. Transmit Current: 0.
2 THEORY OF OPERATION 2.1 Amplifier Operation The operation of the UT-3/400 Amplifier varies slightly according to whether the amplifier is a low power (0.5-2.0 W) or a high power (2.0-8.0 W) version. The low power amplifier does not use transistor Q1 to boost the output power; consequently, it does not require the +13.8 Vdc supply. In both versions the power control circuitry monitors the RF output power of amplifier U4 and keeps the power constant.
2.2 Power Requirements Typical current requirements for the UT-3/400 Amplifier at different power levels are given in the Table 2-1 below. The current drawn from the +9.5 Vdc supply should never exceed 1.2 Amps and the current drawn from the +13.8 Vdc supply should never exceed 1.5 Amps. Table 2-1 UT-3/400 Amplifier Current Consumption 0.5 to 2.0 Watt Amplifier Output +9.5 Vdc Power Supply Current 0.5 W 0.65 A 1.0 W 0.87 A 1.5 W 1.02 A 2.0 W 1.17 A 2.0 to 8.0 Watt Amplifier Output +9.
2.4 Power Control Circuitry The UT-3/400 Amplifier employs a closed loop power control which uses a sample of the forward RF power to control the gain of RF amplifier U4. Op-amp U1b compares the sampled RF voltage to the output power setpoint and generates an error signal which Q3 uses to control the voltage on U4's gain control pin. The output power setpoint is determined by R7, the Output Power Adjust potentiometer.
2.5.2 VSWR Sense The VSWR sense circuitry uses directional coupler TL4 to sample some of the power reflected from the antenna terminal. The reflected power is rectified by diode D7 and capacitor C33 and then amplified by op-amp U2b. Op-amp U2b's amplification is controlled by R36, the VSWR Alarm Adjust potentiometer.
3 UT-3/400 AMPLIFIER ALIGNMENT 3.1 General Connections to the power supply, alarm and transmit enable lines (ENA), are clearly marked on the amplifier case. The amplifier is enabled when the enable line (ENA) is grounded. If the amplifier is installed in the transmitter, alignment is simplified by using an SR-3 Subrack, SM-3 System Monitor, and RF extender cable to provide transmitter power and signal interconnection (see the Transmitter Main Board Manual for details).
It is recommended that the radio communications test set be frequency locked to an external reference (WWVH, GPS, Loran C) so that the high stability oscillator may be accurately set to within its ±1 ppm frequency tolerance. 3.4 Printed Circuitboard Numbering Convention To ease troubleshooting and maintenance procedures, Daniels Electronics Limited has adopted a printed circuitboard (PCB) numbering convention in which the last two digits of the circuitboard number represent the circuitboard version.
amplifier's output power level, alarm levels, and tuning for the transistor matching circuit in the high power version can be set without detaching the amplifier from the transmitter board. However, if the output power alarm or the Antenna VSWR alarm output configuration requires changing, the UT-3/400 Amplifier must be detached from the MT-3 Transmitter Board. Refer to section 4 page 2 "UT-3/400 Amplifier Component Layout" for the location of solder jumpers JU1 to JU5. 3.6.
3 Turn on the power to the transmitter. 4 For high power amplifier units, follow steps 5 to 7 below. For low power amplifiers, skip to the Output Power Alarm procedure. 5 Tune the output matching capacitor for maximum output power. approximately 8 Watts. 6 For single frequency applications, tune the input matching capacitor so that +9.5 Vdc current is minimized without sacrificing output power.
4 Adjust R21, the output power alarm adjustment, so that the voltmeter indicates +7.5 Vdc for full transmitter output power. 5 Turn R7, the output power adjustment, fully counterclockwise. The voltmeter should read approximately +3 Vdc. 6 Disconnect the voltmeter. 3.6.2.3 1 Output Power Turn R7, the output power adjustment, clockwise to the desired transmitter output power. 3.6.2.
4 Adjust R36, the VSWR alarm adjustment, so that the voltmeter indicates +5 Vdc for a 3:1 mismatch. 5 Put the 50 ohm load back on again. The voltmeter should read approximately 0 Vdc. 6 Disconnect the voltmeter. 3.6.2.5 Antenna VSWR Overload 1 Disconnect the radio communications test set and so that the amplifier is terminated with an open circuit. 2 Monitor the current from the +9.5 Vdc supply. 3 Adjust R38, the VSWR overload adjustment, clockwise until a noticeable drop in the +9.
4 ILLUSTRATIONS AND SCHEMATIC DIAGRAMS This Page Intentionally Left Blank DANIELS DE ELECTRONICS 4-1 UHF Amplifier Instruction Manual UT-3 406 - 512 MHz
4.1 UT-3/UT-4 UHF Amplifier Component Layout 16 AWG, RED WIRE U4 SEL FB1 + C21 C22 C20 4u7 100n 10n C23 1n FB2 R15 L8 100R 150n L9 C38 + 10u C4 18n C9 1n C6 18n C7 4u7 C8 4u7 L1 Q1 MRF641 L3 C19 L10 L7 180n 180n R1 DIRECTIONAL SEL SEL COUPLER L5 R2 R3 C1 C3 D2 L2 L4 150n SEL SEL 18n 18n 1N5402 TL2 180n 180n C2 D2 18n D3 C5 C25 R14 1N5402 18n D5 C17 BYD17J SEL C24 TL1 49R9 MMBD701 0.6p-3.5p Q2 0.6p-3.
4.2 UT-3/UT-4 UHF Amplifier Schematic Diagram TL2 COAX CONFORMABLE +13.8 VDC +13.8 VDC FIL3 LPF +13.8 VDC C20* 4.7uF U4 MHW707-SEL 2 dB PAD FIL2 LPF S R4 49k9 MHW 707 TL1* DIRECTIONAL COUPLER TO ALL SWITCHED +9.5V D2 IN5402 D L1 180nH TL3 DIRECTIONAL COUPLER C16* 15pF L7* 0.75 TURN Q1* MRF641 + C1 18nF L3 180nH L4 180nH C3 18nF C38 10uF C6 18nF C7 4.7uF + L8* 150nH C8 4.7uF C17* 0.6-3.5pF R14* 49R9 L5 150nH C18* SEL C24* 0.6-3.5pF R17 49R9 C25* SEL R32 49R9 FB1* +9.
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4.3 UT-3/400 UHF Lowpass Filter Component Layout 4.
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5 PARTS LISTS 5.1 UT-3 / UT4 UHF Amplifier Electrical Parts List NOTE: Reference Designators labeled with an asterisk (*) are used only in 2.0 - 8.0 Watts amplifiers. Ref Desig Description Part No. C1-C6 C7, C8 C9 C10 C11, C12 C13 C14* C15* C16* C17* C18* C19* C19* C19* C19* C20* C21* C22* C23* C24* C25* C25* C25* C25* C26* C26* C26* C26* C27 C28 C29 C30-C32 C33 C34 C35 C36 C37 C38 CAP., SM, 18nF CER, 1206, X7R CAP., SM, 4.7µF TANT., 10%, 16V CAP., SM, 1nF CER, 1206, C0G CAP.
Ref Desig Description Part No. FB1* FB2* FIL1, 2 FIL3* FIL4, 5 FERRITE BEAD, 64 MIX 3x3.5 mm OD FERRITE BEAD, 64 MIX 3x3.5 mm OD FILTER, EMI PI/5500pF, 8-32 UNC FILTER, EMI PI/5500pF, 8-32 UNC FILTER, EMI PI/5500pF, 8-32 UNC 1210-64030350 1210-64030350 1302-P552D10D 1302-P552D10D 1302-P552D10D J1 J2 CONN., SMB, JACK,2 HOLE FLANGE CONNECTOR, N JACK PANEL MNT, C/SNK 5120-J2SC01BG 5184-10923011 L1-L4 L5 L6* L7* L8* L9* L10* L11, L12 INDUCTOR, SM, 180nH 20%, 1812 CHOKE RF/MOLDED, 150nH 10%, 0.
R30 R31 Ref Desig RES., SM, 49k9 1206, 1%, 100ppm RES., SM, 10k0 1206, 1%, 100ppm 1150-4B4992FP 1150-4B1002FP Description Part No. R32 R33 R33 R34 R34 R35 R36 R37 R38 R39 R40 R41 R42 R43 R44 RES., SM, 49R9 1206, 1%, 100ppm RES., SM, 4k53 1206, 1%, 100ppm RES., SM, 49k9 1206, 1%, 100ppm RES., SM, 49k9 1206, 1%, 100ppm RES., SM, 39k2 1206, 1%, 100ppm RES., SM, 10k0 1206, 1%, 100ppm POT., SM, 50k 12 TURN, SIDE ADJUST RES., SM, 1k00 1206, 1%, 100ppm POT., SM, 50k 12 TURN, SIDE ADJUST RES.
5.2 UT-3/400 UHF Amplifier Mechanical Parts List Description Part No. Qty. CAP SCREW, 8-32 X 1/4, HEX BUTTON - 9/64 CASE, MT-3 VHF/UHF AMPLIFIER, ALUMINUM 5806-832BH04S 3702-66102130 1 1 (0.5 - 2.0 Watts) HEATSHRINK, 1/8" DIA, RED, 1" LENGTH CONSUMABLE 1 (2.0 - 8.0 Watts) INSULATOR, THERM. COND. TO-220 5622-1T220701 1 LABEL, IDENTIFICATION/TEST, FOIL LID, CASE MT-3 AMPLIFIER, ALUMINUM CONSUMABLE 3702-66102151 1 1 SCREW, M2 X 6, PAN/PHIL., A2 SCREW, M2 X 4, PAN/PHIL., A2 SCREW, M2.
6 REVISION HISTORY ISSUE DATE REVISION 1 First Issue.
ISSUE DATE REVISION DANIELS DEELECTRONICS 6-2 UHF Amplifier Instruction Manual UT-3 406 - 512 MHz
