UHF 250 WATT POWER AMPLIFIER USER Manual EAGLE WIRELESS INTERNATIONAL 101 Courageous Drive League City, TX 77573 Telephone: (281) 538-6000 Fax: (281) 334-5302 Toll Free: 1-800-628-3910 www.eglw.com sales@eglw.
Preface Preface Scope This user manual contains a high level description of the UHF 250 Watt Power Amplifier as well as a detailed technical description. The scope of this document is to provide the reader with a general understanding, system description, and operation of the UHF 250 Watt Power Amplifier. Section 1 – Presents a general introduction of the UHF 250 Watt Power Amplifier who are familiarizing themselves with the system for the first time.
Preface This publication may have technical inaccuracies or typographical errors. Therefore, the information contained in this manual is subject to change or revision. Changes or revisions will be incorporated in all new editions of the publication. EAGLE WIRELESS INTERNATIONAL, INC. may at any time make improvements and/or changes in product(s) and/or program(s) described in this publication. Products are stocked at the address below.
Preface Cautions & Safety Regulations All RF power transistor and RF termination resistors in this power amplifier contain the toxic substance beryllium oxide. These assemblies are located on the combiner, splitter and power amplifier boards. The fumes and dust of beryllium oxide is also toxic and should only be treated by trained personnel using proper precautions. Federal law and most state laws strictly prohibit disposal of beryllium oxide as a public waste.
Preface expense will be required to take whatever measures may be required to correct the interference. OSHA Safety Standards The United States Department of Labor, through the provisions of the Occupational Safety and Health Act, has established an electromagnetic energy safety standard with applies to the use of this equipment. Proper use of this radio equipment will result in exposure below the OSHA limit.
Preface Integrated Circuit Handling Procedure Care should be taken in handling the circuit boards during installation and service. A number of IC’s (Integrated Circuits) used in the equipment are from the MOS (Metal Oxide Semiconductor) family and are vulnerable to damage from static discharges. Exercise the following precautions when handling these components. − Before handling components, ground yourself by touching a ground rod or the grounded chassis of the equipment momentarily.
Warranty Limited Warranty 1. The product line of paging and mobile equipment, base stations/power amplifiers, receivers, transmitters, security and transmitter control equipment sold by EAGLE WIRELESS INTERNATIONAL, INC. is warranted to the original buyer to meet the then current published specifications, drawings and/or such modifications thereof as Buyer and Seller have agreed to in writing and to be free from defects in workmanship and materials.
Warranty 4. The Seller shall have the right of final determination as to the following: (a) existence of cause and defect, (b) whether adjustment will be allowed, and (c) if allowed, whether adjustment will be by repair or replacement. When adjustment is not allowed, a reasonable charge will be made to the Buyer to cover the Seller’s cost of inspection and handling.
Table of Contents Page Preface ………………………………………………………….. i Limited Warranty ……………………………………………….. vi Introduction ……………………………………………………… 1-1 Features and Specifications…………………………………… 2-1 Major System Components …………………………………… 3-1 Schematics and Appendices.
Introduction Section 1 – Introduction UHF 250 WATT POWER AMPLIFIER Version 3 1-1 07/18/01
Introduction INTRODUCTION EAGLE WIRELESS INTERNATIONAL is pleased to introduce its newest state-ofthe-art technically advanced UHF 250 WATT POWER AMPLIFIER. The UHF 250 WATT POWER AMPLIFIER is fully solid-state design and built with the most advanced and rugged LDMOS power transistors. The POWER AMPLIFIER is designed for continuous duty operation for the paging and link application. The POWER AMPLIFIER has a modular design approach, thus making it easy to operate and maintain the unit.
Features and Specifications Section 2 – Features and Specifications UHF 250 WATT POWER AMPLIFIER Version 3 2-1 07/18/01
Features and Specifications Major features of the UHF 250 Watt Power Amplifier: • Advanced State-of-the-Art Technology • 100% Solid State Continuous Duty • Extensive Front Panel Monitoring & Display • Modular Design • Multi-channel Capability Specification of the UHF 250 Watt Power Amplifier: Frequency Range Power Output RF Input Impedance RF Output Impedance Emission Designators Duty Cycle Primary Power Spurious and Harmonics Adjacent Channel Noise Operating Temperature Operating Humidity Versi
System Components Section 3 – SYSTEM COMPONENTS UHF 250 WATT POWER AMPLIFIER Version 3 3-1 07/18/01
System Components Power Amplifier Configuration The high power amplifier is mounted to the heat sink and is accessible from the backside of the transmitter. All components of the power amplifier are contained in an RF tight enclosure such that only the input and output R.F. coaxial connectors directly penetrate the enclosure. All other penetrations are by filtered feed through which is designed for the R.F. environment. A packaging view of the front and rear of the transmitter is shown in Figures 1 and 2.
LOW PASS FILTER FINAL COMBINER HIGH POWER RF OUTPUT SPLITTER FUSE BOARD DRIVER STAGE PREAMP System Components EXCITER RF INPUT REAR VIEW Figure 2 –Power Amplifier Rear View Version 3 3-3 07/18/01
Version 3 RF Input +12 VDC Display Board Variable +12 VDC Preamp (Optional) 3-4 Control Board Power Sensor 12 VDC DC - DC Converter 1.
System Components Power Amplifier – Control Section The Power Amplifier Control Board provides all of the Power Amplifier control functions necessary to operate any of the Eagle Power Amplifier configurations. PA Control Board DC / DC Converter Drive Stage Voltage Meter Calibration RF Input Calibration FAN Forward Power Calibration Reflected Power Calibration Notch FAN P.A.
System Components Power Amplifier (PA) Control Board 1. The P.A. control board contains all of the hardware and software necessary to provide the following control functions. See Figure 3 for block diagram. a. Variable DC control voltage that drives the P.A. pre-amp to control the output power level of the P.A. b. Bias supply generation for amplifier configurations requiring external bias. c. Monitoring of forward power, reflected power, temperature, VSWR conditions, D.C.
System Components Power Amplifier Control Functions The Power Amplifier Control Functions on the Power Amplifier Control Board are accomplished by the 87C552 master processor located on this board in conjunction with a variety of support circuitry. All of the major power amplifier parameters such as forward and reflected power, heat sink temperature, input drive RF. power, drive stage voltage, and the master power supply voltage are monitored in this board by the processor.
System Components R23 R33 R43 R41 R18 R19 Reset Figure 5 – Transmitter Unit – Power Amplifier Control Board Version 3 3-8 07/18/01
System Components There is, however, a built in delay of two minutes and twenty seconds before the reset condition can occur to allow adequate cooling for an excessively hot ambient condition. The microprocessor also has a software threshold to determine the minimum acceptable output power for a normal transmit condition. When the output power is below this limit a fault indications provided (i.e. low power), but otherwise the amplifier operates normally.
System Components Power Amplifier – RF Section General Description The Power Amplifier circuitry is primarily located in the rear R.F. compartment that provides R.F. shielding for all of the higher power R.F. circuitry. The basic configuration of the Power Amplifier RF Section is shown in Figure 6. This configuration consists of a pre-amp module that drives an intermediate stage amplifier (the driver stage) followed by the high power amplifier stage.
System Components Technical Description The 250-watt version of the 450 MHz power amplifier utilizes a very conservative and simplified design. Like all of the EAGLE power amplifier designs, the exciter output is fed directly through the heat sink and into the RF.
System Components The block diagram of this configuration is also shown below: RF Final 4 Stages Combiner Pre Amp Module Splitter Resistive Pad Exciter Input RF Input Power Sensor RF Output Gain Control And Protection Circuit Thermal Sensor Low Pass Filter Forward And Reflected Power Sensors Figure 8 – Power Amplifier Block Diagram The input from the exciter (approximately 750 milli-watts and 1.0 Watts) is fed directly into the Pre-Amp module.
System Components Figure 9 – RF Final Circuit Board Layout The RF. final Circuit board layout for an individual module is shown in Figure 9. Should the Final Stage ever require replacement, the entire assembly, including the heat spreader, is easily replaced as a subassembly. This combined output signal is fed to a low pass filter, which also incorporates RF detector circuit to determine voltages from the forward and reflected power levels at the output of PA.
System Components Figure 10 – Low Pass Filter Board The final item in the UHF 250 watt power amplifier is the fuse board located in the fuse compartment as shown in Figure 25. This fuse board is utilized in all models of EAGLE power amplifiers up to 500 watts. Therefore, in the 250watt version there are a number of unused fuse locations as shown in Figure 11 below.
System Components Backplane Mother Board The Backplane Mother Board mechanical and electrical details are shown in Figure 12. The schematic for the Mother Board may be found in the Appendix of this manual. There are four separate card slots on the mother board and any of the slots can be used for the PA control board. However, the PA control board is usually installed in last slot on the left.
System Components Power Supply The power supplies are switch mode type supplies. Depending on the requirement, it is capable of supplying 40 amps of DC current at 28 VDC from 115 or 220 VAC line voltage. Each supply is made up of four 28 VDC modules. The modules are assembled in parallels to meet the desired current rating. Each module is individually fused and contains its own temperature controlled fan. The supply is protected against overload and short circuit conditions by foldback current limiting.
System Components 9. All adjustments are factory preset; no field adjustments are necessary. Allow the PA to warm up for a period of 5 minutes before taking measurements. Key the Exciter and check forward Power (factory adjusted), reflected power (close to zero) at the wattmeter and also at the Display meter. Also available at the display panel are: DC supply voltage, Drive voltage and temperature. Rotate the knob on the display panel to read their values.
Appendices Section 4 – Appendices UHF 250 Watt Power Amplifier Version 3 4.
