TERMALINE® LOAD RESISTOR SERIES 8920 MODELS: 8921 8922 8926 8927 8928 8922D 8926D 8927D ©Copyright 2008 by Bird Electronic Corporation Instruction Book Part Number 920-8920S Rev.
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Safety Precautions The following are general safety precautions that are not necessarily related to any specific part or procedure, and do not necessarily appear elsewhere in this publication. These precautions must be thoroughly understood and apply to all phases of operation and maintenance. WARNING Keep Away From Live Circuits Operating Personnel must at all times observe general safety precautions.
This symbol indicates that a shock hazard exists if the precautions in the instruction manual are not follwed. The caution symbol appears on the equipment indicating there is important information in the instruction manual regarding that particular area. This symbol indicates that the unit radiates heat and should not be touched while hot. Note: Calls attention to supplemental information.
Safety Statements USAGE ANY USE OF THIS INSTRUMENT IN A MANNER NOT SPECIFIED BY THE MANUFACTURER MAY IMPAIR THE INSTRUMENT’S SAFETY PROTECTION. USO EL USO DE ESTE INSTRUMENTO DE MANERA NO ESPECIFICADA POR EL FABRICANTE, PUEDE ANULAR LA PROTECCIÓN DE SEGURIDAD DEL INSTRUMENTO. BENUTZUNG WIRD DAS GERÄT AUF ANDERE WEISE VERWENDET ALS VOM HERSTELLER BESCHRIEBEN, KANN DIE GERÄTESICHERHEIT BEEINTRÄCHTIGT WERDEN.
SERVICE SERVICING INSTRUCTIONS ARE FOR USE BY SERVICE - TRAINED PERSONNEL ONLY. TO AVOID DANGEROUS ELECTRIC SHOCK, DO NOT PERFORM ANY SERVICING UNLESS QUALIFIED TO DO SO. SERVICIO LAS INSTRUCCIONES DE SERVICIO SON PARA USO EXCLUSIVO DEL PERSONAL DE SERVICIO CAPACITADO. PARA EVITAR EL PELIGRO DE DESCARGAS ELÉCTRICAS, NO REALICE NINGÚN SERVICIO A MENOS QUE ESTÉ CAPACITADO PARA HACERIO. WARTUNG ANWEISUNGEN FÜR DIE WARTUNG DES GERÄTES GELTEN NUR FÜR GESCHULTES FACHPERSONAL.
CONNECT INTERLOCK TO TRANSMITTER/GENERATOR/AMPLIFIER BEFORE OPERATING. BRANCHER LE VERROUILLAGE À L’ÉMETTEUR/GÉNÉRATEUR/ AMPLIFICATEUR AVANT EMPLOI. CONECTE EL INTERBLOQUEO AL TRANSMISOR/GENERADOR/ AMPLIFICADOR ANTES DE LA OPERACION. VOR INBETRIEBNAHME VERRIEGELUNG AM SENDER/GENERATOR/ VERSTÄRKER ANSCHLIESSEN. PRIMA DI METTERE IN FUNZIONE L’APPARECCHIO, COLLEGARE IL DISPOSITIVO DI BLOCCO AL TRASMETTITORE/GENERATORE/ AMPLIFICATORE.
About This Manual This manual covers the operating and maintenance instructions for the following models: 8921 8922 8926 8927 8928 8922D 8926D 8927D Changes to this Manual We have made every effort to ensure this manual is accurate. If you discover any errors, or if you have suggestions for improving this manual, please send your comments to our Solon, Ohio factory. This manual may be periodically updated.
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Table of Contents Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i Safety Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i Warning Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii Caution Statements . . . . . . . . . . . . . . . . .
Chapter 1 Introduction Bird 8920 Series Loads are portable, 50 ohm, coaxial RF transmission line terminations, designed for frequency ranges of DC – 1 GHz. Bird 8920D Series Loads are identical, except that they are designed for the UHF (470 – 860 MHz) band. They provide accurate, dependable, and low reflection line terminations. Up to 5000 watts of RF power can be dissipated. The load has a coolant chamber surrounded by radiator fins.
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Chapter 2 Theory of Operation Load Resistor Bird 8920 series loads consist of a thin-film-on-ceramic resistor immersed in a dielectric coolant. The resistor, individually selected for its accuracy, is enclosed in a special housing. When surrounded by the coolant, this produces a uniform, practically reflectionless line termination over the specified frequencies. Coolant The load is cooled by natural fluid and air convection currents.
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Chapter 3 Installation This chapter provides information for on-site requirements, unpacking, inspection, and preparing the load for use. Unpacking and Inspection 1. 2. 3. Carefully inspect shipping container for signs of damage. Do one of the following: • If the shipping container is damaged, do not unpack the unit. Immediately notify the shipping carrier and Bird Electronic Corporation. • If the shipping container is not damaged, unpack the unit. Save shipping materials for repackaging.
Setup Note: Before first using the load, get a resistance baseline for future maintenance. Refer to "DC Resistance" on page 12 for details. 1. 2. Remove the shipping plug. Install the vent plug. Refer to Figure 2 and Figure 3. Installing Thermoswitch Bird 8920 series loads can be equipped with an optional interlock thermoswitch, P/N 8890-008. It is normally closed, opening at 236 °C (457 °F), with a rating of 10A @ 120 VAC and 5A @ 230 VAC.
Figure 4 Thermoswitch Assembly Connecting RF Power After installing the load, the RF transmission line can be attached using standard coaxial line coupling kits. WARNING Never attempt to connect or disconnect RF equipment from the transmission line while RF power is being applied. Leaking RF energy is a potential health hazard. “QC” Connector Coupling • • Use 50 ohm coaxial cable such as RG-218/U or -220/U (-17A or -19A), appropriate for the frequency and power level of operation.
Unflanged Coupling Note: To couple the unflanged connector with an unflanged RF line, use an appropriate coupling kit. Refer to Figure 6 while following the instructions below: 1. Insert the center bullet and bottom it on the midpoint nibs. 2. Position the outer sleeve, with clamping bands, over the input connector. 3. Set the transmission line snugly against the coupling stops. 4. Position the clamping bands evenly about 3/4” from the ends of the sleeve. 5. Tighten the clamping bands.
Chapter 4 Operating Instructions WARNING The vent plug must be used at all times when the unit is operating or cooling. Failure to do so could result in an explosion or severe burns. Normal Operation Bird 8920 series loads have no indicators or operating controls. They require no special operating procedures or surveillance when their performance limits are not exceeded. Follow the instructions for the specific transmitter equipment.
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Chapter 5 Maintenance This chapter covers cleaning, inspection, trouble-shooting, and specifications for the Bird 8920 series loads. WARNING Never attempt to connect or disconnect RF equipment from the transmission line while RF power is being applied. Leaking RF energy is a potential health hazard. WARNING Disconnect the unit from all power sources before servicing. The unit may be energized from multiple sources. The potential for electric shock exists. WARNING Oil is slippery.
Maintenance Cleaning The outside surface of the instrument should be wiped free of dust and dirt when necessary. Excessive dust on the cooling fins will interfere with heat dissipation. Clean the RF connector, both metallic and insulating surfaces, with a dry, non-residue forming solvent. WARNING Oil is slippery. If a leak occurs, be careful not to fall. Inspection Inspect the unit every six months. Check for coolant leakage around the clamping band and the thermoswitch. Also check for corrosion.
Coolant Level Coolant lifetime will vary greatly depending on operating conditions. For heavy use (full RF power for long times, high ambient temperature), check the coolant every 500 hours. If the load has only had light duty (fraction of full power, low ambient temperature), then coolant inspection may only be necessary every 2,000 hours. WARNING Disconnect the unit from all power sources before servicing. The unit may be energized from multiple sources. The potential for electric shock exists.
Load Resistor WARNING Oil is slippery. If a leak occurs, be careful not to fall. 1. 2. 3. Remove the vent plug. Install the shipping plug. Stand the unit on its back with the connector end up. Note: Support the unit to prevent damage to the interlock Note: In this position there is no danger of the coolant pouring out through the resistor hole. 4. 5. 6. Unscrew and remove the clamping band. Lift the load resistor assembly out of the tank. Allow any coolant to drip back into the tank.
Customer Service Any maintenance or service procedure beyond the scope of those in this chapter should be referred to a qualified service center. If you need to return the unit for any reason, request an RMA through the Bird Technologies website (link shown below). All instruments returned must be shipped prepaid and to the attention of the RMA number. Bird Service Center 30303 Aurora Road Cleveland (Solon), Ohio 44139-2794 Fax: (440) 248-5426 E-mail: bsc@bird-technologies.
Specifications Frequency Range 8921-MM-3-150 8922D, 8926D, 8927D All other models 100 - 200 MHz 470 – 860 MHz DC – 1 GHz Power Rating 5000 W continuous duty * Peak Power for Pulse Width 1 µs 10 µs 100 µs 1000 µs 5000 µs 150 kW 115 kW 80 kW 54 kW 22 kW Mode CW, AM, FM, SSB, TV, & Pulsed Digital Systems Impedance, Nominal 8921-MM-3-150 All other models 150 ohms 50 ohms VSWR† 8921-MM-3-150 8922D, 8926D, 8927D All other models‡ 3:1 ± 0.5 1.065 1.
Replacement Parts Description Qty Part Number RF Load Resistor: 8921 8922, 8922D 8926 8926D 8927 8927D 8928 1 Resistor O-Ring 1 5-230 Clamping Band Assembly 1 2430-055 Plug Vent Shipping 1 Interlock Thermoswitch Thermoswitch Body Thermoswitch Jack 1 8890-008 8890-005 2450-018 Radiator Assembly 1 8921-002 Access Plug, 3/4"-14 Hex Socket 1 5020-103 Coolant, 6.
Available “QC” Type Connectors Connector Part Number BNC-Female 4240-125 BNC-Male 4240-132 C-Female 4240-100 C-Male 4240-110 HN-Female 4240-268 HN-Male 4240-278 LC-Female* 4240-031 LC-Male 4240-025 Open Term.
Limited Warranty All products manufactured by Seller are warranted to be free from defects in material and workmanship for a period of one year, unless otherwise specified, from date of shipment and to conform to applicable specifications, drawings, blueprints and/or samples.
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