TERMALINE® LOAD RESISTOR SERIES 8251 ©Copyright 2012 by Bird Electronic Corporation Instruction Book Part Number 920-8251S Rev.
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 followed. 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.
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 instruction book covers the following models: 8251 8251N 8251T-230 8251T-300 8251D 8251D7-16 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. When inquiring about updates to this manual refer to the part number and revision on the title page.
Table of Contents Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i Safety Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i Warning Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii Caution Statements . . . . . . . . . . . . . . . . .
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Chapter 1 Introduction Bird 8251 Series Loads are portable, general purpose 50 ohm coaxial RF transmission line terminations. They are accurate, dependable, and low reflection, dissipating up to 1000 watts of RF power. See Figure 1 on page 1 for frequency ranges. The load has a coolant chamber surrounded by radiator fins. A handle is recessed in the radiator fins. The front and rear fins form mounting flanges which can be used as supports for freestanding use or as brackets for fixed mounting.
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Chapter 2 Theory of Operation Load Resistor Bird 8251 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.
Installing Thermoswitch Bird 8251T loads are identical to the 8251 except for a factory-installed interlock thermoswitch. It is normally closed, opening at either 230 or 300 °F (110 or 149 °C), depending on the model. The terminals are rated for 10A @ 120 Vac and 5A @ 240 Vac. WARNING Disconnect the unit from all power sources before servicing. The unit may be energized from multiple sources. The potential for electric shock exists. CAUTION The thermoswitch has a factory preset temperature adjustment screw.
Using a “QC” Connector Coupling Use a 50 ohm coaxial cable such as RG-218/U or -220/U (-17A or -19A), appropriate for the frequency and power level of operation. Note: Use a cable connector which will mate with the one on the load. Using a 13-30 Coupling Use 50 ohm coaxial cable such as RG-8A/U, RG-9U, RG-213/U, or equivalent with a male 13-30 plug. Using a Swivel Flanged Coupling 1. 2. 3. 4. 5. Insert the center bullet. Push it in until it is fully seated.
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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 OperationNormal Operation Bird 8890 series– 300 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 8251 series loads. Troubleshooting The table below contains troubleshooting information for problems which can occur during normal operation. This manual cannot list all malfunctions that may occur, or their corrective actions. If a problem is not listed or is not corrected by the listed actions, notify a qualified service center.
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. Inspection Inspect the unit every six months. Check for coolant leakage around the clamping band and the thermoswitch. Also check for corrosion.
WARNING Disconnect the unit from all power sources before servicing. The unit may be energized from multiple sources. The potential for electric shock exists. CAUTION Use only Bird coolant, P/N 5-1070, to prevent damage to the load. 1. Remove the load resistor (Refer to “Load Resistor” on page 18). CAUTION Use only Bird coolant, P/N 5-1070, to prevent damage to the load. 2. 3. Inspect the coolant. • The coolant should be clear, with a faint yellow tinge, and have a slightly sweet smell.
Rear Seal If the coolant has not been drained from the load, stand the unit on end with the RF connector down before disassembly. WARNING Disconnect the unit from all power sources before servicing. The unit may be energized from multiple sources. The potential for electric shock exists. 6. 7. Unscrew the four screws at the corners of the guard cover. Unscrew the tube nut from the tank nozzle, using a small wrench if necessary, and pull the nozzle free. 8. Unscrew and remove the clamping band. 9.
Load Resistor 1. 2. 3. 4. 5. 6. Remove the vent plug. Install the shipping plug. Stand the unit on its back, with the RF connector up. Brace the unit to prevent it from tipping over. Unscrew and remove the clamping band. Lift the load resistor assembly out of the tank and allow any coolant to drip back into the tank. Note: The O-Ring should be free of twists and positioned evenly around the flange of the resistor housing. If the O-ring shows signs of deterioration (e.g.
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 8251 8251T 8251N 8251D, 8251D7-16 Power Rating Impedance, Nominal Operating Position VSWR 8251N 8251D, 8251D7-16 8251* 8251T Connectors 8251 8251D 8251D7-16 8251N 8251T Thermoswitch Temperature 8251T-230 8251T-300 Ambient Temperature Cooling Method Dimensions Weight, Nominal Finish DC – 2400 MHz DC – 2000 MHz DC – 1000 MHz 470 – 860 MHz 1000 Watts continuous duty 50 ohms Horizontal only – vent plug up 1.10 1.065 1.10, DC – 1000 MHz 1.20, 1000 – 2000 MHz 1.
Coolant, 0.75 gal (2.84 L) Optional Bullet, 8251D Only 1 1 5-1070-2 4712-020 Available “QC” Type Connectors Connector BNC-Female BNC-Male C-Female C-Male HN-Female HN-Male LC-Female* LC-Male 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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