INSTRUCTION BOOK OPERATING INSTRUCTIONS TERMALINE COAXIAL LOAD RESISTOR MODELS 8251, 8252 & 8255 Electronic Corporation Cleveland (Solon) Ohio USA ÓCopyright 1997 by Bird Electronic Corporation Instruction Book Part Number 920-8251/52/55 Rev.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor
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. Keep Away From Live Circuits Operating Personnel must at all times observe general safety precautions.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor CAUTION Caution notes call attention to a procedure which if not correctly performed, could result in damage to the instrument. This symbol appears on the equipment indicating there is important information in the instruction manual regarding that particular area. + Note: Calls attention to supplemental information.
CAUTION The unit is factory filled to the proper level with 0.8 gallons (3.03 liter) of Bird P/N 5-1070. No other coolant should be used CAUTION Do not leave out the O-Ring seal, P/N 5-504 when interchanging the vent and shipping plugs. Safety Statements USAGE ANY USE OF THIS INSTRUMENT IN A MANNER NOT SPECIFIED BY THE MANUFACTURER MAY IMPAIR THE INSTRUMENT’S SAFETY PROTECTION.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor 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 DESCARGÉAS ELCTRICAS, NO REALICE NINGÚN SERVICIO A MENOS QUE ESTÉ CAPACITADO PARA HACERIO.
About This Manual This instruction book covers models 8251, 8252, and 8255 Termaline Coaxial Resistors. This instruction book is arranged so that essential information on safety is contained in the front of the book. Reading the Safety Precautions Section before operating the equipment is strongly advised. The remainder of this instruction book is divided into Chapters and Sections.
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Table Of Contents Safety Precautions. . . . . . . . . . . . . . . . . . . . . . . i Warning Statements. . . . . . . . . . . . . . . . . . . . . . ii Caution Statements. . . . . . . . . . . . . . . . . . . . . . ii Safety Statements. . . . . . . . . . . . . . . . . . . . . . iii About This Manual. . . . . . . . . . . . . . . . . . . . . . v Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 1 Purpose and Function. . . . . . . . . . . . . . . . . . . . 1 Applications. . . . . . . . . . . . . .
Bird Model 8251/52/55 Termaline Coaxial Load Resistor Operating Instructions. . . . . . . . . . . . . . . . . . . . . 9 Normal Operation. . . . . . . . . . . . . . . . . . . . . . 9 Operation Under Abnormal Conditions. . . . . . . . . . . . . 9 Shutdown. . . . . . . . . . . . . . . . . . . . . . . . . 9 Emergency Shutdown. . . . . . . . . . . . . . . . . . . . 10 Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . 11 Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . 11 Cleaning. . .
Customer Service. . . . . . . . . . . . . . . . . . . . . . . . 17 Sales/Repair Facilities. Sales Facilities. . . . . . . . . . . . . . . . . . . 17 . . . . . . . . . . . . . . . . . . . . . 17 Preparation for Shipment. . . . . . . . . . . . . . . . . . . . . 17 Replacement Parts List.. . . . . . . . . . . . . . . . . . . . .
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Chapter 1 Introduction This publication refers to the Termaline Coaxial Load Resistor Models 8251, 8252, and 8255. The differences between models are listed in the specifications. All models will generally be referred to as a load thoughout this manual. The information in this instruction book pertains to all models except noted differences referred to in the text. Purpose and Function The Bird Termaline Coaxial Load Resistors are portable, general purpose 50 ohm coaxial transmission line terminations.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor Power and Utility Requirements These loads are passive devices that are self-contained and require only RF input to function. Environmental Requirements These loads should be operated in a dust and vibration free environment. Allow at least 6 inches (153 mm) of clearance around the units to permit adequate heat dissipation.
Introduction Specifications Impedance, Nominal VSWR: Models 8251/52 50 ohms 1.10 max. dc to 1000 MHz 1.25 max. 1000-2000 MHz Model 8251 1.30 max. 2000-2400 MHz Model 8255 1.25 to 1.0 max.
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Chapter 2 Theory of Operation These loads consist essentially of a carbon film resistor on a ceramic substrate immersed in a dielectric coolant. The resistor, individually selected for its accuracy, is enclosed in a special exponentially tapered housing. This provides a linear reduction in surge impedance directly proportional to the distance along the resistor.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor Figure 1 Shipping Plug O-ring seal Figure 2 Vent Plug O-Ring Seal 6
Chapter 3 Installation CAUTION This equipment is designed for operation in a horizontal position only, with mounting brackets down. Do not operate in any other manner. The Models 8251, 8252, and 8255 are to be installed, and operated, in a horizontal position. The unit is shipped horizontal, and normally stands on its base brackets. The load may be used for portable operation and stand free, or it may be secured to a bench top or other flat surface for a fixed installation.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor Connecting to Transmitter Models 8251 & 8255 Connect the load to the transmitting equipment under test with 50 ohm coaxial cable (RG-8A/U, RG-9/U, RG-213/U or equivalent) and a Male LC type plug. The Male LC plug will mate with the RF input connector of the load. After the transmitter has been connected to the load, proceed according to the transmitter manufacturer’s instructions.
Chapter 4 Operating Instructions Normal Operation CAUTION Do not operate this equipment over the rated 1000 watts continuously. Damage to the resistive element will result. These loads have no indicators or operating controls, therefore require no special operating procedures or surveillance when the stated performance limits are not exceeded. Follow the instructions pertaining to the specific transmitting equipment.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor Emergency Shutdown 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. Turn off RF power at the source.
Chapter 5 Maintenance Troubleshooting For corrections requiring repair or replacement or components, refer to the appropriate section for your specific model.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor Inspection With the rugged and simple construction of the loads, periodic inspection will be necessary at only about six month intervals. Inspection should include the items listed below: s Oil Leakage - check for coolant oil leaking around the radiator tank, particularly at the front and back around the underside of the clamping band.
Maintenance DC Resistance Measurement Preparation and Tools Required Be sure that the vent plug is installed. Preparation: s Tools: Common hand tools s Ohmmeter with an accuracy of ± 1% at 50 ohms. s Temperature of the load between 20°C to 25°C (68°F to 77°F) VSWR and RF Impedance are the true benchmark of a quality dummy load. Accurate measurement of the dc resistance between the inner and outer conductors of the RF input connector will provide a good check of the condition of the load resistor.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor These tests are by no means a necessity to the operation of the load but merely guidelines for the users information and advisement. Disassembly Figure 3 Measuring DC Resistance 50.0 There are no special techniques required for the repair or replacement of components in these Termaline Load Resistors. Tools Required Models 8251 and 8255 - A screwdriver and a small wrench are they only tools needed for these models.
Maintenance Rear Seal and Coolant Before any disassembly of the rear of the load, if the coolant has not already been drained from the tank, stand the radiator on end with the connector pointed down. 1. Unscrew the four 10-32 screws at the corners of the guard cover. 2. Unscrew the tube nut from the tank nozzle, using a small wrench if necessary, and pull the nozzle free. 3. Loosen the clamp screw with a screwdriver from the bottom of the V-band, same type as at the front, and remove the V-band clamp. 4.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor 3. Loosen the 10-32 x 1-1/2 inch screw on the clamping band until the band is free. Remove the band. 4. Grasp the RF connector and slowly lift the load resistor assembly out of the radiator tank to allow the excess coolant to drip back in. 5. Before replacing the load assembly (Model 8251, P/N 8890-050; Model 8252, P/N 8891-050) check the O-Ring seal to be sure it is properly placed and is in good condition.
Maintenance Storage No special preparations for storage are necessary other than to cover the equipment to keep out dust and dirt. Store the unit in a dry and dust-free environment where the ambient temperature will remain within the -40°C to +45°C (-40°F to +113°F) working range of the load. Customer Service Any maintenance or service beyond the scope of those provided in this section should be referred to a qualified service center.
Bird Model 8251/52/55 Termaline Coaxial Load Resistor Replacement Parts List Qty. 1 Description Part Number RF Section Assembly Model 82514/8255 Model 8252 8890-050 8891-050 Radiator Assembly Model 8251 Model 8252 Model 8255 2430-123 2430-146 2430-153 Diaphragm Cover Guard Model 8251 Model 8252 Model 8255 2430-078 2430-078-1 2430-078-2 0.8 gals (3.
Limited Warranty All products manufactured by Seller are warranted to be free from defects in material and workmanship for a period of one (1) year, unless otherwise specified, from date of shipment and to conform to applicable specifications, drawings, blueprints and/or samples.
DECLARATION OF CONFORMITY Manufacturer: Bird Electronic Corporation 30303 Aurora Road Cleveland, Ohio 44139-2794 Product: TERMALINE RF COAXIAL LOAD RESISTOR Models: 8251 8252 8255 The undersigned hereby declares, on behalf of Bird Electronic Corporation of Cleveland, Ohio, that the above-referenced product, to which this declaration relates, is in conformity with the provisions of the following standards; 1. European Standard EN 61010-1:1993 - Safety, Group II.
