BIRD 8141,8141-010 Operating 电路图.pdf
INSTRUCTION BOOK OPERATING INSTRUCTIONS TERMLINELOAD RESISTOR MODELS 8141 items supplied; and accessory items. Purpose And Function The Models 8141 and 8141-010 Termaline Load Resistor are portable, general purpose 50 ohm coaxial transmission line terminations. They are self-contained units requiring no outside power source or additional equipment. They provide accurate, dependable, and practically nonreflective termina- tions for testing and adjusting transmitters under nonradi- ating conditions from dc to 2500 MHz. The models are rectangular in shape with transverse cool- ing fins spaced evenly along its entire length. Their short length makes it particularly useful in locations. Also, the ten pounds total weight is a convenience in portable use. Mounting holes are provided, see Chapter 3, Installation. The RF connector, on the front face of the unit, is a Female N similar to UG-58A/U, but is a “Quick-Change” design per- mitting rapid and easy interchange with other AN type con- nectors. Performance Characteristics and Capabilities The loads will absorb and dissipate as heat up to 250W of RF power in continuous duty. It can handle up to 20 percent overload for a maximum of ten minutes overload without damage, provided a half-hour interval is maintained for cooling between power applications. The design of the resis- tor and its impedance matching shell keeps the VSWR be- low 1.1 to 1.0 from dc to 1000 MHz, 1.2 to 1.0 from 1000 to 1800 MHz and 1.3 to 1.0 from 1800 to 2500 MHz. With its “QC” type of connector Model 8141 can be adapted to coaxial cables equipped with any of a variety of standard connec- tors. Dimensions and Weight Consult the Specification Sheet for the size and weight of each load 1 Power and Utility Requirements Other than the RF power input the Models 8141 and 8141- 010 has no need for an external source of power or utility services. Environmental Requirements The loads should be operated in as clean and vibration free an environment as possible. The ambient temperature range should remain within -40C to +45C (-40F to +113F) for proper operation. Items SuppliedThe models area self-contained unit, there are no addi- tional parts other than this instruction book supplied. The load is prefilled at the factory with the proper amount of coolant. Items RequiredNo additional items are required other than a coaxial cable for connecting the RF source to the load. The load is fur- nished with a Female N type connector. The cable should be equipped with a Male N type plug. If the cable has any other type of standard connector, then the load should be or- dered with the appropriate type of mating connector. Tools and Test Equipment Only a screwdriver is needed for disassembling for service. An ohmmeter or resistance bridge with an accuracy of one percent or better at 50 ohms, is useful for checking resistor condition. Specifications Impedance50 ohms nominal VSWR dc-1000 MHz 1000-18000 MHz 1800-2500 MHz 1.1:1 maximum 1.2:1 maximum 1.3:1 maximum ConnectorsBird Quick Change “QC” Female N Normally supplied. Power Range250 W continuous, 300 W intermittent (10 Minutes maximum). Frequency Rangedc to 2500 MHz Dimensions9-9/16”L x 5-15/16”W x 8-1/2”H (243 x 151 x 216 mm) Ambient Temperature40C to +45C (-40F to +113F) Weight10 lb (4.5 kg) Operating PositionHorizontal only FinishLight grey powder coat 2 Bird Model 8141 Termaline Load Resistor Chapter 2 Theory Of Operation GeneralThe Models 8141 and 8141-010 Termaline Load Resistor consists essentially of a cylindrical film type resistor im- mersed in a dielectric coolant. The resistor, individually se- lected for its accuracy, is enclosed in a special tapered housing which provides a linear reduction in surge imped- ance directly proportional to the distance along the resistor. This produces the uniform, practically reflectionless line ter- mination over the stated frequencies of the load. The dielectric coolant is chosen for its desirable electrical properties and thermal characteristics. Cooling of the load is accomplished by natural fluid and air convection. The 0.35 gallon (1.3 liter) of dielectric coolant carries the electrically generated heat from the resistor to the walls of the cylindri- cal cooling tank. The tank is encased in a set of heavy gauge aluminum radiator fins, which are firmly pressed on the cyl- inder. The heat from the dielectric oil is transferred to the surrounding air through the fins by natural convection. A synthetic rubber diaphragm located in the rear dome of the load allows for the expansion of the coolant as the tem- perature rises. 3 4 Bird Model 8141 Termaline Load Resistor Chapter 3 Installation GeneralPosition the Model 8141 and 8141-010 Termaline Load Re- sistor to provide at least six inches of unobstructed space around and above the unit. Place the load to permit the shortest possible cable length between the unit and the transmitting equipment. Operate the load in a horizontal position only, with the han- dle on top. The load may be free-standing or fastened to any convenient flat surface. The front and rear fins are made ex- tra thick and bent outward 90 to form mounting flanges. Fasten the Model 8141 by its mounting brackets with 1/4 machine screws and nuts or No. 12 wood screws if desired. The four 9/32 inch holes in the mounting brackets form a base rectangle of 7-15/32 x 5-1/8 (189.7 x 130.2 mm)for the Model 8141 and 7/13/32” x 5/1/8” (180 x 130.2 mm) for the Model 8141-010. 5 6 Bird Model 8141 Termaline Load Resistor Chapter 4 Operating Instructions Start-upConnect the Models 8141 and 8141-010 Termaline Load Re- sistor to the transmitting equipment under test with 50 ohm coaxial cable such as RG-213/U or equal, equipped with a Male N type plug (UG-21E/U or equal) which mates with the RF input connector of the load. After the transmitter has been connected to the load, proceed according to the transmitter manufacturers instruction. Due to the difference in VSWR between the dummy load and the transmitters antenna, readjustment of the trans- mitter may be required when returning to the original an- tenna. CAUTION Do not operate this equipment over the rated 250 watts continuously. Damage to the resistive element will result. The unit will sustain an intermittent input of 300 W maxi- mum for up to ten minutes with half-hour off intervals be- tween power applications. Normal Operation The loads will dissipate 250W of RF power safely and con- tinuously without an operator in attendance. As stated previously, the load can be overloaded to 300W of RF power for a maximum of ten minutes at a time with an interval of at least a half-hour in between to permit the load to cool off. Because of the additional heat that must be given off by the cooling fins under these conditions, touch the load with caution to avoid the possibility of painful burns. ShutdownThe only way to turn off the equipment is to cut off power from the RF generator. Allow sufficient time for the load to cool down after removing RF power before handling it. 7 Emergency Shutdown WARNING Never attempt to disconnect RF equipment from the transmission line while RF power is being applied. Leaking RF energy is a potential health hazard. Turn off the equipment by removing power from the RF gen- erator. 8 Bird Model 8141 Termaline Load Resistor Chapter 5 Maintenance Troubleshooting For corrections requiring repair or replacement of compo- nents, refer to the appropriate section for your specific model. Cleaning Outside SurfaceThe outside surface of the instrument, especially the cooling fins, should be wiped free of dust and dirt when necessary. Clean the RF input connector with a clean dry cloth. Use an aerosol type non residue forming contact cleaner on the in- accessible portions. Take special care to clean the metallic contact surfaces and exposed face of the teflon insulator. 9 ProblemPossible CauseCorrection Coolant oil leak around clamping band or radiator Clamping bands not tight Tighten slightly with screwdriver Faulty O-ring (front)Replace O-ring Faulty diaphragmReplace diaphragm Overheating of the radiator Transmitter power too high Reduce transmitter power Coolant oil level too low Add more coolant oil to the radiator Accumulation of dirt on cooling fins Clean cooling fins Faulty RF section assembly, check Rdc Replace if needed High or low dc resistance values Loose or faulty RF connector Tighten or replace as needed Faulty RF section assembly Replace if needed Table 1 Troubleshooting Inspection With the rugged and simple construction of loads, periodic inspection will be necessary at only about six month inter- vals. Inspection should include the items listed below: a.Cleanliness - Keep the housing and connector free of grime. b.Oil Leakage - Check for coolant oil seepage from the radiator tank, and particularly at the front and rear near the under side of the clamping band. See Troubleshooting Chart if leakage is observed. Check tightness of the clamping screw. c.Inspect the load for completeness and general condition of the equipment. Preventive Maintenance The load requires only nominal routine care. It is designed to operate for long periods of time, if care is taken not to ex- ceed its power handling capabilities. The principal item of preventive maintenance is cleanliness. Keep the cooling fins clear of accumulated dust and grime. They interfere with the efficient and rapid transfer of heat from the fins to the surrounding air and therefore could cause the unit to overheat. Keep the coolant level up. RF Assembly Test DC ResistanceThe electrical condition of the load resistor itself may be as- certained generally from its dc resistance at room tempera- ture. It must be remembered that VSWR and RF impedance are the prime requisites of a good dummy load, however, occa- sionally checking the dc resistance will offer an indication of a failing load. Normally the dc resistance of the load will be a nominal 50 ohms. Stabilization of the resistive film or temperature can cause a change in the dc resistance. Always check the load when its temperature is between 20 and 25 degrees Celsius. Check and record the dc resistance value of the load before it is put into service. Use a resistance bridge or ohmmeter 10 Bird Model 8141 Termaline Load Resistor with an accuracy of one percent or better at 50 ohms for this purpose. If the load is used frequently, daily to weekly, it would be wise to check the resistance on a monthly schedule. If how- ever, the load is used more infrequently you may want to set up a six month to yearly schedule accordingly. If there is no change or even a slight change in dc resistance there is no cause for alarm, however, if there is a drastic change greater than two ohms, this could be an indication of a fail- ing load. These tests are by no means a dire necessity to the opera- tion of the load but merely guidelines for the users informa- tion and advisement. Disassembly There are no special techniques required for the repair or replacement of components. A screwdriver is the only tool needed. The following paragraphs outline component re- moval. RF Input Connector The input connector is a “Quick-Change” design which per- mits easy interchange with the use of only a screwdriver. This process does not interfere with the essential coaxial continuity of the load resistors RF input or the coolant oil seal. For replacement, proceed as follows: a.Remove the four 8-32 x 5/16 inch pan head machine screws from the corners of the RF connector. b.Pull the connector straight out of its socket. Coolant Oil 1.European Standard EN 61010-1:1993 - Safety, Group II. This standard is in accordance with Council Directive 73/23/EEC and 93/68/EEC. The technical documentation file required by this directive is maintained at the corporate headquarters of Bird Electronic Corporation, 30303 Aurora Road, Cleveland, Ohio. Ken DeVore QA/Metrology Manager Bird Electronic Corporation 16 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. Sellers sole obligation under these war- ranties shall be to issue credit, repair or replace any item or part thereof which is proved to be other than as warranted; no allowance shall be made for any labor charges of Buyer for replacement of parts, adjustment or re- pairs, or any other work, unless such charges are authorized in advance by Seller. If Sellers products are claimed to be defective in material or workmanship or not to conform to specifications, drawings, blueprints and/or samples, Seller shall, upon prompt notice thereof, either examine the products where they are located or issue shipping instructions for return to Seller (transportation-charges prepaid by Buyer). In the event any of our products are proved to be other than as warranted, transportation costs (cheapest way) to and from Sellers plant, will be borne by Seller and reimbursement or credit will be made for amounts so expended by Buyer. Every such claim for breach of these warranties shall be deemed to be waived by Buyer unless made in writing within ten (10) days from the date of discovery of the defect. The above warranties shall not extend to any products or parts thereof which have been subjected to any misuse or neglect, damaged by accident, rendered defective by reason of improper installation or by the performance of repairs or alterations outside of our plant, and shall not apply to any goods or parts thereof furnished by Buyer or acquired from others at Buyers request and/or to Buyers specifications. In addition, Sellers warranties do not extend to the failure of tubes, transistors, fuses and batteries, or to other equipment and parts manufactured by others except to the extent of the original manufac- turers warranty to Seller. The obligations under the foregoing warranties are limited to the precise terms thereof. These warranties provide exclusive remedies, expressly in lieu of all other remedies including claims for special or consequential damages. SELLER NEITHER MAKES NOR ASSUMES ANY OTHER WARRANTY WHATSOEVER, WHETHER EXPRESS, STATUTORY, OR IMPLIED, IN- CLUDING WARRANTIES OF MERCHANTABILITY AND FITNESS, AND NO PERSON IS AUTHORIZED TO ASSUME FOR SELLER ANY OBLIGA- TION OR LIABILITY NOT STRICTLY IN ACCORDANCE WITH THE FOREGOING.
