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1、TO nnnn-nn-nnn-nn Instruction Book with Parts List TERMALINE LOAD RESISTOR MODEL 8833-300 Bird Electronic Corporation nnnnnn-nn-n-nnnn January 1, 1996 Copyright 1996 by Bird Electronic Corporation Instruction Book Part Number TO-nnnn-nn-nnn-nn Termaline is a registered trademark of Bird Electronic C
2、orporation 30303 Aurora Road Cleveland (Solon), Ohio 44139-2794 RadioFans.CN 收音机爱 好者资料库 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 confor
3、m to applicable specifications, drawings, blueprints and/or samples. Sellers sole obligation under these warranties shall be to issue credit, repair or replace any item or part thereof which is proved to be other than as war- ranted; no allowance shall be made for any labor charges of Buyer for repl
4、acement of parts, adjust- ment or repairs, 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 speci- fications, drawings, blueprints and/or samples, Seller shall, upon prompt noti
5、ce 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, wil
6、l be borne by Seller and reimburse- ment 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
7、 extend to any prod- ucts or parts thereof which have been subjected to any misuse or neglect, damaged by accident, ren- dered 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 furnishe
8、d by Buyer or acquired from others at Buyers request and/or to Buyers specifi- cations. In addition, Sellers warranties do not extend to the failure of tubes, transistors, fuses and batter- ies, or to other equipment and parts manufactured by others except to the extent of the original manu- facture
9、rs 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 conse- quential damages. SELLER NEITHER MAKES NOR ASSUMES ANY OTHER WAR
10、RANTY WHATSO- EVER, WHETHER EXPRESS, STATUTORY, OR IMPLIED, INCLUDING WARRANTIES OF MER- CHANTABILITY AND FITNESS, AND NO PERSON IS AUTHORIZED TO ASSUME FOR SELLER ANY OBLIGATION OR LIABILITY NOT STRICTLY IN AC- CORDANCE WITH THE FOREGOING. RadioFans.CN 收音机爱 好者资料库 SAFETY PRECAUTIONS The following ar
11、e general safety precautions that are not necessarily related to any specific part or proce- dure and do not necessarily appear elsewhere in this publication. Keep Away From Live Circuits Operating personnel must at all times observe normal safety regulations. Do not attempt to replace parts or disc
12、onnect an RF transmission or any other high voltage line while power is applied. When working with high voltage always have someone present who is capable of rendering aid if necessary. Personnel working with or near high voltage should be familiar with modern methods of resuscitation. Warning Warni
13、ng notes call attention to a procedure, which if not correctly performed could result in personal in- jury. Caution Caution notes call attention to a procedure, which if not correctly performed could result in damage to the instrument. The following will appear in the text of this publication and ar
14、e shown here for emphasis. Warning Before placing the unit into operation, remove the shipping plug at the top of radiator, near front, sub- stitute with the specially shielded breather plug. Use a 3/4 inch flat wrench for this purpose - do not lose the O-Ring seal. This vent hole must remain open a
15、t all times when the unit is in operation or cooling. Failure to do this could result in damage to the equipment and endanger the operators safety. The use of the vent plug also protects the filler opening against intrusion of foreign material while allowing unobstructed venting of the tank. The shi
16、pping plug (with O-Ring seal) should be put back in place whenever the unit is to be transported. Be sure to check this plug. Warning Never attempt to disconnect RF equipment from a transmission line while RF power is being applied. Leaking RF energy is a potential health hazard. Warning Provide ade
17、quate ventilation and observe normal precautions when using dry cleaning solvents. Many dry cleaning agents emit toxic fumes that may be harmful to your health if inhaled. RF Load Resistor Model 8833-300 Page 3 RadioFans.CN 收音机爱 好者资料库 Table Of Contents 1. Introduction5 Purpose and Function5 Descript
18、ion5 RF Input5 Coolant5 Vent5 Items Supplied5 Specifications5 Component Location6 Installation7 Mounting7 Orientation7 Vent7 Installing Vent Plug7 Thermoswitch7 Checking the DC Resistance8 Theory of Operation9 General9 Dielectric Coolant9 Radiator9 Operating Instructions10 Load Resistor Connection10
19、 Load Resistor Operation10 Maintenance11 General11 Checking DC Resistance of the Load Resistor11 Removing the Load Resistor11 Installing the Load Resistor11 Preventing Coolant Leakage12 Checking Coolant Level12 Pressure Vent12 RF Input Connector12 TO-nnn-nn-nnn-nn Page 4 Introduction 1.1Purpose and
20、Function The Model 8833-300 Termaline Load Resistor is designed as a low reflection and nonradiating termi- nation for coaxial transmission lines. It is a useful aid in the tuning and troubleshooting of transmission equipment within its rating. 1.2Description The Model 8833-300 RF Load is fully self
21、-contained. No additional equipment or outside power source is required. Attached to the front and rear panels of the rhombic-shaped radiator are mounting flanges. These flanges act as supports for free standing use in portable applications, or as mounting brackets for optional fixed installation. T
22、here are mounting slots provided in the flanges for this purpose, see Section 2 - Installation. Convenient carrying tabs are also provided at each end of the radiator. 1.3RF Input The RF input connection is on the lower front face of the unit. The Model 8833-300 is designed for use with coaxial cabl
23、e using large LC or LT connectors. A female LC connector is installed at the factory, a female N connector is also supplied. Bird Quick- Change “QC” connectors, and how to change them, are described in Section 5 - Maintenance. 1.4Coolant The load unit is filled with a specially selected dielec- tric
24、 coolant chosen for its desirable thermal charac- teristics and dielectric properties. 1.5Vent The coolant inlet, when capped with the vent plug, relieves internal pressure resulting from expansion of heated coolant. 1.6Items Supplied Model 8833-300 RF Load Resistor Female LC Connector (installed) F
25、emale N Connector Shipping Plug with O-Ring Seal (installed) Vent Plug with O-Ring Seal (attached by chain) Coolant (installed) Interlock Thermoswitch (optional) 1.7Specifications Refer to Table-1 for operational specifications. Power Rating1000 W continuous duty RF Input Impedance50 ohm Input Conne
26、ctorBird “QC” type, female LC normally supplied installed. Female N supplied as an accessory. Frequency RangeDC - 2.5 GHz VSWR dc-1 GHz 1-2.5 GHz 1.10:1.0 1.25:1.0 Ambient Temperature-40C to +45C (-40F to +113F) Dimensions21-45/64L x 7-1/8W x 17-3/16H (551 x 181 x 437 mm) Weight54 lb 10 oz (24.8 kg)
27、 FinishLight navy gray (MIL-E-15090C) Cooling MethodLiquid dielectric and natural air convection Table - 1 Specifications RF Load Resistor Model 8833-300 Page 5 1.8Component Location Refer to the following Outline Drawing, Figure- 1, for dimensions and component location. 2. Installation 2.1Mounting
28、 The Model 8833-300 Load Resistor is equipped for either fixed installations or portable use. The load is Figure - 1 Outline Drawing TO-nnn-nn-nnn-nn Page 6 free standing or can be attached to a bench, etc., Refer to Figure-1, Outline Drawing, for location of the two mounting brackets and four mount
29、ing holes. Attach the load using four suitable fasteners. 2.2Orientation This equipment is designed for operation in an up- right position only, as shown in Figure-1, Outline Drawing. Do not attempt to operate in any other position. 2.3Vent The coolant filler inlet is capped with a shipping plug, Fi
30、gure-2, during transport from the factory. The ship- ping plug must be removed and replaced with the vent plug, Figure-3, before operation. The vent plug must also remain installed during cooling. 2.4Installing Vent Plug Warning Failure to properly vent the radiator during operation and cooling can
31、result in equipment damage and personal injury. Remove the shipping plug using a 3/4 flat wrench. Ensure the o-ring seal stays in place on the shipping plug. Ensure the o-ring seal is in place on the vent plug. Install vent plug. 2.5Thermoswitch A thermoswitch assembly, P/N 2450-056, is an avail- ab
32、le option. When installed in the radiator, it will prevent damage from accidental transmitter power overload or equipment malfunction. Being normally closed, the thermoswitch opens at a maximum safe temperature. Connected in series with the transmitter interlock, it cuts off transmitter power if loa
33、d tempera- ture exceeds this value. The assembly consists of the thermoswitch body, P/N 2450-040, with coupling jack, P/N 2450-018, attached. Thermoswitch Installation Place the unit on its back, with the connector end up. This position prevents coolant spillage. Use a 9/16 allen wrench to remove th
34、e socket plug on the front face of the radiator. Replace the plug with the thermoswitch. Use an acceptable pipe sealing compound sparingly, on the external threads only, of the thermoswitch. Do not contaminate coolant with pipe sealing compound. Observe closely for coolant leaks upon completion. Con
35、necting the Thermoswitch, see Figure-4 Unscrew the knurled ring-nut A at the lower end of the coupling jack assembly. Pull it off the ther- moswitch jack B. Unscrew the small knurled cover fitting C from the base plug D of the connector to release the base. Thread the interlock wires through the cla
36、mp E (with washers F inside) and with its threaded fitting in p l a Figure - 2 Shipping Plug Figure - 3 Vent Plug RF Load Resistor Model 8833-300 Page 7 Note: Be sure that the knurled ring nut A is in place over the base plug D with the knurled end outward (towards face). Screw on the cover ring C.
37、Fasten the cable clamp E, and tighten the two yoke screws H on the cable. Push the plug back on the thermoswitch, and tighten captive knurled connecting ring. Do not attempt to operate the equipment without interlock attached. 2.6Checking the DC Resistance VSWR and RF Impedance are the true benchmar
38、k of a quality dummy load. Checking the dc resistance is simply used to measure a change in the condition of the resistor over a period of time. If the application requires such measurements, follow the steps below to obtain a benchmark value before the unit is put into service. Preparation and Tool
39、s Required Be sure the vent plug is installed, see paragraph 2.4. Tools: Resistance Bridge or Ohmmeter with accuracy of 1% 50 ohms. Temperature of the load is 20 to 25C (68 to 70F). Procedure Using the resistance bridge or ohmmeter, check the dc resistance of the load before it is put into service,
40、see Figure-5. Record the value and keep for future use. 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 resis- tance. Check the resistance of the load periodically, accord- ing to use, and compare this
41、resistance with the original reading. If the values vary more than 2 ohms this could be an indication of a failing resistive ele- ment. 3.Theory of Operation 3.1General The Model 8833-300 RF Load consists of a film-on- ceramic resistor immersed in a dielectric coolant. The resistor, which is individ
42、ually selected for its accu- racy, is enclosed in an exponentially tapered housing, providing a reduction in surge impedance directly proportional to the distance along the resistor. When the resistor unit is immersed in the dielectric liquid, the characteristic impedance will be 50 ohms at the conn
43、ector end and graduate to zero ohms at the rear, where the resistor joins the housing forming the return conductor of the coaxial circuit. This produces a uniform, practically reflectionless, line termination over the stated frequencies of the load resistor. 3.2Dielectric Coolant The dielectric cool
44、ant, a low volatility, high flash point synthetic oil, is chosen for its desirable thermal char- acteristics and dielectric properties, to which the diameters of the resistor housing are matched. A synthetic rubber o-ring around the outside of the r e s Figure - 4 Thermoswitch Assembly Figure - 5 Ch
45、ecking DC Resistance TO-nnn-nn-nnn-nn Page 8 istor housing mount furnishes a seal for the radiator opening. A beveled flange retains the o-ring. The o-ring is pressed against the radiator face by the action of drawing up of radial V-band clamp around the enclosing beveled flanges. 3.3Radiator When i
46、nput power is applied, the resistor generates heat which is absorbed by the surrounding dielectric coolant. By convection, the heated oil flows through holes in the coaxial shell to the walls of the radiator tank. This radiator is a fabricated single-unit construc- tion, and is carefully designed of
47、 heat-sink sections on a unique vertical rhombic form. This provides a very high efficiency of heat transfer from the dielectric coolant into the surrounding air. 4.Operating Instructions 4.1Load Resistor Connection Warning Provide adequate ventilation and observe normal precautions when using dry c
48、leaning solvents. Many dry cleaning agents emit toxic fumes that may be harmful to your health if inhaled. Clean all conductors and insulator surfaces on the transmission line face and check the RF input con- nector. Use an aerosol type contact cleaner or any dry cleaning solvent on a cotton swab st
49、ick, if nec- essary. Attach the Model 8833-300 Load Resistor to the RF line with a 50 ohm coaxial cable such as RG-218/U or RG-220/U (-17A or 19A) with a suitable plug attached. Check that all coaxial power line connec- tions are properly tightened. Avoid the use of adapt- ers and elbows whenever possible. 4.2Load Resistor Operation Warning Never attempt to disconnect RF equipment from a transmission line while RF power is being applied. Leaking RF energy is a potential health hazard. Proceed according to the instructions pertaining to the specific transmitting equipment. There are
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