Product User Manual - Gerling Applied Engineering, Inc.
Contents
1. Product User Manual 4 Models GA1202 Short Dummy Load WR340 Document 930098 Rev 1 Gerling Applied Engineering Inc P O Box 580816 Modesto CA 95358 www 2450mhz com Product User Manual Page 2 Model GA1202 Short Dummy Load WR340 930098 Rev 1 REVISION HISTORY REV DESCRIPTION DATE APPROVAL 1 RELEASED 27MARO8 JFG WARRANTY Products manufactured and sold by Gerling Applied Engineering Inc GAE are warranted to be free of defects in materials and workmanship under normal use and service for a period of twelve 12 months from the date of original shipment GAE s obligation under this warranty is limited to repairing or replacing at GAE s option all non consumable component parts Consumable parts are specifically excluded from this warranty and may include but are not be limited to magnetrons fuses lamps seals o rings v belts and fluids All warranty repairs are to be done at GAE s facility or as otherwise authorized by GAE All shipping charges for warranty repair or replacement are the purchaser s responsibility unless otherwise agreed to by GAE This warranty supercedes all other warranties expressed or implied No warranty is given covering the product for any particular purpose other than as covered by the applicable product specifications GAE assumes no liability in any event for incidental or consequential damages financial losses pena2. To ensure safe operation and prevent microwave leakage the equipment must be periodically inspected and maintained as required or recommended 2008 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 4 Model GA1202 Short Dummy Load WR340 TABLE OF CONTENTS 930098 Rev 1 EQUIPMENT DESCRIPTION ccccccccccesssesssseeeeeeeeeeeeeeeeees Specifications Outline Drawing INSTALLATION cos aaa Preliminary Inspection Waveguide Configuration Flange Connections Water Flow Requirements Water Fitting Connections Storage and Shipping THEORY OF OPERATION cc cccticninin canizaninicininicaninisdcicicncida Basic Operation Performance Considerations USER MAINTENANCE AND REPAIR ceceeeeeeeeeeeeees Insert Block Replacement Procedure 2008 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 5 Model GA1202 Short Dummy Load WR340 930098 Rev 1 EQUIPMENT DESCRIPTION Specifications The GA1202 Short Dummy Load is designed for use in high power microwave networks as a means to dissipate up to 6kW of microwave power that is not being utilized for other purposes The compact design and high reliability of these loads make them ideal for a variety of uses Typical applications include magnetron isolation from reflected power when used with a 3 port circulator high power test stations and variable Q applicators Microwave power delivere
3. as adopted by OSHA the International Electrotechnical Commission IEC and other regulatory agencies limit leakage to 5 mW cm measured at 5 cm from the leakage source under normal operating conditions and 10 mW cm at 5 cm from the source under abnormal operating conditions The U S Federal Communications Commission FCC has established regulations limiting the emission of energy at frequencies outside the ISM bands All GAE waveguide components meets these requirements when properly connected to another waveguide component Water Flow Requirements A A source of water must be connected to the dummy load that provides an adequate rate of flow The nominal water flow rate is 1 0 gpm However the flow rate must be maintained such that the outlet water temperature does not exceed 150 F The minimum allowable flow rate depends on the level of incident microwave power and the inlet water temperature Figure 2 below shows the minimum flow rate vs incident microwave power and inlet water temperature MINIMUM WATER FLOW RATES for given input power levels a 6 kW a 5 kW E 4 kW 3 kW e 2 kW 1 kW Water Flow Rate gpm 1 0 10 15 20 25 30 35 40 45 Inlet Water Temp deg C Figure 2 Recommended minimum water flow rates for given inlet water temperature and
4. incident microwave power level CAUTION Failure to provide an adequate rate of water flow can result in severe damage to the dummy load It is strongly recommended that an interlock device such as an in line water flow 2008 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 9 Model GA1202 Short Dummy Load WR340 930098 Rev 1 switch be used to prevent operation of the microwave generator in the event of inadequate or loss of water flow Water Fitting Connections Standard 1 8 NPT female fittings are provided at the end of the dummy load opposite the waveguide flange The source of water can be connected to either fitting It is recommended that a thread sealant such as Teflon pipe thread tape be used to ensure a leak free connection Care should be taken to prevent debris from falling into the fitting holes Storage and Shipping Upon removing the dummy load from the set up it is recommended that all water be drained prior to storage or shipping This precaution will prevent damage in the event that freezing temperatures are encountered during storage or shipping 2008 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 10 Model GA1202 Short Dummy Load WR340 930098 Rev 1 THEORY OF OPERATION Basic Operation The GA1202 dummy load utilizes water as the medium for absorbing microwave energy that enters through the waveguide flange The internal UHMW p
5. ble damage to the packaging material or dummy load should be noted and reported immediately to the shipping company in accordance with standard claims procedures The following components are included a Short Dummy Load b Product User Manual Waveguide Configuration The dummy load can be connected to and used with any common waveguide component having a compatible flange The mounting position can be in any orientation Figure 1 below illustrates a common configuration in which the dummy load is used in conjunction with a 3 port circulator to protect the magnetron by absorbing microwave power reflected from the process load MICROWAVE GENERATOR DUMMY LOAD 3 APPLICATOR CIRCULATOR DIRECTIONAL COUPLER TUNER SHORT CIRCUIT TERMINATION Figure 1 Typical waveguide configuration using the dummy load to absorb reflected microwave power Flange Connections The waveguide flange of the dummy load must be properly connected to another waveguide component having a similar flange style Bolts and nuts must be installed at all flange bolt holes and tightened securely prior to operation 2008 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 8 Model GA1202 Short Dummy Load WR340 930098 Rev 1 O Microwave Leakage Regulatory limits for microwave leakage relate to standards for human safety and interference with other electronic devices Standards for human safety
6. d to the dummy load is absorbed by water which internally flows through channels in a solid UHMW polyethylene block Naval brass is used for all water fitting connections to minimize corrosion The waveguide body is fabricated with dip brazed aluminum Waveguide WR340 Flange UG 554 U Frequency 2450 MHz nominal Incident Power Up to 6kW continuous Return Loss 20 dB min 2450 MHz Water Connections 1 8 NPT female Water Flow 1 0 gpm nominal 2 0 gom maximum Water Pressure 70 psi maximum Water Temp Inlet 40 F 4 C minimum Outlet 150 F 66 C maximum 2008 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 6 Model GA1202 Short Dummy Load WR340 Outline Drawing gt 44 11 el 3 56 90 930098 Rev 1 10X 9 265 6 7 FLANGE BOLT HOLES WR340 FLANGE hj 4 75 121 _ 5 44 138 2X WATER CONNECTIONS 1 8 NPT FEMALE l O O g O O el 1 86 47 O O 3 75 95 O O 2X 9 250 6 4 O O O FLANGE ALIGNMENT HOLES gt A 1 2008 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 7 Model GA1202 Short Dummy Load WR340 930098 Rev 1 INSTALLATION Preliminary Inspection Upon arrival at the installation site the dummy load should be thoroughly inspected for damage or wear caused during shipping Any visi
7. e the dummy load from the waveguide set up and drain the water from inside the load Remove the button head screw from the waveguide side and remove the matching slug Remove the two socket head screws at the back of the dummy load Insert the hex driver into one of the two screw holes and gently push the insert block out of the dummy load waveguide Reassembly 1 3 1 Inspect the inside of the waveguide for signs of damage and or corrosion In particular carefully inspect the four o rings seats on the inside of the back wall Additional repairs may be required in the event of internal damage or excess corrosion CAUTION Excess corrosion can prevent a water tight seal or cause premature failure of the seals and result in damage to other equipment In this case the dummy load may not be repairable and should be discarded 2008 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 12 Model GA1202 Short Dummy Load WR340 930098 Rev 1 1 3 2 1 3 3 1 3 4 1 3 5 1 3 6 1 3 7 Remove the four greased o rings from the polyethylene bag and place them into each of the four seats on the inside back wall of the dummy load Carefully slide the insert block assembly into the dummy load waveguide Ensure that the two plugs with smaller o rings on the sides of the block are fully inserted into the counter bore holes CAUTION If the plugs have come out as may happen during shipping ease th
8. em back in while being careful to avoid nicking the o rings on the edge of the counter bore Insert the two 14 20 socket head screws into the counter bored holes at the end of the waveguide and engage the screw threads into the insert block Carefully tighten the screws with the hex driver just enough to compress the o rings CAUTION Over tightening the screws will cause the Helicoil inserts inside the block to become loose and may result in permanent damage to the insert block Reinstall the matching slug and secure with the 8 32 button head screw Install water fittings apply water pressure 70 psi max and check for water leaks Reinstall dummy load into waveguide set up SMALL O RING PLUG es INSERT BLOCK A S 48 32 BUTTON HEAD SCREW y LARGE O RING MATCHING SLUG DUMMY LOAD WAVEGUIDE 1 4 20 SOCKET HEAD SCREW ITEMS INCLUDED WITH GA8105 INSERT REPAIR KIT Figure 3 Exploded view of dummy load assembly 2008 Gerling Applied Engineering Inc Modesto CA
9. lties or other losses incurred in conjunction with the use of GAE products DOCUMENT CONVENTIONS NOTE Means the reader should take note Notes contain helpful information suggestions or references to other sections chapters or documents CAUTION Means the reader should be careful You are doing something that might result in equipment damage or loss of data WARNING Means danger A situation exists that could cause bodily injury or death All personnel must be aware of the hazards involved with high voltage electrical circuitry and high power microwave devices rr J 2008 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 3 Model GA1202 Short Dummy Load WR340 930098 Rev 1 WARNING All waveguide dummy loads manufactured by GAE are intended for use with other equipment capable of producing a microwave field that is potentially hazardous to operating personnel It must never be connected or operated in a manner that allows a field in excess of 10 milliwatts per square centimeter to be generated in an area accessible to operating personnel Contact GAE Inc for technical support prior to installation and or operation of this unit if there is any question or concern about microwave leakage All waveguide flange and electrical cable connections throughout the system must be secure prior to operation Never operate the microwave generator without a properly rated absorbing load attached
10. olyethylene block through which the water flows is transparent to microwave energy referred to as having low dielectric loss characteristics and allows the energy to be absorbed directly into the water The dielectric loss of water is relatively high and is capable of absorbing over 99 of the incident microwave energy Performance Considerations In order to absorb substantially all of the incident microwave energy the characteristic impedance of the dummy load must be a close match to that of the waveguide to which it is connected The factors that influence this impedance match include the microwave frequency the dielectric properties of the insert block and the water and the physical geometry of the block and the channels through which the water flows The dielectric properties of most materials vary with changes in temperature In the case of water an increase in temperature causes a decrease in its dielectric loss and in general results in a decrease in microwave energy absorption However the geometry of the absorbing load can be optimized or tuned for the dielectric properties at a desired temperature In this case energy absorption is maximized at the design temperature and is reduced at both higher and lower temperatures The dummy load is designed for optimal performance at inlet water temperatures between 75 F 24 C and 85 F 29 C For best performance the outlet water temperature should remain as cl
11. ose as possible to the inlet temperature A low water flow rate and high incident power causes a large increase in temperature which since the heated water is still inside the load results in a detuning of the load impedance and a decrease in energy absorption 2008 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 11 Model GA1202 Short Dummy Load WR340 930098 Rev 1 USER MAINTENANCE AND REPAIR The GA1202 dummy load is designed to be maintenance free and does not require any user maintenance under normal operating conditions However the dummy load can sustain damage if the water flow rate is insufficient to prevent vaporization boiling while operating under conditions of high incident microwave power In the event of damage due to insufficient or lack of water flow the dummy load can be easily repaired by replacing the polyethylene insert block Repair kit model GA8105 available from GAE includes all necessary components for replacement of the insert block Insert Block Replacement Procedure 1 1 1 2 1 3 Equipment Requirements Hex Allen drivers 3 32 3 16 Disassembly 1 2 1 1 2 2 1 2 3 1 2 4 1 2 5 WARNING Turn off microwave power and disconnect line power from the microwave generator before disconnecting any waveguide components Disconnect the water supply and drain from the water fitting connections at the back of the dummy load Remov
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