HP Thermometer 11941A User's Manual
Contents
1. E Mn Log Freg Sweep SWEEP MODE ue Saya ases 02 8 deles dod M a Bo DADA AA odk Cont STAR PEKN dandi act e M E er tick Ee ru Sen aa dain 100 kHz STOP e Pau awia DES DER e decens r d dove tes i Lee lin pP oet 30 MHz LU PRO A 15 dBm 3 Physically align the probes as shown in figures 13 and 14 The identification label of the DUT should face upward This alignment illuminates one of the sense loops of the DUT with a magnetic field SOURCE DUT WORK SURFACE PREFERABLY WOODEN Figure 13 Probe Orientation for Insertion Loss Test TOP VIEW OBE 9 KHz 30 MHz THH OF THX 3980 SOURCE Figure 14 Detail of Probe Orientation for Insertion Loss Test Measurement of Loop 1 HP 11941 OPERATION NOTE 4 Press the STORE DATA key then Stor 5 Realign the DUT as shown in f igure 15 The calibration label of the DUT should face upward This position illuminates the second sense loop of the DUT with the same magnetic field intensity as the first loop eg 6 Press the STORE DATA key and Store Reg 07 Then press the INPUT key and Data The two displayed traces will typically be 3 dB apart for properly functioning probes and 6 dB apart for damaged probes If your measurements are repeatedly yielding results between 3 dB and 6 dB then the test setup should be checked TOP VIEW BE 9 KHz 30 KHz SOURCE E Figure 15 Detail of Probe2. E Ch 65 3 39 51 5 155 8 dBuV m 61 7 V m S mW 65 3 39 1043 0 dp MY mW 3 9 Localized Field Source 3 10 The probe can also be used as a localized magnetic field source for locating susceptible components on a circuit board It is a reciprocal device that is a current fed into the probe will generate a magnetic field at the dual loop sensor The specified antenna factors cannot be used to estimate the magnitude of the output field Table 2 lists characteristic field strengths developed 1 mm 0 040 in away from the probe tip using an incident power of 0 dBm into 50 ohms Power applied to the probe must not exceed the maximum input power listed in table 1 or damage to the probe will result HP 11941 OPERATION NOTE DUAL LOOPS Figure 2 Magnetic Field Orientation for Maximum Coupling Table 2 Characteristic Magnetic Field Strengths 3 11 Test Setups 3 12 The HP 11941A operates as either a localized magnetic field probe or localized magnetic field source The following paragraphs describe different applications and test setups for the probe Table 3 lists the recommended test setup equipment used in these examples Any equipment that satisfies the critical specifications listed in table 3 may be substituted for the recommended equipment When used as a probe be sure to add the antenna factors and cable losses to the signal levels indicated on the spectrum analyzer If a preamplifier is used to
3. Figure 6 Probe Tip Detail HP 11941 OPERATION NOTE HP Figure 7 Testing an Enclosure Seam ANTENNA FACTOR LABEL COVER SENSOR P C BOARD Figure 8 Testing Coaxial Cable HP 11941 OPERATION NOTE OV C OT 4 1 OPERATION VERIFICATION 4 2 Operation Verification for the HP 11941A consists of two tests an output impedance measurement test and an insertion loss measurement test Each test is relative and designed to detect damage in specific parts of the circuitry These tests are not designed to verify antenna factor calibration which requires a calibrated magnetic field 4 3 Probes that fail these tests may still detect electromagnetic radiation In this case the probe circuitry no longer rejects electric field coupling and the antenna factors listed on the unit are no longer valid 4 4 In the test procedures instrument softkeys will be represented by shadow print Softkeys are keys whose function is defined by text on the display 4 5 Calibration Cycle 4 6 Field site recalibration of the HP 11941A antenna factors is not possible However the probe s antenna factors can be recalibrated at the factory A three 3 year recertification cycle is recommended Refer to section 6 1 for factory recalibration information 4 7 The HP 11941A contains no internal user accessible adjustments or parts The SMA adapter see figure 16 is the only external replaceable part 4 8 Output Impedance Measureme
4. or software or firmware will be uninterrupted or error free LIMITATION OF WARRANTY The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by Buyer Buyer supplied software or interfacing unauthorized modification or misuse operation outside of the environmental specifications for the product or improper site preparation or maintenance NO OTHER WARRANTY IS EXPRESSED OR IMPLIED HP SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE SE T EXCLUSIVE REMEDIES THE REMEDIES PROVIDED HEREIN ARE BUYERS SOLE AND EXCLUSIVE REMEDIES HP SHALL NOT BE LIABLE FOR ANY DIRECT INDIRECT SPECIAL INCIDENTAL OR CONSE QUENTIAL DAMAGES WHETHER BASED ON CONTRACT TORT OR ANY OTHER LEGAL THEORY ASSISTANCE Product maintenance agreements and other customer assistance agreements are available for Hewlerr Packard products For any assistance contact vour nearest Hewlett Packard Sales and Service Office Addresses are provid ed at the back of this manual 1 1 Gener l Information oe ee ORC ESS 1 1 2 Description P 1 1 4 Accessories I l 6 Options 5535 6 I AA 1 1 11 Initial Inspection ert no 1 2 1 Specifications ECC Roe RN 2 3 1 Operation
5. POLAR SMITH CHART Dr T cup TRUE P ON FULL SCALE oa ee GI 1 UNIT SWEEP TYPE puyuy u am A R S a Lin Freg Sweep SWEEP MODE LT pP Cont START FREQ a ROBIA UK AS A d S 100 kHz STOPFREQ E E EES OOP 1 MHz 3 Perform the full one port calibration by pressing the Measr Cal key and the directions on the display 4 Connect the probe to Port One of the HP 35677A The impedance display should appear as shown in figure 10 At 100 kHz the measured impedance should approximate that of a short circuit at 1 MHz the probe should measure inductively with a maximum normalized impedance value of 30 50 The most common failure mode for this test would be an open in the input circuitry in which case the impedance display would appear as shown in figure 11 li je PSY HP 11941 OPERATION NOTE 4 9 Insertion Loss Measurement Test Description The insertion loss test is a relative indicator of damage in the input circuitry Using a second HP 119414 as a magnetic field source this test selectively injects a magnetic field into each loop of the HP 11941A being tested Damage is indicated by differences in the measured output voltages It is important to orient the two probes properly as shown in figures 12 through 15 To facilitate testing the source probe should be fixed in place the tip flush with the work surface preferably
6. wooden This can be accomplished with clamps or tape which should be no closer than 50 8 mm 2 in to the source tip Other test equipment may be substituted if it meets or exceeds the critical specifications for the instruments listed below Throughout the test procedure the probe being tested will be referred to as the DUT Device Under Test Recommended Equipment Network Analyzer wh TEL P LI a 3577 S Parameter Test POP AE oats HP 35677A Field Source 4 HP 11941A Adapters Type m to 35 m Q required HP 1250 1743 Cables SMA m to SMA m 2m 2 required HP 8120 4811 Procedure 1 Connect the equipment as shown in figure 12 Allow the HP 3577A 60 minutes of warm up time HP 3577A NETWORK ANALYZER s ng emm dd mawan 356774 S PARAMETER TEST SET SMA CABLE ASSY SOURCE DUT SEE DETAIL IN FIGURE 14 Figure 12 Insertion Loss Test Setup HP 11941 OPERATION NOTE EET Ej OE OE 2 Set the HP 3577A as follows INST PRESET TRACE I INPUT ls cea ona x 521 DISPLAY FUNCTION den Log Mag REF LEVEL ooa RADA euni O Leer 30 dBm 5 dB Div EE yy aya M 100 SWEEP TYPE 455538
7. 5 10 41 Maximum voltage at tip 1 kV de peak ac D ed L i Seng wema E Shipping 0 56 kg 1 2 lbs DIMENSIONS MILLIMETERS AND INCHES supplemental characteristic 6dB MOM 2dB r OCTAVE AAA so 80 ANTENNA FACTOR d r e 0 50 40 30 03 1 6 3 10 30 SSLOPE e DATA FREQUENCY MHz Figure 1 HP 119414 Characteristic Antenna Factors 9 kHz 30 MHz HP 11941 OPERATION NOTE T nr 3 6 Use the data included in figure 1 for interpolating antenna factors between the five calibration freguencies included in the probe s calibration table 3 7 Power Density and Electric Field Calculations 3 8 The HP 11941A measures magnetic field strength An estimate of the magnitude of the associated electric field can be made if a field impedance is assumed An example is given below using a 377 ohm field impedance Radiated power density can also be estimated assuming that the fields are in phase and that the field impedance is 377 ohms E Field Strength Va AF K 20 log 377 Ve AF K 51 5 Power Density dB YW Vaa AF K 104 3 cm where Vsa voltage dBu V measured on analyzer AF HP 11941A Antenna Factor in dB Alm K loss or gain in dB between HP 11941A and spectrum analyzer Positive value if loss negative value if gain EXAMPLE e At 10 MHz measured Vsa 65 3 dBuV Let K 0 and AF 39 an BAV then V i i
8. Hz 9 2 30 MHz Option H64 RF Gain HP 8447F 9 kHz 1 3 GHz gt 20 dB Option H64 An HP 85685 A RF Preselector may be substituted if an HP 8566B HP 8567A or HP 8568B spectrum analyzer is used HP 11941 OPERATION NOTE 3 14 Stimulus Response Test Setup The relative shielding effectiveness of various enclosures and shielded structures can be tested using stimulus response techniques See figure 4 The tracking generator output signal radiates from an antenna placed inside the enclosure under test while the probe and spectrum analyzer provide frequency and relative amplitude information See section 3 16 for proper probe placement MODULAR SPECTRUM ANALYZER ENCLOSURE UNDER TEST SOURCE ANTENNA AMPLIFIER RECOMMENDED TRACKING GENERATOR RF OUTPUT Figure 4 Stimulus Response Test Setup 3 15 Localized Susceptibility Test Setup Used as a field source the probe provides a magnetic field for susceptibility testing of electronic devices The distance between the probe tip and the Device Under Test DUT shouid be less than 1 cm 0 394 in As the probe is moved closer to the DUT the absolute magnetic field strength applied to the DUT approaches the calculated value produced at the probe tip For broadband susceptibility testing use the probe with a or tracking source See figure 5 for an example of the basic localized susceptibility test setup CAUTION Power applied to the probe m
9. OPERATION NOTE 11941A CLOSE FIELD PROBE HEWLETT PACKARD July 1987 A Copyright Hewlett Packard Company 1212 Valley House Drive Rohnert Park CA 949284999 U S A CERTIFICATION Hewlett Packard Company certifies that this product met its published specifications at the time of ship ment from the factory Hewlett Packard further certifies that its calibration measurements are traceable to the United States National Bureau of Standards to the extent allowed by the Bureau calibration facili tv and to the calibration facilities of the other International Standards Organization members WARRANTY This Hewlett Packard instrument product is warranted against defects in material and workmanship for period of one year from date of shipment During the warranty period Hewlett Packard Company will at its option either repair or replace products which prove to be defective For warranty service or repair this product must be returned to a service facility designated by HP Buyer shall prepay shipping charges to HP and HP shall pay shipping charges to return the product to Buyer However Buyer shall pay all shipping charges duties and taxes for products returned to HP from another country HP warrants that its software and firmware designated by HP for use with an instrument will execute its programming instructions when properly installed on that instrument HP does not warrant that the opera tion of the instrument
10. Orientation for Insertion Loss Test Measurement of Loop 2 5 1 REPLACEABLE PARTS 5 2 The SMA adapter located at the end of the probe is the only replaceable part on the HP 11941A see figure 16 It protects the probe s integral connector from mechanical damage and should be left on Should the end of the adapter become worn or damaged through use it can be replaced using the procedure outlined in paragraph 5 3 SMA AA DEBEN e are EE HP Part Number 1250 1158 Check Digit 3 Loctite 222033 O o o a RR a za PA rA HP Part Number 0470 0573 Check Digit 9 15 HP 11941 OPERATION NOTE 5 3 SMA Adapter Replacement Procedure SMA CONNECTOR SMA ADAPTER Figure 16 SMA Adapter Location 1 Use a 7 32 inch wrench to remove the old SMA adapter see 16 Turn the adapter counterclockwise as viewed f rom the rear end of the probe 2 Place a small amount of Loctite 2229 on two or three end threads of the new SMA adapter 3 Screw the new adapter clockwise into the probe s SMA connector 4 Using a torque wrench tighten the adapter to 24 inch pounds 5 4 SMA Rotary Joint Installation Procedure Option 001 ROTATING ROTARY CONNECTOR JOINT FIXED CONNECTOR Figure 17 RF Rotary Joint Mounted on Probe Option 001 1 Use a 7 32 inch wrench to remove the old SMA adapter see figure 16 Turn the adapter counterclockwise as viewed from the rear end of the probe 2 The SMA Rotary Joint has an SMA conn
11. Packard Schweiz AG 29 Chemin Chateau Bloc CH 1219 LeLignon Geneva IN ALL OTHER LOCATIONS Hewlett Packard Inter Americas 3200 Hillview Avenue Palo Aito California 94304 LA packano HP MANUAL PART NUMBER 11941 90001 PRINTED U S A
12. e to SMA female adapter HP Part Number 1250 1700 The double shielded cable RG 223 reduces measurement errors in high field impedance environments by minimizing current leakage through the braided coaxial outer conductors For less demanding applications the use of a more flexible single shielded cable type is sufficient e g RG 58 RG 174 1 6 Options 1 7 Three options are available for the HP 11941A 1 8 Option 001 includes a factory installed SMA RF Rotary Joint connector HP Part Number 0955 0323 Check Digit 5 See figure 17 The connector increases handling flexibility of the probe by removing any rotational torque from the interconnect cable The rotary joint is especially useful when making measurements using the double shielded cable Section 5 4 includes instructions on installing the rotary joint 1 9 Option 003 consists of the HP 11941A Close Field Probe without the double shielded cable or the two adapters 1 10 Option 910 includes an additional Operation Note 1 11 Initial inspection 1 12 If the shipment contents are incomplete or damaged notify the nearest Hewlett Packard office If the shipping container is damaged or the cushioning material shows signs of stress notify the carrier as well as the Hewlett Packard office Keep the shipping materials for the carrier s inspection The HP office will arrange for repair or replacement without waiting for a claim settlement 1 13 See Paragraph 4 1 for Operati
13. e ee ee 4 a I S ee 2 3 2 Theory of Operation were ks u T 2 3 4 Antenna Factors unik A TT 2 3 Power Density and Electric Field Calculations 4 3 9 Localized Field Gua EE ES 4 A 3 1 L Test Setups ARE BREA 4a ER 5 3 16 Measurement Techniques O 8 4 1 Operation Verification ENEE 10 4 5 Calibration Cycle ae a 10 4 8 Output Impedance Measurement a aaa PEU NER PU 10 4 9 Insertion Loss Measurement Test 13 5 1 Replaceable Parts ee uo A 15 5 3 SMA Adapter Replacement Procedure 16 5 4 SMA Rotary Joint Installation Procedur Option 001 16 5 5 Ordering Information e n n nn RR 17 5 7 Direct Mail Order System 17 6 1 Factory Returns lt 17 SAFETY SYMBOLS The following safety symbols are used throughout this manual and in the instrument Familiarize yourself with each of the symbols and its meaning before operating this instrument CAUTION js gt Instruction manual symbol The instrument will be marked with this symbol when it is necessary for the user to refer to the instruction manual in order to protect the instrument against damage Location of pertinent information within the manual is indicated by use of this symbol in the table of contents Indicates dan
14. ector located at each end One connector rotates with respect to the body of the rotary joint The other connector is fixed to the body Cover two or three end threads of the rotating end connector with a small amount of Loctite 2228 OVO HP 11941 OPERATION NOTE 3 Screw the rotating end of the rotary joint clockwise into the probe s SMA connector see figure 17 4 Using a 9 32 inch torque wrench tighten the rotary joint to 24 inch pounds 5 When attaching a cable to the rotary joint hold the rotary joint by hand to keep the connector from turning 5 5 Ordering Information 5 6 To order a part quote the Hewlett Packard part number with check digit indicate the quantity required and address the order to the nearest Hewlett Packard office The check digit will ensure accurate and timely processing of your order 5 7 Direct Mail Order System 5 8 Within the US A Hewlett Packard can supply parts through a direct mail order system Advantages of using the system are as follows a Direct ordering and shipment from the HP Parts Center in Mountain View California b No minimum or maximum purchase requirement on any mail order There is a minimum order amount for parts ordered through a local HP office when the orders require billing and invoicing c Prepaid transportation There is a small handling charge for each order d No invoices To provide these advan
15. ge before using and do not use the probe if the protective tip cover is missing or damaged 3 4 Antenna Factors _ 3 5 The specific antenna factors of each HP 11941A are measured to within 2 dB at five f reguencies 9 kHz 100 kHz 1 MHz 10 MHz and 30 MHz This calibration information is listed on the bottom cover of each probe The antenna factors are given in the units of dB LA m MV To calculate the magnetic field strength in dB LA m at a specific frequency add the amplitude of the measured voltage in dB uV as indicated on the spectrum analyzer to the antenna factor for that specific frequency To compensate for cable losses and preamplifier gains add the losses and subtract the gains in dB Refer to the following eguation gt hodili ee ON H Field Strength Vsa AF K where VsA voltage in dBu V measured on analyzer AF HP 11941A Antenna Factor in dB And K loss or gain in dB between HP 11941A and spectrum analyzer Positive value if loss negative value if gain HP 11941 OPERATION NOTE Table 1 HP 119414 Specifications Antenna Factor Measured for each unit at 0 009 0 100 1 10 and 30 MHz to within 2 dB in a 377 ohm field impedance See Figure 1 for characteristic antenna factor data Temperature Range 0 C to 40 C x1 dB Operating 10 to 65 C Storage 4 D Freguency Range 9 kHz 30 MHz Maximum Input Power 0 5 watts 264
16. gerous voltages are present Be extremely careful The CAUTION sign denotes a hazard It calls attention to a procedure which if not correctly performed or adhered to could result in damage to or destruction of the instrument Do not proceed beyond a CAUTION sign until the indicated conditions are fully understood and met The WARNING sign denotes a hazard It calls attention to a procedure which if not correctly performed or adhered to could result in injury or loss of life Do not proceed beyond a WARNING sign until the indicated conditions are fully understood and met n i HP 11941 OPERATION NOTE 1 1 GENERAL INFORMATION 1 2 Description 1 3 The HP 11941A Close Field Probe is a hand held electromagnetic field sensor designed to make repeatable calibrated magnetic field measurements from 9 kHz to 30 MHz It is optimized for the location and measurement of sources of electromagnetic interference EMI in electronic equipment The HP 11941A can also be used as a localized magnetic field source when operated in conjunction with an appropriate signal generator thereby allowing circuit board level susceptibility testing of instruments 1 4 Accessories Supplied 1 5 The following three accessories are included with the probe One 2m 66 ft double shielded RF cable with two SMA male end connectors HP Part Number 8120 4811 e male to SMA female adapter HP Part Number 1250 1250 One BNC mal
17. increase measurement sensitivity subtract its gain from the displayed signal level The dielectric material on the tip of the probe has a characteristic breakdown voltage of 1 kV To prevent damage to the probe and or personal injury to the user the probe should not be used where a potential of over 1 kV is available HP 11941 OPERATION NOTE 3 13 Localized Emissions Test Setup figure 3 illustrates a typical configuration used for localizing EMI emissions See section 3 16 for proper probe placement HP 8590A SPECTRUM ANALYZER DEVICE UNDER TEST AMPLIFIER HP 119414 RECOMMENDED Figure 3 Localized Emissions Test Setup Table 3 Recommended Test Setup Equipment Critical Specifications Recommended Model HP 8562A 100 Hz 2 9 GHz HP 8566B 100 Hz 300 GHz HP 8567A 10 kHz 1 5 GHz HP 8568B 100 Hz 1 5 GHz HP 8590A 10 kHz 1 5 GHz Option H51 Close Field EMC Feature Set HP 71100A 100 Hz 2 9 GHz Option 002 Frequency Range 9 kHz 30 MHz Spectrum Analyzer Frequency Range 9 kHz 30 MHz Tracking Generator HP 8444A 0 5 1500 MHz Option 059 For use with HP 8566B HP 8567A and HP 8568B HP 70300A 100 Hz 2 9 GHz For use with HP 71100A 2 EX Signal Generator Frequency Range 9 kHz 30 MHz HP 8660C 10 kHz 2 6 GHz HP 8662A 10 kHz 1280 MHz Preamplifier Frequency Range HP 8447A 9 kHz 50 M
18. nt Test Description This test measures the impedance of the HP 11941A at the SMA port over a frequency range of 100 kHz to 1 MHz to detect any damage in the output circuitry Any equipment that satisfies the following critical specifications for the test setup may be substituted for the recommended equipment Frequency Range RI EE 2 100 kHz to 1 MHz Fest Port Matei l os s peace x SER RO AGAR ubi Y v rend denos ut gt 15 dB Return Loss Recommended Equipment Network Analyzer esi pA Nae A dci d a HP 3577A S Parameter Test HP 35677A Adapters Type N m to APC 35 m a d RC POE HP 1250 1743 Accessories 50 ohm Load 35 4 HP 909D Option 011 Coaxial Short APC 3 5 D HP 1250 1769 Open EES HP 1250 1767 10 HP 11941 OPERATION NOTE E Procedure 1 Connect the eguipme t as shown in figure 9 Allow the HP 3577A 60 minutes of warm up time HP 3577 NETWORK ANALYZER Kapen mah ah k HP 35677A S PARAMETER TEST SET 1 ADAPTER l PROBE 0377 0 p CC Te e T DUT OPEN SHORT REF LOAD lt Figure 9 Output Impedance Test Setup 2 Set the HP 3577A controls as follows TRACE I INPUT EK SPO v S DD Sil DISPLAY FUNCTION Saa nn ee
19. on Verification HP 11941 OPERATION NOTE M M M M M M M M 2 1 SPECIFICATIONS 2 2 Specifications for the HP 11941A are listed in table An asterisk placed after an entry indicates a supplemental characteristic Supplemental characteristics are not specifications but are characteristics included as additional information for the user 2 3 Figure 1 illustrates the characteristic frequency response for the HP 11941A Close Field Probe See section 3 4 Antenna Factors for additional information 3 1 OPERATION 3 2 Theory of Operation 3 3 The HP 11941A is a balanced magnetic field sensor that provides an output voltage proportional to the strength of the magnetic field at its tip Radiated magnetic fields couple directly to the HP 11941A and produce an output signal radiated electric fields also couple to the HP 11941A but do not produce an output voltage due to the construction of the probe The HP 11941A uses a dual loop sensor and a balun to reject electrically coupled signals These loops are illustrated in figure 2 which shows the probe with its non removable protective tip cover cut away for clarity The probe does not rectify the input signal it provides both amplitude and frequency information It is ideally suited for use with a spectrum analyzer The HP 11941A circuitry is passive and therefore only contributes thermal noise to any measurement system Inspect the probe tip for dama
20. tages a check or money order must accompany each order Mail order forms and specific ordering information are available through your local HP office 6 1 FACTORY RETURNS 6 2 The 11941A probe may be returned to the factory for recalibration The probe should be properly packaged and shipped to HEWLETT PACKARD COMPANY ATTN WARRANTY ADMINISTRATOR 11941 REPAIR 1212 VALLEY HOUSE DRIVE ROHNERT PARK CA 94928 4999 USA HP 11941 OPERATION NOTE EE v HEWLETT PACKARD SALES AND SERVICE OFFICES To obtain servicing information or to order replacement parts contact the nearest Hewlett Packard Sales and Service Office listed in the HP Catalog or contact the nearest regional office listed below IN THE UNITED STATES CALIFORNIA P O Box 4230 1421 South Manhattan Avenue Fullerton 92631 GEORGIA PO Box 105005 2000 South Park Place Atlanta 30339 ILLINOIS 5201 Tollview Drive Rolling Meadows 60008 NEW JERSEY W 120 Century Road Paramus 07652 IN CANADA Hewlett Packard Canada Ltd 17500 South Service Road Trans Canada Highway Kirkland Quebec H9J 2M5 IN FRANCE Hewlett Packard France F 91947 Les Ulis Cedex Orsay IN GERMAN FEDERAL REPUBLIC Hewlett Packard GmbH Vertriebszentrale Frankfurt Berner Strasse 117 Postfach 560 140 D 6000 Frankfurt 56 L IN GREAT BRITAIN Hewlett Packard Ltd King Street Lane Winnersh Wokingham Berkshire RG11 SAR IN OTHER EUROPEAN COUNTRIES SWITZERLAND Hewlett
21. ust not exceed the maximum input power listed in table 1 or damage to the preve will result SIGNAL GENERATOR DEVICE UNDER TEST P C COMPONENT HP 119414 RF OUTPUT P C BOARD Figure 5 Localized Susceptibility Test Setup HP 11941 OPERATION NOTE r 3 16 Measurement Techniques 3 17 The HP 11941A measures the magnetic field strength at the center of its sense loop not at the probe tip Figure 6 details the relationship between the probe tip cover and the probe loop centerline The probe is designed to be held very close to potential radiating points The plane of the probe tip loops must be perpendicular to the radiating magnetic field as illustrated in f igure 2 For example if the seam of an enclosure is being tested for EMI hold the probe as illustrated in f igure 7 When measuring the radiation from a coaxial cable position the probe as in f igure 8 which shows the sense loops The side of the probe with the antenna factor calibration label should be f acing away from the cable being measured Do not use the probe if the protective tip cover is missing or damaged 3 18 The probe may be used as a source in susceptibility testing as described in section 3 9 and also in paragraph 3 15 In this application hold the probe within cm 0 394 in of the electronic circuit component being tested PROBE TIP COVER LOOP CENTERLINE I B MM 0 07 IN PROBE BOARD
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