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SCANEM-QC

ELECTROMAGNETIC NEAR-FIELD PROBE!

A computer has four major areas to look at for excessive radiation: (1) cables
attached to input/output connectors; (2) openings in the case for switches,
speed readouts, etc., (3) case joints where the two halves of the chassis may
not fit properly, and (4) the AC power cord. You will be looking for units that
produce a probe response of at least four or five LEDs being lit.

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Содержание ScanEM-QC CTK019

Страница 1: ...3M ScanEM QC Electromagnetic Near Field Probe Kit Model CTK019 User s Guide ...

Страница 2: ...ectrum analyzer 12 Non contact oscilloscope probes 12 Broadband field strength probe for a multimeter 14 Examples of applications of ScanEM QC probes 15 Analyzing the results 21 Troubleshooting 23 Common places to look for excessive emissions 23 During the design phase 24 Checking the prototype 24 Before the EMC test 24 Should things go wrong 24 Seeking help 24 EMC101 25 Why EMC 25 Near field prim...

Страница 3: ... Kit model CTK015 please visit www 3m com static Scan EM QC Contents The ScanEM QC Kit model CTK019 consists of One ScanEM EQC probe electric field model CTM034 One ScanEM HQC probe magnetic field model CTM036 One six foot 1 8 m SMB to BNC cable model AWD001 AAA batteries two per probe already installed Plastic storage box model CTA119 User s Guide Optional ScanEM QC Kit accesories Accessories Pac...

Страница 4: ...mer on ESD Audit using electromagnetic field tools please see page 27 of this User s Guide The ScanEM QC Kit offers a universal solution to electromagnetic compliance problems By themselves the ScanEM QC Probes are completely self contained EM field detectors When connected to test equipment the ScanEM QC Probes become broadband amplified near field probes In stand alone mode the ScanEM QC Probes ...

Страница 5: ...mission regulations Predict radiated EMC test results Pre test your product prior to an official compliance test in order to identify potential problems early Quickly troubleshoot a product that has failed a compliance test Find EM leakage on enclosures cables and connectors Find sources of EM interference Show the presence of a high frequency signal on a cable or wire without contact Observe ESD ...

Страница 6: ...ckground level It also works as a squelch control The stronger the emission level the higher the pitch of the sound Five LEDs indicate relative field strength The LEDs can be used with or without sound SMB male connector Connects ScanEM QC Probe to a spectrum analyzer oscilloscope frequency counter multimeter and other instruments 0 1 2 Level Sound On Press to Operate Output EM Level ScanEM HQC Co...

Страница 7: ... results may be meaningless and normal operation of the measured device may be influenced by parasitic capacitance introduced by the ScanEM EQC Probe in direct contact The ScanEM EQC Probe itself may be damaged as well if it is directly exposed to high voltage The 3M ScanEM HQC Probe however is designed to be put in direct contact with the insulation of the cable For the best results position the ...

Страница 8: ...h your thumb and hold it down Point the ScanEM QC Probe s antenna away from the tested product With your index finger adjust the Level dial so only the green LED is On Position the ScanEM QC Probe perpendicular to the tested area and bring its antenna as close as possible without actually touching the tested product With ScanEM HQC Probe set the cable into the groove of its antenna Move the ScanEM...

Страница 9: ... Level dial to the new background level You can use the Level dial to put the 3M ScanEM QC Probe in squelch mode Follow the procedure outlined in the previous paragraph only set the reference level just below the point where the green LED turns on This way your ScanEM QC Probe will be quiet and the lights will be off until you pass it over an area where the EM level is higher than your reference s...

Страница 10: ... can detect much finer variations in EM field strength than by using lights as the only indicator You may prefer to have the sound turned off to cut down on noise but this limits your resolution to just five steps five LEDs EM Level LED Bar The EM level LED bar is for relative estimates only and shouldn t be used for precise measurements The ScanEM QC Probe s LEDs are spaced on a somewhat linear s...

Страница 11: ...M QC Probe to a 50 Ohms input of a spectrum analyzer limits the DC signal to a maximum of 2 5mV without affecting the AC performance Always Set the Level Dial to zero When Using the ScanEM QC as a Probe Î Î When the Level dial is set to zero it disables the ScanEM QC Probe s own indication the LEDs and the speaker preventing any influence on the output signal Do not load the ScanEM QC Probe s outp...

Страница 12: ...inating the need for an external pre amplifier Figure C shows a typical frequency response of the 3M ScanEM EQC Probe vs an equivalent passive probe As seen passive probes typically fail at lower frequencies below 200MHz where most of the fundamental frequencies and many of the strongest harmonics of the tested equipment are located Avoid overloading the probes with a very strong field it may indu...

Страница 13: ...erefore it offers no loading whatsoever on the circuit under test Another problem inherent with scope probes is their bandwidth Probes typically have 60 100 or 250MHz bandwidth Cost for higher frequency probes is prohibitively high With today s high speed circuits low bandwidth tools may easily miss nanosecond long transients leaving engineers to wonder why their circuits behave the way they do Th...

Страница 14: ...h frequency currents on a signal or power trace without cutting the trace or spending hundreds or thousands of dollars on a special current probe that only works at much lower frequencies The ScanEM QC Probe as any field probe would shows the signal slightly differently than the one actually residing on the trace This is due to an antenna factor of the trace Experimenting with the ScanEM QC Probe ...

Страница 15: ...be with your hand it may induce a feedback between typically non shielded circuitry in a multimeter and the ScanEM QC Probe antenna that just got many times bigger by virtue of your touching it A typical transfer function of 3M ScanEM EQC Probe is shown in the figure to the left This figure is given for reference only All specifications are subject to change without notice Know What You are Measur...

Страница 16: ...hose agents use these probes to spot check for emission violators in the field The sensitivity and other parameters of the ScanEM QC Probes performance were set by the FCC Engineers to provide the best correlation with the far field test The following is a procedure on how to use the ScanEM QC Probe for checking a computer for compliance as recommended by the FCC Test of other products should be p...

Страница 17: ...jor areas to look at for excessive radiation 1 cables attached to input output connectors 2 openings in the case for switches speed readouts etc 3 case joints where the two halves of the chassis may not fit properly and 4 the AC power cord You will be looking for units that produce a probe response of at least four or five LEDs being lit ...

Страница 18: ...he change in audio pitch move the probe along the cable to locate the point where the probe response is highest The angle of orientation of the rod antenna relative to the cable should be varied to produce the maximum also The cable should not be handled at the time it is being investigated Recheck the probe Level setting 3 Chassis seams and openings in the chassis are investigated similarly by mo...

Страница 19: ...y concern that extraneous RF fields are affecting the probe the computer system should be relocated to a different building and the calibration process repeated 2 Place the computer AC power cord longitudinally in the center of the ferrite core as tightly as possible Move the probe up and down the length of the power cord If a high energy level is detected check the gain of the probe and remeasure...

Страница 20: ...l limits to emission based on known good product Other Applications Measuring Efficiency of Shielding Measure the field strength before and after the shield is applied to know the actual effectiveness of shielding Measuring the field strength on both sides of the shield also helps to evaluate shielding The 3M ScanEM EQC Probe and a multimeter can be used to check the quality of applied shielding a...

Страница 21: ... undershoot overshoot of pulses However you should be able to reliably detect the signal estimate its waveform measure the frequency of the signal for example all without influencing the signal This is especially important where direct contact with the circuit disrupts its normal operation or is dangerous Locating Bad Connections The ScanEM Probe can help in locating bad connections and broken tra...

Страница 22: ...icate excessive EM field strength in places where high frequency signals are not normally expected i e AC power lines This happens because high frequency signals produced elsewhere ride on these lines and generate an electromagnetic field Many low frequency signals contain a sufficient amount of high frequency harmonics for the ScanEM QC Probe to detect If any of these non sinewave signals are gen...

Страница 23: ...g seam in the shield If the offending frequency is well known and if the field carrying it is not the strongest one in the product a spectrum analyzer may be a more appropriate tool If the 3M ScanEM QC Electromagnetic Near Field Probe is used in the early stages of development where it is not yet clear what frequency will be of a concern the self contained mode will prove to be quick and effective...

Страница 24: ... trouble spots Any gaps or openings in the enclosure vents areas near buttons jacks or displays cables going through such openings All cable connectors and all cords normally connected to the product In general at frequencies below 200 300 MHz undesirable emission is produced by cables connected to or extended from the product At higher frequencies the sources typically lie inside the product Ofte...

Страница 25: ...r company thousands of dollars in a corrective redesign later Checking the Prototype Scan the entire surface of your first finished prototype If your product has a metal enclosure pay special attention to openings areas around buttons LEDs LCDs connectors or vents If the enclosure is made of plastic it is essentially transparent to electromagnetic emissions Connect all cables that are normally con...

Страница 26: ...ed on cables connected to the product Excessive electromagnetic emissions may interfere with the normal operation of other products Locating the sources of such emissions can help to restore normal operation The 3M ScanEM QC Electromagnetic Near Field Probes deal with both radiated and conducted emission Near Field Primer The measurements done for agency approval are performed at a distance of thr...

Страница 27: ... of offensive radiation But how good and reliable are these tests and how does one interpret their results Since near field readings are greatly dependent on the geometry of the source and its properties any attempt to provide a correlation between near and far field measurements will not deliver usable results The only correlation is that in general the stronger the field near the source the stro...

Страница 28: ...blem areas down to a single seam of enclosure or specific cable ESD Primer Electrostatic discharge is an electromagnetic phenomenon Electrostatic discharges or ESD events create very electromagnetic waves of short duration as short as 1 nanosecond Due to a wide frequency range of 3M ScanEM QC probes it is possible to observe ESD events using a high speed oscilloscope Connect the output of the Scan...

Страница 29: ...ge batteries as needed Keep your ScanEM QC Probes in the protective case when not in use Changing Batteries ScanEM QC probes come with the batteries installed Normally they should last several months ScanEM QC Probe takes two AAA alkaline batteries You will need to change batteries If LEDs are getting dim and or the overall performance of the ScanEM QC Probe deteriorates At least once a year If yo...

Страница 30: ...the top half of the enclosure Pay special attention not to break wires of the 3M ScanEM HQC Probe s antenna Carefully remove the old batteries and discard them Install new batteries Observe correct polarity Do not touch internal parts other than the batteries and the battery holder Close the case and replace the screws Do not overtighten them as it may damage the enclosure Tighten the connector nu...

Страница 31: ... is perpendicular to the surface of the tested area Sometimes EM fields change with time depending on what is going on inside your product In this case the ScanEM QC Probe will reflect those changes which may make it harder to zero in on specific points of high emission The LED bar lights up but there is no sound The Sound switch should be in the On position to the right All LEDs are on and the so...

Страница 32: ...proportional to the field strength Connector SMB Dimensions approx 7 31 x 1 21 x 0 76 186mm x 31mm x 20mm 6 05 x 1 21 x 0 76 154mm x 31mm x 20mm Weight approx 2 3 oz 70g Batteries 2 AAA included All specifications are for reference only All specifications are subject to change without notice Specifications The 3M ScanEM QC Electromagnetic Near Field Probe produces warbled sound Quite often electro...

Страница 33: ...ent any product is proven not to conform with 3M s Regulatory Information Sheet then 3M s entire liability and buyer s exclusive remedy will be at 3M s option either i replacement of product with a conforming product or ii refund of the purchase price paid by buyer for each non conforming product within a reasonable time after written notification of said non conformance and return of said product...

Страница 34: ... resistors 电阻电镀部 Plating in resistors 连接器 Connector 三极管 Transistor 电感器 Inductor 电磁干扰滤波器 EMI filter 装置的焊接部 Solder in instrument IC焊接部 Solder in IC 表示该有毒有害物质在该部件所有均质材料中的含量均在SJ T11363 2006 标准规定的限量要求以下 Indicates that this hazardous substance contained in all of the homogeneous materials for this part is below the limit requirement in SJ T11363 2006 表示该有毒有害物质至少在该部件的某一均质材料中的含量超出SJ T11363 2006 标准规定的限量要...

Страница 35: ...35 ...

Страница 36: ...contrary statements contained on your purchase order shall have no force or effect unless expressly agreed upon in writing by an authorized officer of 3M Warranty Limited Remedy Limited Liability This product will be free from defects in material and manufacture for a period of one 1 year from the time of purchase 3M MAKES NO OTHER WARRANTIES INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF ME...

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