EM-7530 Meter, Magnetic Field Strength

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EM-7530 Meter, Magnetic Field Strength Specifications Electrical Special Features Full operation from either front-panel controls or from computer via GPIB for maximum versatility.

1 EM-7530 Meter, Magnetic Field Strength Specifications Electrical Special Features Full operation from either front-panel controls or from computer via GPIB for maximum versatility. Special compact highly-sensitive magnetic sensors sharing EM-7530 front-end circuits for measurements previously not feasible. LCD readout of magnetic field strength directly in db (pt) for optimum accuracy, plus analog meter for monitoring amplitude response. Push-button LED-indicated choice of nine lower-limit and nine upper-limit bandpass cutoff frequencies for enhanced analytical capability. Push-button LCD-indicated selection of notch filtering at fundamental and third harmonic of power line frequency to eliminate power frequency problems. Internal rechargeable battery for independence from external power sources and enhanced application to site surveys. Frequency Coverage: 20 Hz-50 khz Bandpass-Determining Filters: 20, 100, 200, 500 Hz 1, 2, 5, 10, 20 khz Lower Limit -3 db): 100, 200, 500 Hz 1, 2, 5, 10, 20, 50 khz Upper Limit -3 db): 60 and 180 Hz 50 and 150 Hz, optional Selectable Notch Filter: 40 db minimum rejection at each frequency with MF-01 Sensor Probe: 13 db (pt/ Hz) Sensitivity: 20 Hz-50 khz: 60 db (pt) Amplitude Accuracy: Within ± 2dB Amplitude Indicators: Digital: 3-digit LCD showing magnetic field strength in db (pt) Analog: 1-inch uncalibrated, for relative response Specifications subject to change without notice. Unless otherwise specified, product is manufactured in Johnstown, NY USA. Ref:

2 EM-7530 Meter, Magnetic Field Strength Specifications Analog Output: Type BNC, with output corresponding to frequency and amplitude of probed magnetic field Rear-Panel Connectors: IEEE-488: 24-pin, for GPIB connection External DC Input: 3-pin, for connection of 40 VDC power AC: 3-prong, for connection of AC power Power Requirements: AC: VAC, Hz VAC, Hz DC: Internal rechargeable battery pack operating for approximately six hours before recharge Or External DC supply of ma Mechanical Physical Characteristics: Height: 133 mm (5.25 ) Width: 222 mm (8.75 ) Depth: 368 mm (14.5 ) less handles Weight: 9 kg (20 lbs.) Environmental Capabilities: Designed to meet MIL-T-28800C Type III, Class 5 Style E environmental requirements Temperature: Non-operating: -40 C to +75 C Operating: 0 C to +50 C Relative Humidity: 95% from 10 C to 30 C 75% from 30 C to 40 C 45% from 40 C to 50 C

3 Specifications Altitude: Non-operating: 12,000 m (40,000 ft.) Operating: 3,050 m (10,000 ft) Vibration: 2 g Shock: 30 g Sensor Probes: Furnished: MF-01: Maximum sensitivity; calibrated for fields db (pt) Optional: MF-02: Calibrated for fields db(pt) MF-04: Uncalibrated for localizing sources MFEF-01: Active Calibrated E-Field Sensor

4 EM-7530 Meter, Magnetic Field Strength Description The EM-7530 Magnetic Field Meter is designed specifically to measure low-level magnetic fields at frequencies from 20 Hz to 50 khz, in accordance with procedures and limits mandated by MIL-STD- 461, MIL-STD-462, and other EMI-compliance documents, both military and commercial. The EM-7530 differs from the EM-2110A and other interference analyzers covering the same frequency range in that, in lieu of continuous selective tuning, it provides broadband operation with bandpass characteristics controlled by selection of low-pass and high-pass cutoff frequencies. Also, the EM-7530 is designed for operation with special magnetic field sensors which incorporate frontend elements to provide superior sensitivity and directional characteristics despite their small size. These differences permit applications not possible with other instrumentation and make the EM-7530 ideal for investigation of magnetic field leakage and other detailed analysis of EMI radiated magnetic fields. In addition to the standard MF-01 probe furnished with the instrument, three optional sensor probes, as covered on page 6, are also available for use with the EM Microprocessor control of all operating functions and digital outputs for all responses to input signals permits the EM-7530 to be exercised completely either from its front panel or from an external computer, via the IEEE-488 General Purpose Interface Bus (GPIB). The numerous parameters available for control and monitoring are illustrated and described on the following paragraphs. Basic operating principle of the EM-7530 is that of a variable-magnetometer, with its response directly proportional to the strength of the field being intercepted by the sensor being used. The ferrite material in the sensor exhibits a change in permeability with any change in the strength of the magnetic field in which it is immersed. This change in permeability is used to affect the inductance of an element in the oscillator tank circuit located in the sensor, thus producing a shift in output frequency corresponding to any change in the magnetic field. The FM signal thus produced by any timer-varying magnetic field present is then demodulated and calibrated to obtain a voltage proportional to magnetic field strength; it is then used for front-panel meter display and converted to produce a digital output. Frequency response of the servo circuit used to feed the analog voltage back to the sensor for stabilization is tailored to make EM-7530 operating independent of the earth s magnetic field. The EM-7530 has excellent stability and front-panel/remote control for selection of passband, notch filters, gain, and attenuation. The selected passband limits are displayed in khz on a digital LCD panel meter. Signal amplitude is displayed both on a three-digit LCD panel meter calibrated in db (pt) and as a relative level on an analog meter. Noise floor of the EM-7530 over its operating range of 20 Hz to 50 Hz is lower than 4.5 pt/ Hz, or 13 db(pt/ Hz).

5 EM-7530 Meter, Magnetic Field Strength Description The EM-7530 is complementary to the Electro-Metrics EM-2110A Interference Analyzer and can be used with it as a special sensor. In this mode of operation, the EM-7530 provides its highly-sensitive wide-band, flat frequency response (with power-frequency notch, if desired) for intercepting magnetic fields, while the EM-2110A provides the frequency selectivity, tenability, and detector functions appropriate for analyzing them. Several unique advantages of the EM-7530 make it the ideal choice for a variety of applications: Near-Field Measurements Although valuable for measurements of magnetic fields at any location, the compact size of the probes which are an integral part of the EM-7530 makes it particularly suited for the measurement of magnetic fields in confined spaces and within the near-field region of an emitter, where the electric and magnetic components are usually neither planar nor orthogonal. Narrowband and Broadband/Impulsive Measurements Broadband measurements can be made without any auxiliary equipment, using the low- and highpass filters built into the front end of the EM-7530 to establish the passband of interest. Where narrowband measurements of magnetic field are required, such as to establish degree of compliance to limits of MIL-STD-461, the EM-7530 must be augmented by a selective voltmeter or EMI analyzer, such as the EM However, the EM-7530 provides a unique advantage when used in this fashion in that the combined response with its associated sensor probe is flat versus frequency over its entire range of operation. Advantage over Loop Sensors The flatness of response obtained when using the EM-7530 avoids two unfortunate consequences of using loop sensors: the drastic fall-off in sensitivity at low frequencies and the resultant differentiation and distortion of any impulsive signals. Thus, the EM-7530 with its flat response becomes the ideal instrument for characterizing the structure of any magnetic field, regardless of both near- or far-field considerations and the type of emission being measured. Use of the optional current probe applies the EM-7530 advantages to the measurement of EMI currents. It provides high sensitivity and its flat response over the entire frequency range from 20 Hz to 50 khz avoids the differentiation of impulsive signals. These inherent advantages make the EM-7530 the ideal instrument for certain specific applications such as measurement of shielding effectiveness, especially at frequencies below 500 Hz. Its superior sensitivity permits the use of lower power in the transmitting source for such measurements, and the compact size of its probes permit more detailed mapping of the topology of the shielding barrier leakage field.

MAGNETIC FIELD STRENGTH METER MODEL EM-7530

INSTRUCTION MANUAL MAGNETIC FIELD STRENGTH METER MODEL EM-7530 INSTRUCTION MANUAL THIS INSTRUCTION MANUAL AND ITS ASSOCIATED INFORMATION IS PRO- PRIETARY. UNAUTHORIZED REPRO- DUCTION IS FORBIDDEN. 1996