The Electro-Metrics EM-7535 Radio Noise Meter is used to measure impulsive noise in the AM broadcast band at a single fixed frequency. The EM-7535 conforms to ANSI C63.2, ANSI C63.4, and performs the test of NEMA Pub. NO. 107 plus other associated tests which are performed on high voltage electrical generation equipment.

The standard frequencies of 834 kHz and 1.0 MHz are chosen since there are virtually no AM broadcast transmitters operating at these frequencies in the United States. Frequencies at which there is no broadcast activity are chosen because they permit high accuracy surveys to be made due to the low ambient noise present. In addition to the stated standard frequencies, optional fixed frequencies between 550 kHz and 1.5 MHz are also available on request (factory installation only) for special applications.

The receiver features 120 dB measurement range, attenuation range of 60 dB, voltage accuracy of ±2dB, plus broadband/narrowband sensitivities of 0.1µ V and 0.07 µ V/kHz respectively. A quasi-peak detection circuit, with charge/discharge rates of 1 ms/600 ms, is used to detect the amplitude level of the emissions emanating from the power distribution systems and equipment.

A front panel 5-inch (127 mm) analog meter is used to display the detected signal using either a log or linear scale. Graphic recordings can be made using a recorder connected to the front panel RECORDER Connector. A built-in speaker is available for audio monitoring of a detected AM modulated signal.

The EM-7535 can be used to make direct measurements of conducted interference via a current probe or direct connection to interference source and for radiated interference measurements using a calibrated antenna.

Specifications

Electrical

Center Frequency:
Standard: 1.0 MHz – 834 kHz
Optional: 550 kHz – 1.5 MHz
(Center frequency factory selectable only)
6dB Bandwidth: 5 kHz ±0.5 kHz
6dB Shape Factor: 3.5 maximum, 6 – 60 dB
Detector: Quasi-Peak
(conforms to ANSIC 63.2)
Rise Time: 1 ms
Discharge Time: 600 ms
Sensitivity (typical 3 dB above noise):
CW: BB: Input Impedance: 50 Ohms, nominal
VSWR: <1.2:1
Measurement Range: 120 dB (0.1 µV to 0.1V)
(60 dB meter, 60 dB attenuation)
Measurement Accuracy: ±2.0 dB
Indicating Meter: 127 mm scale (5”)

Electrical Continued

Logged Scale: 0 – 60 dB, 1 dB increment
Linear Scale: 1 – 1000 µ V
Oscillator Radiation: IF Rejection: >90 dB, standard frequencies
Image Rejection: >90 dB, standard frequencies
IF Frequency: 455 kHz
Shielding Effectiveness: AM demodulator with built-in speaker and level control
Recorder Output: 0 – 1.0 mA full scale, 1500 ohm load
Power requirements: 90 – 250 VAC, 48 – 63 Hz 5 Watts, nominal

Mechanical

Height: 133 mm (5.25”)
Width: 305 mm (12”)
Length: 337 mm (13.25”)

Product Sheet