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RFI/EMI Current Probes and Injection Probes

Description
Specs

DESCRIPTION

CURRENT PROBES
Current probes required by various EMI specifications (such as MIL-STD-461/2) are toroidal transformers designed to measure RF currents on active power lines or other conductors.

APPLICATION
A current probe is used as a “pick-up” device for measuring RF current in single conductors or cable bundles when connected to the 50 Ω input
of a radio frequency interference measuring receiver or spectrum analyzer.

DESCRIPTION
Direct connection to the conductor carrying EMI current is not necessary, since the probe may be opened for insertion of the conductor into the window of the toroid and then closed again to form a toroidal transformer with the conductor acting as a one-turn primary.

A correction factor graph is provided to convert measured µV to EMI µAs. When the EMI current is measured in dB above 1 µV as indicated on a conventional EMI meter, the correction factor will convert the measurement to dB above 1 µA. The correction factor is the inverse of the transfer impedance, Zt. Each probe is shipped with a graph of the correction factor versus frequency, keyed to the serial number on the probe.

INJECTION PROBES
Specifications require the injection of large high frequency currents into cable bundles and individual wires, using inserted secondary toroidal transformers placed around the conductors being tested.

APPLICATION
High power RF amplifiers with 50 Ω output impedance are used to deliver voltage to the injection probe. The wire or cable through the window of the probe acts as a secondary of the toroidal transformers. This test method is intended to be used instead of earlier methods, such as CS-01, CS-02, and RS-02 of MIL-STD-461.

DESCRIPTION
Bulk current injection probes are available in two styles:
1.	Fixed window style where the wire(s) under test must be passed through the window.
2.	A split toroidal design where the probe can be opened up and clamped over the wire(s) under test.

Each probe is calibrated for insertion loss and transfer impedance in a test fixture designed for the particular window size. This fixture provides a signal path with a low Voltage Standing Wave Ratio (VSWR). A typical fixture is Solar Type 9125-1, used for probes with 32 to 44 mm diameter windows. Ask for details on this and other test fixtures.

Injection probes currently available are described later in this section. Development of new styles is ongoing. If a probe meeting your requirements is not found on the list, send us details and we will provide a solution.

TECHNICAL INFORMATION
Current probes used as receptors are known as “inserted primary toroidal transformers” for connection to EMI receivers. Injection probes which deliver high RF currents into wires through the window are called “inserted secondary toroidal transformers”.

The maximum voltage carried on wires through the window is limited only by the insulation of the wires. Maximum primary current in the wires through the window of current probes is listed in the table in the Specifications tab (symbol lp).

The signal input to injection probes is rated in W from the signal source as indicated in the table in the Specifications tab.

Development is continuing on new and useful probes, both current measuring sensor probes and high wattage injection probes. The following is a partial list. As time goes on, the list will grow. If you do not see what you need, just ask.

SPECIFICATIONS

CLAMP-ON CURRENT PROBES

					Maximum PRI. (pl) current, A
Type number	Window diameter	Nominal Z_T Ω		DC to 60 Hz	400 Hz	RF (CW)		Pulse	Frequency range
9124-1N	1.25" (32.0 mm)	0	.001	200	70	50		5000	1 kHz - 200 MHz
9205-1	1.25" (32.0 mm)	0	.33	800	800	50		100	20 Hz - 8 MHz
9118-1	1.25" (32.0 mm)	0	.10	350	150	22		500	500 Hz - 200 MHz
9134-1	1.25" (32.0 mm)	0	.70	500	400	5		100	20 Hz - 100 MHz
6741-1	1.25" (32.0 mm)	0	.70	350	225	5		100	10 kHz - 100 MHz
9207-1	1.25" (32.0 mm)	1	.0	800	450	4	.2	100	20 Hz - 150 MHz
9209-1	1.25" (32.0 mm)	1	.0	800	800	100		200	20 Hz - 30 MHz
9145-1	1.25" (32.0 mm)	5		350	350	42		100	10 kHz - 152 MHz
9123-1N	1.25" (32.0 mm)	1-5		200	200	40		60	10 kHz - 500 MHz
9214-1	1.25" (32.0 mm)	5		600	600	21		200	20 Hz - 150 MHz
9215-1N	1.25" (32.0 mm)	1-5		400	350	40		100	20 Hz - 500 MHz
9231-1	1.25" (32.0 mm)		.010	300	200	7		3000	1 kHz - 200 MHz
9219-1N	1.25" (32.0 mm)		.025	400	300	150		200	20 Hz - 20 MHz
9250-1N	1.25" (32.0 mm)		.10	200	200	10		200	10 kHz - 450 MHz
9257-1N	2.62" (67.0 mm)	4		500	500	200		200	20 Hz - 30 MHz
9258-1N	2.62" (67.0 mm)	5		500	500	100		200	20 Hz - 100 MHz
9261-1N	2.62" (67.0 mm)	2		500	500	2	.6	100	20 Hz - 200 MHz
9263-1N	2.62" (67.0 mm)		.03	500	500	80		200	20 Hz - 100 MHz
9301-1N	2.62" (67.0 mm)	8		350	350	60		200	20 Hz - 500 MHz
9303-1N	2.62" (67.0 mm)		.001	500	200	100		5000	20 Hz - 100 MHz
9305-1N	2.62" (67.0 mm)	1		500	500	2	.3	200	20 Hz - 200 MHz
9306-1N	2.62" (67.0 mm)		.005	800	300	14		5000	1 kHz - 100 MHz
9307-1N	2.62" (67.0 mm)		.005	300	300	60		5000	20 Hz - 100 MHz
21406-1N	2.62" (67.0 mm)		.01	350	350	40		2200	100 Hz - 30 MHz

We provide equivalents for most Stoddart and Eaton probes.

CLAMP-ON INJECTION PROBES

				Insertion loss
Type No.	Window diameter	Winding current	Rated W	Under 6 dB	Under 10 dB	Under 15 dB	Under 20 dB	Frequency range
9108-1N	1.25" (32 mm)	10	50	—	—	120 kHz - 70 MHz	60 kHz - 150 MHz	10 kHz - 200 MHz
9142-1N	1.50" (38 mm)	50	200	10 MHz - 350 MHz	5 MHz - 430 MHz	2.5 MHz - 500 MHz	1.5 MHz - 500 MHz	2 MHz - 500 MHz
9144-1N	1.50" (38 mm)	26	100	—	200 kHz - 8 MHz	70 kHz - 90 MHz	40 kHz - 100 MHz	4 kHz - 100 MHz
9217-1N	1.50" (38 mm)	26	100	—	200 kHz - 5 MHz	80 kHz - 100 MHz	50 kHz - 100 MHz	10 kHz - 100 MHz
9335-2	1.50" (38 mm)							10 kHz - 100 MHz
9607-1N	1.25" (32 mm)	10	50	—	500 kHz - 1 MHz	200 kHz - 30 MHz	120 kHz - 300 MHz	10 kHz - 300 MHz
9719-1N	1.50" (38 mm)	60	200	5 MHz - 100 MHz	3 MHz - 200 MHz	1.5 MHz - 200 MHz	700 kHz - 200 MHz	10 kHz - 200 MHz
2216-1N	1.50" (38 mm)	26	100	—	—	50 kHz - 30 MHz	10 kHz - 100 MHz	1 kHz - 100 MHz

Injection probes can also be used as current probes. A correction factor graph and instructions for its use are supplied.

CALIBRATION FIXTURES

Type No.	Description
9125-1	For injection probes, 1.5" (32 mm - 44 mm) diameter window. 20 Hz to 500 MHz. Type N connectors.
9125-2	For Solar 9119-1N Probe and similar, 1.25" (32 mm) diameter window. 400 MHz to 3 GHz. Type N connectors.
9251-1	For Eaton, Stoddart and Solar probes, 1.25" (32 mm) diameter window. 20 Hz to 500 MHz. Type BNC connectors.
9254-1	For Eaton, Stoddart and Solar probes, 2.62 " (66 mm) diameter window. 20 Hz to 500 MHz. Type N connectors.
9321-1	For Eaton, Stoddart and Solar probes, 0.75" (19 mm) diameter window, totally enclosed. 20 Hz to 1.5 GHz. Type BNC connectors.
9330-1	For Eaton, Stoddart and Solar probes, 1.25" (32 mm) diameter window, totally enclosed. 20 Hz ≈ 1. GHz. Type N connectors.
2925-1	Fixtures for Solar Type 9335-2 Probe. 20 Hz to 100 MHz. Type N connectors. (9357-1 has been discontinued

NOTE: Except for Type 9125-1 and 2925-1, the probes are supported and centered in the fixture.

item #	page links
7334-1	Loop Sensor, RE01, RE101
7429-1	Loop Antenna, RS01
9229-1	Loop Sensor, RS101
9230-1	Loop Antenna, RS101

item #	page links
7021-1	Phase Shift Network
7429-1	Loop Antennas
9229-1 9230-1	Loop Antennas
7115-2	Using Type 7115-2 High Voltage Transient Pulse Transformer
7415-3	RF Coupler and High Pass Filter
6220-1B	Application Note AN622001 for Type 6220-1B Transformer
	Calibration of Loop Antennas
	EMI Prediction Graph

item #	page links
various	10 µF Feed-Thru Capacitors
7525-2	Series Capacitor, 0.1 µF, BNC
9133-1	3 Phase Delta Capacitor, 10 µF
9146-1	3 Phase 'Wye' capacitor, 10 µF

item #	page links
7415-3	RF Coupler and High Pass Filter

item #	page links
2654-2	Lightning Pulse Generator
2854-2	Spike Generator
7054-2	Spike Generator, 600 V, 10 µS decay time
7054-2A	Spike Generator, 400 Vs, 50 µS decay time
7054-2B	Spike Generator, 400 V, 120 µS decay time
7399-3	Spike Generator, 2500 V, 90 µS decay time
8282-1	Transient Pulse Generator for MIL-STD-461B/C, 3 waveshapes
9354-1 9354-2	Transient Generator, dampened sine wave/double exponential
9355-1	Pulse Generator for MIL-STD-461-D/E, Method CS115
9554-( )	Variable Frequency Modules

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