_____
From: Bob Richards [mailto:[email protected]]
Sent: Thursday, June 14, 2007 6:25 AM
To: ieee
Subject: GR1089 conducted calibration
No response from the first post, so I am reposting. Seems like the more
complicated the question, the more responses we get. This question must be too
simple. :-)
The GR1089 Conducted Immunity calibration is to be performed in a 50 ohm
fixture, terminated on one side with 50ohms, the other side through an
attenuator (also 50ohm impedance) to a measurement device. The test limit at
10khz is listed as 89 dBua. The calibration level, measured at the output of
the calibration fixture, should therefore be 123 dBuV ( add 34 dB to convert
>from dBuA to dBuV in a 50 ohm system). My question is this: Is there is a 6
dB adjustment in level to be included in the measurement? I have always
calibrated without any 6dB adjustment (more severe test), but the question
came up recently so I thought I would ask the question here.
Bob Richards, NCT
Bob:
I didn't think I was the best person to help you, as I'm not familiar with
GR1089. OTOH, this sounds exactly like the MIL-STD-461E Method CS114 (which I
have done a few times).
Figure CS114-3 shows the calibration setup. (461E is free; either dl it
yourself or I'll send you a PDF of it.) Paragraph 5.12.3.4.b gives the
calibration procedure. If you require 89 dBuA of current flowing in the
conductor, this is equivalent to 123 dBuV in the cal jig 50-ohm system. (Both
the Microsoft calculator and my cherished old Honeywell circular Signal Level
Conversion slide rule confirm this. <g>) Assuming that you put a 30 dB
attenuator on the analyzer side of the jig, then the output to the SA is 59
dBua (93 dBuV or -14 dBm).
This procedure simply finds that X dBm of RF drive to the injection probe
yields 89 dBuA injected current in a 50-ohm system. There is no mention of any
6 dB adjustment, either up or down.
Ed Price
<mailto:[email protected]> [email protected] WB6WSN
NARTE Certified EMC Engineer & Technician
Electromagnetic Compatibility Lab
Cubic Defense Applications
San Diego, CA USA
858-505-2780 (Voice)
858-505-1583 (FAX)
Military & Avionics EMC Is Our Specialty
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