You should purchase take a look at tools that may will let you study the loop acquire and loop part properties of an working suggestions loop and, that bought tools will ship helpful outcomes over a really big selection of frequencies. Nevertheless, the suggestions loops within the energy provides I’ve encountered solely wanted to be characterised over pretty restricted frequency ranges. That being the case, going “homebrew” with some low-cost elements labored out fairly nicely.
Loop acquire and part measurements have been a lecture subject I first encountered on the Dallas, Texas PowerCon again in 1981. A presentation was made, at the moment by Dean Venable, the place I first grew to become conscious of a selected approach for the measurement of acquire and part of a suggestions loop such because the one proven in Determine 1.
Determine 1 A suggestions loop that requires testing.
We select a degree within the suggestions path the place will focus our consideration. The place the “X” is seen above, we insert a transformer and introduce a community analyzer (Determine 2).
Determine 2 A suggestions loop prepared for testing.
With malice a forethought, we select our “X” level the place the supply impedance of A1 is zero and the enter impedance of A2 is infinite. Because the inserted take a look at transformer is not going to disturb the suggestions loop’s regular operation, our acquire and part measurements might be consultant of these two parameters underneath the circumstances through which the suggestions loop will really see service.
Utilizing on the time, an Agilent 4395A community analyzer, an instrument now outdated however nonetheless a pleasant piece of electronics anyway, a “homebrew” take a look at transformer was devised as proven in Determine 3.
Determine 3 A homebrew take a look at transformer and it’s take a look at utilization.
A typical energy provide take a look at consequence obtained from this take a look at methodology seems like Determine 4.
Determine 4 A acquire and part take a look at consequence.
What the precise bandwidth of the homebrew transformer could be, I’ve no clue. Nonetheless, it’s broadband sufficient to let me get a fairly good take a look at the loop acquire and part traits of any energy provide I’ve needed to take care of but.
John Dunn is an electronics guide, and a graduate of The Polytechnic Institute of Brooklyn (BSEE) and of New York College (MSEE).
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