I wrote:
>Grant, I don't believe the 331A is True RMS.
My memory is correct!
"The Agilent 331A uses the average-responding detector. This type of
detector is calibrated to indicate the rms value of a signal (1.11
times the average value of the rectified waveform). However, this
gives a true rms value only when the signal is a pure sine wave. When
the signal is a complex waveform, or when noise is present, the
average detector almost always reads lower than a true rms detector.
With noise or harmonics present, the ratio of true rms to average is
no longer the same. "
http://www.home.agilent.com/cgi-bin/pub/agilent/library/cp_LibraryFAQDetail.jsp?NAV_ID=-536895247.536881790.02&LANGUAGE_CODE=eng&CONTENT_KEY=1000003165%3aepsg%3afaq&ID=1000003165%3aepsg%3afaq&COUNTRY_CODE=US
73, Bill W4ZV
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