On Fri, 14 Oct 2005 20:28:17 GMT, "W3JDR" wrote:

Richard,
What you said is largely accurate, however at low S/N ratios, or where the
distortion becomes comparable to the signal level, the reading of the
composite signal (signal+noise+distortion) with anything other than an RMS
meter could produce erroneous results.

Hi Joe,

In the practical world of SINAD (having tuned a number of GE and
Motorolas), one is not very interested in how poor your set is, but
rather meeting a service standard (that 12 dB which is as arbitrary as
any).

I doubt if many of the current generation of commercial surplus
equipment comes with a stock tester employing what would have been an
expensive converter chip to insure RMS measurements. I come by that
assessment by noting those I used employed standard meter movements.
The first RMS meters I calibrated in the mid 70s came from Fluke (just
up the highway), and the components of that circuit were scrubbed of
all identification numbers or cast in epoxy. Such was the cachet of
being hi-priced, and having others try to break into the market with
knock-offs.

My Radio Shack multimeter makes that claim (ca 1995) and if memory
serves, that Micronta's "True RMS" was barely capable of poor voice
grade bandwidth. This was 20 years after Fluke, costing about as much
(economic inflation), and not performing as well (technical
deflation).

73's
Richard Clark, KB7QHC