"Roy Lewallen" wrote in message
...
I haven't followed this thread very thoroughly, so this might not be
directly relevant. But it should be of interest to anyone trying to
detect small signals with a diode.

I spent a lot of time thinking about this some years ago when designing
a QRP wattmeter, and some of the conclusions I came to appear in the
resulting article, "A Simple and Accurate QRP Directional Wattmeter",
published in QST, February 1990. See the analysis on p. 20, "Ac v Dc:
Why the Difference?"

Roy Lewallen, W7EL

Your article sounds interesting. Is there a link available to see it?.
The simplest approach I've seen, was is in the 'Levell TM6A broadband
voltmeter'(UK). Designer chopped the low level diode output at 20Hz,
allowing a 1mVac FSD.
regards
john