[Elecraft] S meter calibration

[Ron D' Eau Claire]

> Technically that is true, but there are indeed some historical connections
> between the two, suggesting that S-meters were originally calibrated (and
> named) after the S in RST.
> Jonathan K1RFD

The National SW-3 (ca. 1940) featured "...the volume control is calibrated
from one to nine in steps corresponding to the R scale."

That's from their advertisement in the 1941 ARRL handbook catalogue section.

What could be simpler? Turn up the audio so the signal is at "normal"
listening volume and read the signal strength right off of the volume
control knob.

Of course, that was before AGC. And with AGC came the S-meter. Indeed, the
SW-3 was a TRF receiver with a regenerative detector.

Ron AC7AC
K2 # 1289