Actually, the S scale is entirely subjective. While the idea of making a 50
microvolt signal "S9" and each "S unit" exactly 6 dB is commendable, it seems
to me to be unrealizable in practice.
MOST S meters are tied to the inherently non-linear AVC/AGC/ALC (whatever you
want to call it) line. Since the source isn't linear, the meter cannot be.
And since no two radios are have exactly the same gain characteristics it's
difficult to design a meter scale that's more than a general representation
of signal strength.
Bottom line - S units are useful descriptions but are not exact. Like the
exact difference between some, a bit, and a tad.
73 Pete Allen AC5E
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