Where does one draw the line on s-meter calibration? It would not be
difficult to compensate for all the adjustments and gain variations of the
receiver and convert actual microvolts at the antenna input to a defined
s-meter reading. But that reading will not mean much if the antenna is not
standardized. A stacked 6 over 6 will be more generous than a dipole.
Perhaps the best use of the s-meter is to allow the user to estimate changes
in actual db. Years ago I ripped out my rf gain control in a receiver and
replaced it with a shielded multideck switch wired as an attenuator and
calibrated in 6 db steps giving a 36 db range at the antenna input. It was
a most useful accessory and allowed me to give reasonable estimates of
changes made by the other station.
I build a lot of portable gear (I am probably not allowed to mention qrp
here) and have found that I end up using these rigs with very poor antennas.
At first, I calibrated the s meter as accurately as possible. However, with
poor antennas, the s meter always read low. Now, I calibrate the s meter so
that a loud station pins the meter. It may not be accurate, but it makes me
feel better. Otherwise, I spent most of my time trying to change the
antenna to receive better. For portable operation out of my canoe or kayak,
S9 means I can hear them.
Colin K7FM
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