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Old May 23rd 06, 11:33 PM posted to rec.radio.amateur.homebrew
Steve N.
 
Posts: n/a
Default Best Way to build a calibrated S meter


"Caveat Lector" wrote in message
news:64Gcg.177511$bm6.76448@fed1read04...
Will take a look at URL:
http://www.ac6v.com/sunit.htm


Maybe the National Semiconductor NE604 IF amplifier IC would be worth
looking into. Claims say it provides an accurate signal strength

logarithmic
output that closely tracks the input signal level over a wide dynamic

range
that could possibly be used for driving an S meter circuit.

--
CL -- I doubt, therefore I might be !



This is ok, but the one thing is that any Signal strength IC like the 604
has a constant slope and the S-Meter will be rather compressed in the 0-9
s-units range compared to the over S9 range (obviously fixable with meter
scale). I don't recall the 604's dynamic range. You could make a two slope
correction above S9, but I'd have to do some scratch paper work to figure
out the circuit [ probably as simple as a resister and diode in the right
place]. Or use two of them and change the gain into one to get the
different slope. I don't recall the 604's dynamic range. I have some
SLx16...oops can't remember the numbers (? 1316?... 1613? ) , that are
cascaded for large dynamic range log amps.

Just some ideas.

73, Steve, K9DCI