[R-390] Another 390A Carrier meter question

[DJED1 at aol.com]

In theory, according to my manual, 0 dB is 1 microvolt, so 20 dB is 10 and  
40 dB is 100 microvolts.  So I assume s9 is a bit less than the 40 dB  mark.  
However, the scale is very dependent on the setting of the IF gain,  so unless 
you calibrate the IF gain to the meter reading, you don't know what  you've 
got.  I checked mine and found that the meter was also rather  non-linear, so I 
don't rely on it for accurate signal level measurements.
Ed