[R-390] R-390A dB meter as as "S" meter

[Gord Hayward]

I'm a bit of a heretic here.  I  set the signal generator to give me 
.05V (thats as low as it will go - its a Stanford synthesized unit)
and use a pile of attenuators to get 50 uV into a 52 ohm terminated 
line.  This goes to an LH0066 damn fast buffer so that there
is no interaction between the input circuits and the attenuator chain.  
I use a few other voltages and attenuator settings to build a
calibration curve.  On one set (not a 390) I turned the meter face over 
and made my own scale.  As near as I can tell from this
procedure, the carrier level meter on my 390A  reads exactly what it is 
supposed to.  Of course the S meter calibration is only
good at one frequency and gives the voltage at the antenna terminal of 
the receiver.  Mismatches are not included in the
calibration, so a bad signal report may be mostly my own fault.

Cheers, Gord VE3EOS

-- 

Gordon L. Hayward, Ph.D., P.Eng.,
Associate Professor, Biological Engineering,
School of Engineering, University of Guelph,
Guelph, Ontario, N1G 2W1.