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

[2002tii]

Ed wrote:

>I'm referring to figure 41, p75 of TM 11-856A.  The graph shows a 
>linear plot starting at 20 dB=10 uv, and extending to 100 dB.  If 
>you extend the line through 0 dB, it passes through 1 uv.  Perfectly 
>reasonable, except my radio never followed the curve to within 20 
>dB, and I expect they were all the same.  Mine was wildly 
>optimistic, and that's what your NAVSHIPS reference says.  So that's 
>why I think the Fig 4 graph disappeared, never to be seen again. But 
>based on the graph I think the Army would have liked the radio to 
>satisfy that scale within some degree of accuracy.
>Having said that, I'll stand corrected that S9 should be closer to 50 dB.

Sure enough, right there under my nose.  I wonder whether the graph 
accurately expresses the design intent but the actual design missed 
the intent by 20 dB, or the graph was just drawn wrong?

Best regards,

Don