[R-390] AGC problem

[DJED1 at aol.com]

I made a few measurements on my receiver to see what the AVC characteristic 
was.   I got the following curve, which shows pretty good AVC action:

microvolts in          AVC volts          audio level
5                         -1.0                    -5 dB
50                         -4.0                    -3 dB
500                    -7.0                    -2 dB
5,000                    -9.4                    -2 dB
50,000                    -12.3                    -3 dB


I was also curious about the input impedance match to the generator, so I put 
my MFJ antenna analyzer on the receiver input.   Interestingly, all readings 
at center frequency were in the range of 25 to 50 ohms, with the reactance 
being tuned out by the antenna trimmer.   I suspect I may have a bad measurement 
because the signal level is so high.   Has anyone done a similar measurement?  
 Is the receiver input really 100 ohms or so, or have we been worrying about 
generator mismatch for nought?
Ed   WB2LHI