Some more AGC measurements.
Using an HP8654B signal generator I am able to get stronger signals, ranging up to S9+40 on the K3's meter. Supposed output from the signal generator ranges from 11,000 uV for S9+40 to 110 uV for S9 to 0.32 uV for S1.
K3 AGC Measurements (repeated)
In comparison to previous measurements, we can see the hardware AGC starting to kick in about S9+20 or so.
Kenwood TS850 Measurements:
Next up, we measure W7LRs venerable TS850. Using the same signal inputs and measuring the audio output at the headphone jack with a Tektronix TX3 DVM (which shows dBmv), we see the following:
Combining the Two Curves:
Combining these two charts seems to show that the TS850 AGC starts to be effective just a few dB (3 uV vs 11 uV) higher than the K3's. Also, once the 850's AGC kicks in, the transfer function is really flat. In theory we should not hear much difference in signals ranging from about S7 to S9+40 dB.
Next up -- maybe Bob's TS590??