[TenTec] AGC Threshold Increments

[Kim Elmore <cw_de_n5op@sbcglobal.net>]

As I was adjusting the AGC for 80 m (noisy) I found that the 
increments of threshold adjustment get very coarse as the threshold 
is increased. For example, near the end of its range, it progresses 
(in uV) as: 7.22, 9.12, 11.26, 14.73, 21.28, 38.30, 191.48 (the max). 
I know that I can set it for almost any arbitrary value between these 
numbers using Ham Radio Deluxe and (I'm certain) N4PY's 
software.  These are not equal steps in dB; why do the adjustments 
get so coarse using the old-fashioned knob? Is there a way to 
adjust/affect this behavior?
Kim Elmore, N5OP