[Texasrocker]

Im not sure if this theory applies to your set,most probably not if your set has avc circuit, but I have run across similar circumstances in TRFs before using a dual-type pot resistance setup. Whereas, when the wiper is turned up from the ground end of the pot, the resistance (the signal strength) increases at a slow rate for about the first 1/3 of rotation, then, much more rapid increase in volume as pot is turned all the way up to max volume.
The overall effect on the trf sets ,is that this gives a variable amt of control, slower increase at lower volume ( higher signal strength)end of pot, and a faster increase after about 1/3 of full rotation. In the trf sets,this is a early attempt to acheive "audio taper" from a linear taper design. I have the JF Riders books, I will take a look at the schemat when I get back to my workshop. I have trouble seeing the nostalgiaair pages on my small laptop. Randal