[etech]

I usually inject the 456kc signal at the 1st detector grid (grid cap of 6L7G). However, I get the same results by injecting at the antenna terminal for that matter. If you are looking at the avc signal on the grid of the eye tube, you could be loading the avc down. That is very high impedance at that point. I do not usually tune the radios with the avc voltage. I usually use the Tektronix 465 scope and probe the plate of the 6H6 2nd detector and peak for maximum 456kc signal. As an alternative, I probe the 6F6 plate with the scope and peak for maximum demodulated audio (1000hz tone from signal generator). The radio peaks pretty close to the same both ways. I think you are getting deceptive readings because you are loading the avc circuit with your meter. If you don't have an o'scope, put your multimeter across the speaker voice coil and peak for maximum demodulated audio that way. Let me know what happens.

Ed