Hi all: 

Ever since I learned how to operate tubed gear with my TW-1, 
I've never heard the pitch decrease to indicate a dip in plate. I've always used the increase or decrease in pitch to indicate an increase or decrease in forward or reflected power etc. 
I was also taught to always go for max power with adjusting the plate and load controls of an amp and then reduce the drive. 
So should I in fact hear a decrease in pitch if the plate is dipped, if so, never have heard it. LOL 
It also makes sense to set the load for an initial setting and then don't readjust it for the final tune up drive level, 
as in my case with the 811H, suggested by Tom, W8JI who was in charge of the 811 line for Ameritron before they were bought out by MFJ 
The way it was described was the 2 or 3 prior light drive loads don't do anything. 
The main thing with tubes is the grid and plate currents and keeping them below there max ratings and everything's fine. 
In the case of my 102 and amp, my outputs are below the maxes and I'm delivering specified power outputs. 
On another note, Tom wants to work with me in developing a grid announcing or tone generating device and I suggested connecting an oscillator to the amps ALC, from what I understand and it would activate when the 200 of grid current would be reached. 
Perhaps he might refine something which could include the plate current as well, if that's even possible. 

73: 
Mike VO1AX