Hi Howard and all: 

According to Tom W8ji, the guy who designed and was in charge of the ameritron AL-811 and AL-80 series prior to MFJ, 
under loading an amplifier and over loading can damage 1 part of the tube or the other. 
This makes no since to me as you can't graft parts of tubes together to make a good 1. LOL 
I do get it a little that under loading can put unnecessary strain on tube components. 
Theres a balance there that has to be met. Can't explain it but it makes a little sense. 
What puzzles me though is the camps. 1 group says you can under load an everything be fine while another says you can't. LOL 
On dipping my plate on my 102 using the TW-1, maybe its my meter, maybe its me, 
when I reach the peak pitch for max power, I can still rotate my plate control a little bit more before the pitch begins to decrease. 
Like going up 1 side of a bridge, crossing the top and going down the other side. While I'm crossing the top, there's no increase in power but the current is still going up. 
I didn't know this of course until I got my XYL to look over my shoulder this past weekend when tuning up my 102. 
My amp on the other hand has a shorter bridge top, that's what I'll refer to it as. Somewhere in the middle of both tops, there's a slight ripple in the tone. 
Perhaps this is the dip? At any rate, I'm now using my 102 with the load below 3 instead of 6 and my plate is between the 275/300 mark, 
spec say 300MA max and I'm getting 150W key down. 
With my load at 6 and a plate current of 350, I was getting an extra 25/30W. 
Not worth it as I would reduce an run an amp. 
That to was a problem as I didn't have things properly loaded up for the power I was driving the amp with. 
Not to mention the 102's SSB drive is controlled by the mic-gain. 
So I'd tune up in CW, switch to SSB and of course everything went out the window. 

73: 
Mike DE VO1AX