I assume that DE is the driven element, right?
What is the diameter of the brass part of the stub?
1/8"
The brass stub comes pre bent and is 18" long from bent end to center of wire eyelet.
The brass part is said to be 18" inches less 1/4" for bending. What is the space between the plastic brackets that support the brass part? I don't find a dimension for this space and the image looks like the space is more than 18" inches so some of the wire is also between the first 2 plastic offset brackets. So I'm guessing there to be about 1" of wire inside these brackets as well as the brass part.
I'm getting only 137.175" inches of wire, and maybe 1" more, including the brass part out to the radiator and my wire #20 is 47" inches just like you note above. I can't account for the extra length you reported.
The image on page #7 of your manual looks like these two plastic end brackets should end up close to 4" inches inside of Dr and 4" inches inside of D1. My model agrees with your note above for the space between Dr and D1...which I have as 56" inches. 56 - 4 -4 = 48" inches and that is close to your note of 47" inches.
I hope this makes sense Dennis.
This said however, does not fix the match of my model, not even close. So I'll wait until you get the antenna built, and not bother you further with dimensions. My idea for a physical matcher for this design might not work at all as specified in the manual.
I attached a zoomed-in image below of the feeder I added to the model for the horizontal polarity only. I also added the dimensions used for the tuning stub wires including the overall length I get.