I have an unused attic crawlspace in which I can potentially install a 2-element 20 meter yagi. I know that adding the reflector will drop the feedpoint impedance of the driven element below 50 to 70 ohms, requiring some sort of matching scheme to reduce the SWR on the (unbalanced) 50 ohm RG-8U feedline. I have an MFJ antenna tuner (unbalanced), a quantity of fairly heavy-gauge solid aluminum wire, and a 1:1 balun on hand that I can use, and a radio (Yaesu FT-450) that wants to drive an unbalanced transmission line. I've also got a roll of 450 ohm window twinlead line in my deep stash somewhere... What is my most foolproof option (as an inexperienced operator) for performing the impedance match to an unbalanced line, assuming such a thing exists?
The transmission line run from the shack to the antenna feedpoint will be short, on the order of 15 meters total, and I can borrow an MFJ-259 antenna analyzer.