The antenna wire will be insulated, so I am wondering is I should cut them to actual length that include the overlap, instead of just cutting it for the actually physical size, determined by the formula.
Well, far be it for me to tell you what you should
do, because doing things that don't work
as we expect them to is an important part of the learning process. Either approach is just as good
in that respect...
Here are some of the quirks that make it difficult to predict the exact length of wire required:
(1) the insulation will shorten the resonant length of the wire somewhat, probably by a factor
between 1% and 5%.
(2) the formulas don't take into account the wire diameter, which affects the resonant length.
(3) the formulas don't account for the antenna height, ground type, or the angle between
the wires, all of which affect resonance as well.
(4) folding the wire back isn't the same as cutting it off, but it isn't the same as extending
it straight out, or letting it hang straight down, either.
(5) folding the wire back may be an effective way to tune the end of the outer wire, but it
isn't as practical for the inner section because you need to connect the wire to the trap.
With the wire folded back you either have to bend the end back around to reach the trap or
cut through the insulation at some point closer to the trap to make the connection.
My suggestion is to make the overall length of the center sections about a foot shorter on each
end than the formula would suggest. (The formula uses 234/f to calculate each side, which is
the same as 468/f for the total length.) Tie the wire to the insulator at this point leaving about
3 extra feet hanging down then looping back up to attach to the trap. (This can be a piece
of regular stranded copper wire for flexibility) That allows you to unsolder the end, trim off
some excess wire, and reattach the wire to the trap without having to untie the insulator.
On the very ends of the antenna I'd cut the wires a couple feet long and attach the ropes 3' to
4' in from the end of the wire. The end part can hang down and be trimmed for final SWR