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[AI5BC]

So I’m confused. Are you saying no as in “not at all will it terminate the antennas length” or “no, it will significantly “shorten” the antenna length”

What I am saying is it does not matter. If the wire is insulated, you would not terminate anything. If the wire is bare, by default it is terminated by incidental contact, but no intentional or made termination.

Does it matter which wire you use, bare or insulated? Nope.  At the end of the day, you tune it like every other dipole.

[KB1GMX]

Those that said no are wrong.
Those that said yes, but... are correct.

Thost that insist no, build it and ye shall learn.

The yabut, the coil usually does not really have much effect as
its at the high impedance end.  The shear bulk of the winder
looks more like a capacitive end plate and electrically lengthens
the wire.  Its calculable but varied with frequency and type of
insulation plus the winders diameter.

Net effect, you wind in a little more and its tuned.

I designed such an antenna package, at full length is was bog standard
dipole but slightly shorter dye to the reel (small amount of metal).  Wound
up you took off about 3% (give or take, band dependant) for the lump at
the end.  The reel served as insulator as well.  Worked as expected for
dipole and no measurable difference from a cut to length dipole for the
given frequency.

We use the twist back the wire on itself to shorten and tune antennas.
Then why not a reel?


Allison

[K5LXP]

If I want to work 40m and unwind to the 40m resonant length, and the rest of the wire remains coiled on the wire winder,

The advice that the spooled wire appears capacitive is correct. I see it even just folding a short length of wire back on itself. How much of an influence that would be on 7MHz is likely small unless it's a really big spool.  Practically speaking even if it's light gauge wire, two spools with ~67 feet of wire on them represents a weight you'd have to suspend that's not doing anything for you, so my advice is to have a connection at that point you can then deploy whatever size of dipole you need.  Fishing tackle snap swivels to join sections and faston wire terminals are lightweight and easy to manage in the field.  Or as I have often done, tie wires together with a knot and twist the bare ends together.

Mark K5LXP
Albuquerque, NM

[KF4ZGZ]

Well, yes it terminates ... it's the end of the wire.
BUT, it does change things.
The coil ( for lack of a better term with covid foggy brain ) becomes a lumped value.
I seem to remember it becomes a lumped capacitance, but don't quote me on that.
The self resonance of the lump can act as a coil or a trap .... it really just depends on how much wire and if it's bare of insulated.
Simple thing is ..... you still lengthen or shorten as needed to tune it.