Dumb question?
 

I was having a discussion with another ham about dipoles and dipole
lengths, and a rather silly question came up that neither one of us was sure
of the answer. If a dipole is using INSULATED wire, can the electrical
length be altered by just wrapping the ends more or less around the antenna
wire when attaching the end insulator? Or does the INSULATED wire need to be
cut? He thinks it does shorten the dipole, I say it doesn't. Hope he is
right, it makes 'pruning' dipoles a lot easier.

Thanks

--

*********************************
Jim & Pat Leder
http://home.fuse.net/k8cxm
*********************************

Simplest way is to just thread the wire thru the insulator and and twist the
ends together. Since a dipole never ( well, rarely) comes out exactly right
anyway, you're gonna end up pruning/lengthening it anyhow. If you do twist
the wire back thru the insulator, yes, it will affect the length. If you
are talking about cutting the internal (radiating element) wire SHORTER than
the insulation, that doesn't make sense; the insulation is not strong enough
to hold the thing. So, just thread the wire thru the insulator and twist
the ends back onto itself. Then prune/lengthen as needed to resonate.

73

K4KWH
"Jim Leder" wrote in message
.. .
I was having a discussion with another ham about dipoles and dipole
lengths, and a rather silly question came up that neither one of us was
sure
of the answer. If a dipole is using INSULATED wire, can the electrical
length be altered by just wrapping the ends more or less around the
antenna
wire when attaching the end insulator? Or does the INSULATED wire need to
be
cut? He thinks it does shorten the dipole, I say it doesn't. Hope he is
right, it makes 'pruning' dipoles a lot easier.

Thanks

--

*********************************
Jim & Pat Leder
http://home.fuse.net/k8cxm
*********************************

On Sun, 12 Sep 2004 11:41:20 -0400, "Jim Leder"
wrote:

I was having a discussion with another ham about dipoles and dipole
lengths, and a rather silly question came up that neither one of us was sure
of the answer. If a dipole is using INSULATED wire, can the electrical
length be altered by just wrapping the ends more or less around the antenna
wire when attaching the end insulator? Or does the INSULATED wire need to be
cut? He thinks it does shorten the dipole, I say it doesn't. Hope he is
right, it makes 'pruning' dipoles a lot easier.

Thanks

I just remove a foot or two of insulation from the end of the wire,
before threading it through the insulator, and wrapping it back upon
itself -- that's possibly stronger mechanically, and avoids your
question completely :-)

bob
k5qwg

"Jim Leder" wrote in message
.. .
I was having a discussion with another ham about dipoles and dipole
lengths, and a rather silly question came up that neither one of us was
sure
of the answer. If a dipole is using INSULATED wire, can the electrical
length be altered by just wrapping the ends more or less around the
antenna
wire when attaching the end insulator? Or does the INSULATED wire need to
be
cut? He thinks it does shorten the dipole, I say it doesn't. Hope he is
right, it makes 'pruning' dipoles a lot easier.

Thanks


Good question...

Its not clear what you have in mind, but -

Doubling an antenna wire closely back on itself over a short length has the
effect of shortening overall length of the antenna just as if the the
doubled-back portion has been cut off.

Where the wire is double it behaves as a single wire of slightly greater the
diameter.

Jim,
It does shorten the antenna. Not exactly as much as if the 'extra'
wire were cut off, but close enough for 'gumment' work. The
difference won't make enough difference at HF to make a difference.
'Doc

It is kind of hard to describe, but I guess 'doubling it over' would be
closest. I've always cut extra length off, but the downside is cutting too
much off. I ask this question because of a discussion we had about dipoles:
I have an Alpha Delta DXEE that is near worthless on 40, but I would sure
like an easy way to attempt to get it resonant on 30, without cutting the
end 40 meter wires. My friend suggested just 'doubling the wires over on the
ends to see if I could shorten it enough to get it in close. My club has an
antenna analyzer, so I may give it a try.

Thanks


"Reg Edwards" wrote in message
...
Its not clear what you have in mind, but -

Doubling an antenna wire closely back on itself over a short length has
the
effect of shortening overall length of the antenna just as if the the
doubled-back portion has been cut off.

Where the wire is double it behaves as a single wire of slightly greater
the
diameter.

"Jim Leder" wrote in message
.. .
I was having a discussion with another ham about dipoles and dipole
lengths, and a rather silly question came up that neither one of us was
sure
of the answer. If a dipole is using INSULATED wire, can the electrical
length be altered by just wrapping the ends more or less around the
antenna
wire when attaching the end insulator? Or does the INSULATED wire need to
be
cut? He thinks it does shorten the dipole, I say it doesn't. Hope he is
right, it makes 'pruning' dipoles a lot easier.

Thanks

A quick and dirty I learned for putting up temporary dipoles. Mount the
insulator a good bit short of the end of the antenna. Then when you prune
for resonance you will not have to keep removing and reinstalling the
insulator.

It does not need to be cut, just wrap it around itself on the insulator
side.

Butch KF5DE

Jim Leder wrote:
I was having a discussion with another ham about dipoles and dipole
lengths, and a rather silly question came up that neither one of us was sure
of the answer. If a dipole is using INSULATED wire, can the electrical
length be altered by just wrapping the ends more or less around the antenna
wire when attaching the end insulator? Or does the INSULATED wire need to be
cut? He thinks it does shorten the dipole, I say it doesn't. Hope he is
right, it makes 'pruning' dipoles a lot easier.

Thanks