On Wed, 10 Dec 2003 13:17:55 -0600, 'Doc wrote:



Yuri,
The reason I can't agree with the 5% thing is that I haven't
measured it, not that the number is correct or not. There is
a difference in length when using insulated/noninsulated wire,
I just can't say exactly what that difference is.

Since the environment in which the antenna is mounted/hung influences
the resonant frequency, I've never been able to see any difference
between insulated and bare copper wire.

As the things have never come out according to the formula, "for me"
I just "cut long and trim to fit".

I put up two 75 meter half wave sloping dipoles. They were cut
identical and even used the same make and model of balun. The coax
cable was the same length (LMR-400). Both were mounted at the same
height with the ends the same distance from the tower and ran at the
same angle. One ran to the NE to within about 30 feet of some trees.
The other ran to the south west over an open yard. Both worked well,
but there was between a 50 to 75 KHz difference in the resonant
frequency. The one over the open yard being the higher.

I didn't prune them as I use a line tuner to get the full band
coverage any way.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair?)
www.rogerhalstead.com
Return address modified due to dumb virus checkers

Since any calculation is only going to be approximate
(depending
on how/where the antenna is mounted) trimming is almost always
going
to be required. Since that 'tweaking' would take care of the
difference in insulated/noninsulated wire, I just haven't
bothered
about figuring it. If you have, then good, I don't have a
problem
with that...
'Doc