Cecil Moore wrote in message ...
Brian Kelly wrote:
A pair of caps
mechanically coupled via an insulated shaft coupling but completely
isolated electrically from each other should work.

Yes, that's what I had in mind. Mine are side-by-side with a
non-conducting fiber-chain connecting the shafts. Same with my
two rotary coils. When I said "dual-ganged", I meant mechanically
ganged, not electrically ganged.

| |/
Coax center wire--------|/|--------feedline--------
/| |
ganged variable caps to dipole
| |/
Coax braid--------------|/|--------feedline--------
/| |


OK , I got off on the wrong foot, this is more better. Tnx for the
clarification. Now back to Autocad so that I can enshrine it for
posterity . .

There are a lot of nice inexpensive instrument-quality parts out there
which make it quite easy to mechanically couple variable caps, rotary
inductors and I guess even pots but I've never seen that done. I'm
partial to the miniature timing belts and gears. IF they're not
wire-reinforced belts. For this tuner job there are plenty of options
available.

I had a monster remotely controlled tuner in the back yard for years
for my end-fed 135 inverted L. I used a pair of old WW2 Navy gun
director synchros, one in the shack which I cranked with a turns
counter and the other in the tuner cabinet to spin the big rotary
inductor via a small timing belt, never missed a lick.

w3rv

(N2EY) wrote in message . com...
(Brian Kelly) wrote in message . com...
Cecil Moore wrote in message ...


The books give all sorts of figures for "open wire line". But many of
them are for the classic lines made of #14 copper spaced 4 to 6 inches
with ceramic spreaders every few feet. Brown poly TV twin lead with
rectangular holes punched in it is a whole 'nother ball game.
'Specially at high SWRs and when it's wet. Which may not be a
consideration in NTX but is a big consideration in EPA.

(a) It's only Field Day
(b) If ya just gotta have "the real thing" it's out there for cheap:

http://www.w7fg.com/ant.htm

It can be coiled into a big helix as long as the adjacent coils are
a couple of feet apart. You can run an insulated rope to the antenna
feedpoint and coil the ladder-line on the rope with the coils tiewrapped
a couple of feet apart.

That's slick.

Until the rain falls or the wind blows

It rains on thousands of G5RVs every day all over the world and . . ?

or somebody walks into it in
the dark.

.. . welcome to Field Day antenna farms . .

Biggest headache, though, is switching the various lengths for
different bands.

No feedline switching involved here.

I was thinking more along the lines of sniping one of the orange
barrels which are the Pennsylvania State Flower. They're quite readily
available at construction sites along the PA Turnpike and
slinky-wrapping feedline around one of those should do the job.

Would solve the walking-into-it problem too.

The orange barrels wuz a JOKE!

The big question for any FD antenna is "how many QSOs"? All the
simulations and Smith charts don't count for any points - QSOs do.

Exactly. So ya get a bit more loss when it rains on a G5RV, who
cares?? Lemmee cite a good recent example of why too many people fuss
too much with dB. here dB. there details.

I was watching ops at the N3RS multiop station during the ARRL CW DX
contest in March. Late in the contest the guy in the 20M seat was
knocking out contacts as a respectable rate. The xcvr was an FT-1000
and the amp was a big remote-controlled ACOM. After some considerable
amount of time he finally noticed that the amp had faulted and swithed
itself offline when he changed bands to get on 20M. He'd been running
barefoot the whole time without realizing it. The problem was sorted
out, the amp was reset and off he went again this time with full
power. His rate did not change by any discernable amount even though
his "losses" went down by what . . 12 dB?

So no, I am not gonna get my knickers in a twist over the collection
of incidental losses one runs into with FD antennas and tuners. As you
imply there are far more telling factors which determine the
effectiveness of any station.

My
personal best is 629 QSOs with one 100W rig, one op, one mode, three
bands and two antennas. Coax fed trapper set up as inverted V for
80/40, quarter wave groundplane elevated 5 feet with 8 sloping radials
for 20.

Anybody here beat that on FD with only dipoles and verticals?

OK, change of topic here, I'm game. Anybody out there have well over a
hundred countries confirmed on both 80 and 40 by using just a single
length of end-fed wire for the antenna?

73 de Jim, N2EY

JGBOYLES wrote:
A G5RV type antenna in its many configurations ought to work as advertised.

:-) Hope springs eternal from the human breast. :-)

And as you have proved Cecil, it can be tweaked.

It can be tweaked to perform well on any and all HF bands.
Mine does.
--
73, Cecil, W5DXP



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Brian Kelly wrote:
OK , I got off on the wrong foot, this is more better. Tnx for the
clarification. Now back to Autocad so that I can enshrine it for
posterity . .

Don't bother with the caps. I was 180 degrees out of phase. Try
dual 3-30 microhenry rotary coils instead ... sorry about that.
--
73, Cecil, W5DXP



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Cecil Moore wrote in message ...
Cecil Moore wrote:

N2EY wrote:

Biggest headache, though, is switching the various lengths for
different bands.

No switching the various lengths on this one, Jim. Just a 110 ft
dipole fed with about 110 ft of fixed length ladder-line with two
series variable caps as the one knob tuner. Covers from 3.5 MHz to
4.0 MHz with an SWR less than 1.7:1 and no lossy coils needed.

I apologize to everyone for a mental blunder I made with this
proposed antenna. The reactances are capacitive, not inductive.
It would have to be tuned with series inductors which defeats
the propose of a low loss design.

Nothing ventured, nothing gained. Back to the G5RV . .

w3rv

In case you missed it, this thread is
about improvements that can be made to the standard G5RV,
something in which tens of thousands of hams might be
interested.
--
73, Cecil, W5DXP

That's odd, by the header I thought it was supposed to be about locating
cheap coax. I think dev/null had it right, it is a ****ing contest...


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Cecil Moore wrote in message ...
Mark Keith wrote:
I was so disgusted with the things after
the 2nd FD, I refused to ever use one again. And I haven't. I bring my
own wire and coax just to make sure I don't get stuck on one. And I
wasn't the only one complaining either...
I won't be suffering with a system efficiency in the mid 90's...

It would be easy to try my G5RV modification. For 3.8 MHz, it is
25 ft of "450" ladder-line with a 1000 pf cap in parallel at the
ladder-line/coax junction. I wish you would open your closed mind
and try it sometime.

I don't have much use for one, even if I wanted to. I'll never dump my
dipoles to change to a G5RV. I'll never use an antenna system with a
coax/choke/ladder line feed either. Sorry...But feel free, if you want
to...

I guess this is what led me to question your choice of the perfect FD
antenna. 80m, being the band of real issue.

A perfect FD antenna would allow one to change bands relatively
quickly without sacrificing performance. My G5RV does that.

The only bands I work at FD are 80 and 40 CW. I use parallel dipoles
at right angles. My band change is instant. If for some reason I get a
wild hair, and decide to try 20, I get on the beam. I never go any
higher than that, because it's always night when I operate. I don't do
anything in the daytime except set up my junk, and then lounge around
and look useless for a while....:/ I then go home, and come back later
in the night and operate when it's cooler.

The 110 ft dipole that I came up with has an SWR of less than 1.7:1
over the entire 75-80m band. That sure beats the bandwidth of a
resonant coax-fed dipole.

Who cares if I don't move more than 100kc all night? I zig zag back
and forth from 3500 to about 3600...7000 to about 7075 on 40..



That's not the old wives' tale. The old wives' tale is, "A G5RV
is a terrible antenna that cannot be improved to near perfection."
With minor modifications, a G5RV will compete favorably with any
other HF dipole on any HF band.

I guess your idea of "near perfection" is different than mine...I
agree it can be improved quite a bit, but I'll reserve comment on the
"near perfection" part...
If I wanted a multi band dipole using only one element, I would use a
80m dipole, with insulators at each point, for each band. I then use
jumpers to bypass whichever insulators I want for a certain band. I
prefer that method to yours because the feed stays at 50 ohms appx,
and the pattern is a normal dipole pattern on any band I use. To me,
this is more "perfect" than your method, as it retains my preferred
"50=50=50" policy. :)
But it's all personal preference...Below would be a 80/40/20 version,
which also works 15m on the 40 leg. I've used this method many times.


o-----------------o----------o----------00----------o----------o---------------o

But for what he originally wanted as far as covering two parts of 80m,
with one antenna, I still would prefer paralleled dipoles, cut for
each section of the band. I would run them at right angles like a
turnstile. The SWR curve will look like a "W". Solves his problem, and
is still ultra efficient with no caps to diddle, weird feedline
combos' etc..Add 40m legs, also in parallel, and it's instant
bandchange between both parts of 80, and also 40. Won't have to do a
thing except dial the radio around...I think he said he's already got
the high bands covered...To me, thats the "perfect" antenna for his
problem, and what I would run in his case. But to each his own I
guess... MK

Paul wrote:
That's odd, by the header I thought it was supposed to be about locating
cheap coax. I think dev/null had it right, it is a ****ing contest...

Subjects drift and split into different threads. If you don't like this
thread, don't read it. Simple as that.
--
73, Cecil, W5DXP



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Mark Keith wrote:
But to each his own I guess... MK

I prefer experimenting to operating.
--
73, Cecil, W5DXP




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Cecil Moore wrote in message ...
Brian Kelly wrote:
OK , I got off on the wrong foot, this is more better. Tnx for the
clarification. Now back to Autocad so that I can enshrine it for
posterity . .

Don't bother with the caps. I was 180 degrees out of phase. Try
dual 3-30 microhenry rotary coils instead ... sorry about that.

Lets not throw the baby out with the washwater, this ain't over Cecil.
In fact it opens up possibilities. Fact is that very few ops who get
on 80/75 use anywhere near the entire 3.5-4.0 segement, it's a
function of one's specific interests and reasons for using the band.
In my own case I'm a basically a DXer thus my only real interest is in
just the 3.50-3.55 and 3.70-3.85 Mhz slices of the band. And in being
able to have a single, simple antenna which presents low feedpoint
SWRs in those frequency ranges. Which rules out conventional dipoles
and most of the rest of it's relatives.

In the case of your 110 foot flattop with it's 110 foot feedline and
for my specific purposes the "tuner" would be a pair of inline lo-loss
fixed coils with taps which are selectable with a simple two pole
two-position ceramic rotary switch. Or make it a three pole switch and
be able to ground the antenna. Three taps yields three slices, etc. A
tuner like that would be a whole bunch easier to build and use and
would require much less mechanical claptrap than the original pair of
variable caps scheme requires.

However if using your 110 foot run of ladderline and coils
configuration is a hassle but a 44 foot feedline would work Mr.
Boyle's design can be used to get the same basic performance results
with the caps. The thread has produdced a couple good approaches for
practical solutions for an old problem and they both go into my
keepers book.

w3rv