This topic has been kicked around so much, I feel like it fits into the
upcoming spring/summer TV reruns. I currently have a G5RV in an inverted Vee
configuration, with the apex at about 35 feet. It works OK on 75/80, pretty
well on 40, OK on 20 and OK on 17. It is a miserable failure everywhere
else. I'm limited in space and height, but after surveying my trees and lot,
I could put up a 135 foot center fed doublet with the apex at about 40 feet
and the ends sloping down to about 15 feet (another inverted Vee, best I can
do with my trees). I would feed it with 450 ohm ladder line to the shack,
mate it with a 4:1 current balun and then connect with a short piece of coax
to my TS450's ATU. Seems like it should work, but I guess I need to ask some
questions:
1) My G5RV is old, and has been patched. I expect it to not survive another
winter or the vinyl eating squirrels. Does the doublet offer me any
improvements? The ladder line would be away from the hungry rodents, free
swinging and not near their trees.
2) Or, should I just rebuild the G5RV and scrape the doublet idea?
3) Is the 4:1 balun a good idea? Seems the only good way to be able to use
the Kenwood's ATU. The G5RV and Kenwood work well together on all bands,
even though it doesn't radiate out of my backyard on some of them.
4) Should I be concerned with RF in the shack with the doublet scenario?
5) Is there a better doublet length than 135 feet? That seems to be the most
common length I see.
6) My intention is to replace the RV with something better, that offers
improved performance on 75/80,40,30,20 and 17. Is it LIKELY this setup will
work, or am I too optimistic? I have an Alpha Delta DXEE which would be
moved to where the G5RV is now, offering me 20,15 and 10 (it's bad on 40).
7) I've spent a bit of time looking over my situation, and this is maybe the
best wire antenna installation I can come up with. I've also considered
making my own 'Carolina Windom', but from what I've read it doesn't offer me
much improvement. Does it? Might the 'Carolina Windom' approach be a better
idea?

My goal is to keep the replacement costs below $35, which I know I can do
with the doublet or the homebrew 'Carolina Windom'. I'm in no hurry, got all
summer to do this and I am retired. I just want to do what will give me the
best results. I'm looking for opinions, suggestions and practical experience
with using one of these doublet/balun antennas or 'Carolina Windoms' and the
kind of ATU found in most modern transceivers. I don't want the hassle or
expense of an external antenna tuner.

Thanks...and 73's from Cicada humming SW Ohio


--

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

Jim Leder wrote:
This topic has been kicked around so much, I feel like it fits into the
upcoming spring/summer TV reruns. I currently have a G5RV in an inverted Vee
configuration, with the apex at about 35 feet. It works OK on 75/80, pretty
well on 40, OK on 20 and OK on 17. It is a miserable failure everywhere
else. I'm limited in space and height, but after surveying my trees and lot,
I could put up a 135 foot center fed doublet with the apex at about 40 feet
and the ends sloping down to about 15 feet (another inverted Vee, best I can
do with my trees). I would feed it with 450 ohm ladder line to the shack,
mate it with a 4:1 current balun and then connect with a short piece of coax
to my TS450's ATU. Seems like it should work, but I guess I need to ask some
questions:
1) My G5RV is old, and has been patched. I expect it to not survive another
winter or the vinyl eating squirrels. Does the doublet offer me any
improvements? The ladder line would be away from the hungry rodents, free
swinging and not near their trees.
2) Or, should I just rebuild the G5RV and scrape the doublet idea?
3) Is the 4:1 balun a good idea? Seems the only good way to be able to use
the Kenwood's ATU. The G5RV and Kenwood work well together on all bands,
even though it doesn't radiate out of my backyard on some of them.
4) Should I be concerned with RF in the shack with the doublet scenario?
5) Is there a better doublet length than 135 feet? That seems to be the most
common length I see.
6) My intention is to replace the RV with something better, that offers
improved performance on 75/80,40,30,20 and 17. Is it LIKELY this setup will
work, or am I too optimistic? I have an Alpha Delta DXEE which would be
moved to where the G5RV is now, offering me 20,15 and 10 (it's bad on 40).
7) I've spent a bit of time looking over my situation, and this is maybe the
best wire antenna installation I can come up with. I've also considered
making my own 'Carolina Windom', but from what I've read it doesn't offer me
much improvement. Does it? Might the 'Carolina Windom' approach be a better
idea?

My goal is to keep the replacement costs below $35, which I know I can do
with the doublet or the homebrew 'Carolina Windom'. I'm in no hurry, got all
summer to do this and I am retired. I just want to do what will give me the
best results. I'm looking for opinions, suggestions and practical experience
with using one of these doublet/balun antennas or 'Carolina Windoms' and the
kind of ATU found in most modern transceivers. I don't want the hassle or
expense of an external antenna tuner.

If you want to run coax, how about a fan dipole? That seems to me to be
the best of all worlds. Youjust have to spend some (more) time trimming
since the wires interact with each other.

- Mike KB3EIA -

Mike Coslo wrote in message ...
Jim Leder wrote:
This topic has been kicked around so much, I feel like it fits into the
upcoming spring/summer TV reruns. I currently have a G5RV in an inverted Vee
configuration, with the apex at about 35 feet. It works OK on 75/80, pretty
well on 40, OK on 20 and OK on 17. It is a miserable failure everywhere
else. I'm limited in space and height, but after surveying my trees and lot,
I could put up a 135 foot center fed doublet with the apex at about 40 feet
and the ends sloping down to about 15 feet (another inverted Vee, best I can
do with my trees). I would feed it with 450 ohm ladder line to the shack,
mate it with a 4:1 current balun and then connect with a short piece of coax
to my TS450's ATU. Seems like it should work, but I guess I need to ask some
questions:

I don't really recommend that myself. It might work, actually, it
probably would work, but it's hard on that tuner which is not really
made for that type of job.
I would always use a heavier duty outboard tuner if I wanted to run
ladder line.
But thats just me...The tuner in that 450 if fried, costs some hefty
cash flow to fix. It's not made for the real wide impedance variations
you will see with the ladder line fed dipole. It's more of a line
flattener. IE: handy to let you work the whole 80m band, once you are
externally in the ballpark. A 3 or 5 to 1 mismatch is no problem. A 20
or 40 to 1 is gonna hurt it I bet. Will run hot. Might even refuse
some loads, tune, tune, tune, no go, and the tuner will shut off in
disgust. I've seen it happen...


2) Or, should I just rebuild the G5RV and scrape the doublet idea?

Well, maybe not. But I'd find an outboard tuner for the doublet.

3) Is the 4:1 balun a good idea?

Many recommend a 1:1, but the garden variety 4:1 in most tuners that
accept ladder line will work for most matches. I just use the 4:1 in
my tuner if I run ladder line. Not the greatest from a purist point of
view, but I'm not *that* picky....They seem to work for me most all
the time. I always use the min inductance tuning. Very important.

Seems the only good way to be able to use
the Kenwood's ATU. The G5RV and Kenwood work well together on all bands,
even though it doesn't radiate out of my backyard on some of them.

It's no secret I'm not a fan of G5RV's...:/

4) Should I be concerned with RF in the shack with the doublet scenario?

Not really.

5) Is there a better doublet length than 135 feet? That seems to be the most
common length I see.

The best is what fits your bands the best. The best way to find the
best compromises, are to model them. In general, I see the worst
problems on the highest bands, where the dipole is quite long. Using
130 ft 80 m dipoles with ladder line, I've had cases where 10m acted
like a cloud warmer. But the antenna was fairly low to the ground.
Naturally, a half size dipole is bad news also..Lots of tuner loss in
most cases...T net tuners hate half size dipoles...

6) My intention is to replace the RV with something better, that offers
improved performance on 75/80,40,30,20 and 17. Is it LIKELY this setup will
work, or am I too optimistic?

naw. I think it would work pretty well for 80-17....Just get the best,
and biggest tuner you can afford if you do it. You will have lower
losses in general compared to some of the little tuners. IE: I'm using
a MFJ 989c..Not the best in the west, but quite usable for ladder
line, or coax...It has a roller coil, so the inductance setting is
exact. This reduces loss if you are careful tuning.

I have an Alpha Delta DXEE which would be
moved to where the G5RV is now, offering me 20,15 and 10 (it's bad on 40).
7) I've spent a bit of time looking over my situation, and this is maybe the
best wire antenna installation I can come up with. I've also considered
making my own 'Carolina Windom', but from what I've read it doesn't offer me
much improvement. Does it? Might the 'Carolina Windom' approach be a better
idea?

It's no secret I not a fan of windoms or any OCF dipole either...:/
Those are prone to rf in the shack problems if you aren't careful.


My goal is to keep the replacement costs below $35, which I know I can do
with the doublet or the homebrew 'Carolina Windom'. I'm in no hurry, got all
summer to do this and I am retired. I just want to do what will give me the
best results. I'm looking for opinions, suggestions and practical experience
with using one of these doublet/balun antennas or 'Carolina Windoms' and the
kind of ATU found in most modern transceivers. I don't want the hassle or
expense of an external antenna tuner.

If you want to run coax, how about a fan dipole? That seems to me to be
the best of all worlds. You just have to spend some (more) time trimming
since the wires interact with each other.

For under $35, this is by far, the best choice I think. Heck, as far
as I'm concerned, it's the best choice at any price...I run parallel
dipoles on a single coax feed. Very efficient, and no ant band
changing required. Right now, I have 160, 80 and 40. Being I tend to
work less 160 in the summer, I usually convert the 160 dipole to 20m,
by adding insulators at the 16 ft points...I have two other 160
antennas anyway...I use three of them in the winter...The parallel
dipoles will outperform all the other choices on the bands it's
resonant on. And you have a dipole pattern on all those bands. The
only drawback is if you want all bands to 17m, you have to have about
4 dipoles. 80, 40, 20, 17. The 40 dipole will work 15 using the 450
tuner. You probably could work 10m, using that tuner with usable
performance. I doubt the SWR would be over 5 to 1 with the mix of all
the elements. In fact, I think my SWR is pretty low on 10m, even
without a tuner. Same for 6m...Parallel dipoles are easiest to tune if
you spread them apart quite a bit. Don't stack them on top of each
other with spreaders, unless you want a real PIA to tune. Lots of
coupling between the elements if you do that. I place them at right
angles if possible, IE: 80/40 and then the other bands equally in
between those. Always start with the lowest band first, then tune
each higher band. If you have coupling problems it will show up on the
higher band element that is being effected by a lower band element
next to it. You will almost never have a problem on 80m. Only the
higher bands. Sometimes just moving a wire a few feet, can drastically
reduce some coupling you might see. MK

Mark Keith wrote:

Mike Coslo wrote in message ...

Jim Leder wrote:
I could put up a 135 foot center fed doublet with the apex at about 40 feet
and the ends sloping down to about 15 feet (another inverted Vee, best I can
do with my trees). I would feed it with 450 ohm ladder line to the shack,
mate it with a 4:1 current balun and then connect with a short piece of coax
to my TS450's ATU. Seems like it should work, but I guess I need to ask some
questions:

I don't really recommend that myself. It might work, actually, it
probably would work, but it's hard on that tuner which is not really
made for that type of job.

If he's willing to use three different feedline lengths, it will work
like a charm and his ATU will be happy. A 130 ft. dipole is covered on
my web page. Driving the SWR lower than 3:1 by switching the length of
the feedline is a snap and then the ATU is happy, usually over the entire
band. For my 130 ft. dipole fed with "450" ohm ladder-line, a feedline of:

88 ft. works well with my IC-756PRO ATU on 40m, 15m, & 12m.
95 ft. works well with my IC-756PRO ATU on 30m, 17m, & 10m.
105 ft. works well with my IC-756PRO ATU on 20m & 12m.
(Note that the difference in 88 ft. and 105 ft. is 1/2 WL on 12m.)

So with an ATU, three lengths of ladder-line cover all the HF bands
for a 130 ft. dipole. Two 4PDT relays are all that are needed to
switch in three lengths of ladder-line. For 100 watts, two OMRON
LY4's work well.
--
73, Cecil http://www.qsl.net/w5dxp



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