OT Wet 450 ohm ladder line

15 messages

OT Wet 450 ohm ladder line

Reply Threaded

Sorry for an off-topic question. Does anyone have any information about the
dry vs wet characteristics of "450 ohm" ladder line? I have never used this
type of line, but I might have to use it for "mechanical" reasons to feed
another antenna now being built. I am told that its characteristics change
when wet from rain, but which characteristics change and by how much at HF.
A remote ATU to compensate is not to be used with this particular antenna /
feeder.

Any comment would be appreciated.

73,

Geoff
GM4ESD

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Bob Cunnings

Re: OT Wet 450 ohm ladder line

Reply Threaded

N7WS took a look at precisely this subject:

http://users.triconet.org/wesandlinda/ladder_line.pdf

BTW I use 450 ohm ladder line here to feed a c.f. vertical wire
doublet for multi-band operation using a balanced tuner - at least
when dry, it's the best option to keep loss low and for mechanical
reasons too.

Bob NW8L

On Tue, Mar 17, 2009 at 8:04 AM, Geoffrey Mackenzie-Kennedy
<[hidden email]> wrote:

> Sorry for an off-topic question. Does anyone have any information about the
> dry vs wet characteristics of "450 ohm" ladder line? I have never used this
> type of line, but I might have to use it for "mechanical" reasons to feed
> another antenna now being built. I am told that its characteristics change
> when wet from rain, but which characteristics change and by how much at HF.
> A remote ATU to compensate is not to be used with this particular antenna /
> feeder.
>
> Any comment would be appreciated.
>
> 73,
>
> Geoff
> GM4ESD
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

w2bvh

Re: OT Wet 450 ohm ladder line

Reply Threaded

In reply to this post by Geoffrey Mackenzie-Kennedy

I find the antenna system loses a *lot* of its effectiveness when the
ladder line is wet. As a guess I'd say a half or more of the received
signal strength is lost (and , I suppose, similarly for transmit) when
the line is wet..

When not wet its a very effective component in my antenna system. I've
been using a 131' center fed Zepp with ladder line and Cecil Moore's
(W5DXP) "non-tuner" for about 10 years and am very pleased with the
results. See http://www.w5dxp.com/notuner.htm for details.

73,
Lenny W2BVH

Geoffrey Mackenzie-Kennedy wrote:

P.B. Christensen

Re: OT Wet 450 ohm ladder line

Reply Threaded

>I find the antenna system loses a *lot* of its effectiveness when the
> ladder line is wet.

IMO, construction of open-feeder line is worth the effort. I am using an
old stash of E.F. Johnson spreader insulators, but effective balanced line
can be made by using PVC tubing, with the ends sliced to insert soft copper
wire.

> When not wet its a very effective component in my antenna system. I've
> been using a 131' center fed Zepp with ladder line and Cecil Moore's
> (W5DXP) "non-tuner" for about 10 years and am very pleased with the
> results. See http://www.w5dxp.com/notuner.htm for details.

And my vote for the best "all purpose" HF antenna of all time. Nearly an
entire book on transmission line theory and antenna radiation behavior can
be learned just by understanding the mechanics of the W5DXP antenna.

Paul, W9AC

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Wes Stewart

Re: OT Wet 450 ohm ladder line

Reply Threaded

In reply to this post by Bob Cunnings

Indeed I did. However, a few more words. The experiments that I ran were by necessity somewhat contrived and weren't very repeatable. What I was attempting to show was that there can be a detrimental effect when these lines become moist. Roy Lewallen, W7EL, has also written about this.

The paper was a result of my reading "The Lure of the Ladder Line" (ref 1 in the paper) and saying to myself, "Self, this looks too good to be true." When something looks this way, it usually is.

Something mentioned, but discussed at much greater length in correspondence with Dean Straw, was the total lack of concern about balun and tuner losses at that time. I showed him by example that the ever popular tee-network used in many tuners that has three adjustable elements can be misadjusted so that it provides a match to the source but has extraordinarily high insertion loss. There are in effect an infinite number of wrong combinations and one that is correct.

It wasn't long after this correspondence that articles by Frank Witt appeared on evaluating antenna tuners and today it is almost routine to see mention of tuner losses and possible misadjustment in papers on the subject. Whether this is coincidental or not is left to the reader.

But when I see threads about, for example 43-foot verticals being "matched" on 160-meters with a built-in tuner or a little automatic box at the base of the antenna, or recommendations to use ladder line to feed ground-mounted verticals I really have to bite my tongue.

Wes N7WS

--- On Tue, 3/17/09, Bob Cunnings <[hidden email]> wrote:

> From: Bob Cunnings <[hidden email]>
> Subject: Re: [Elecraft] OT Wet 450 ohm ladder line
> To: "Elecraft Discussion List" <[hidden email]>
> Date: Tuesday, March 17, 2009, 8:35 AM
> N7WS took a look at precisely this subject:
>
> http://users.triconet.org/wesandlinda/ladder_line.pdf
>
> BTW I use 450 ohm ladder line here to feed a c.f. vertical
> wire
> doublet for multi-band operation using a balanced tuner -
> at least
> when dry, it's the best option to keep loss low and for
> mechanical
> reasons too.
>
> Bob NW8L
>
>
>
> On Tue, Mar 17, 2009 at 8:04 AM, Geoffrey Mackenzie-Kennedy
> <[hidden email]> wrote:
> > Sorry for an off-topic question. Does anyone have any
> information about the
> > dry vs wet characteristics of "450 ohm"
> ladder line? I have never used this
> > type of line, but I might have to use it for
> "mechanical" reasons to feed
> > another antenna now being built. I am told that its
> characteristics change
> > when wet from rain, but which characteristics change
> and by how much at HF.
> > A remote ATU to compensate is not to be used with this
> particular antenna /
> > feeder.
> >
> > Any comment would be appreciated.
> >
> > 73,
> >
> > Geoff
> > GM4ESD
> >
> >
> ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list:
> http://www.qsl.net/donate.html
> >
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> http://www.qsl.net/donate.html

Monty Shultes

Re: OT Wet 450 ohm ladder line

Reply Threaded

In reply to this post by w2bvh

I use open wire feeder for my center-fed antenna. It is #14 wire separated
by plastic 4-inch spacers. It is effective and does not lose much, if
anything, when wet.
Monty K2DLJ

> I find the antenna system loses a *lot* of its effectiveness when the
> ladder line is wet. As a guess I'd say a half or more of the received
> signal strength is lost (and , I suppose, similarly for transmit) when
> the line is wet..
>
> When not wet its a very effective component in my antenna system. I've
> been using a 131' center fed Zepp with ladder line and Cecil Moore's
> (W5DXP) "non-tuner" for about 10 years and am very pleased with the
> results. See http://www.w5dxp.com/notuner.htm for details.
>
> 73,
> Lenny W2BVH
>
>
> Geoffrey Mackenzie-Kennedy wrote:
>>
>> Geoff
>> GM4ESD

Ron D'Eau Claire

Re: OT Wet 450 ohm ladder line

Reply Threaded

In reply to this post by Geoffrey Mackenzie-Kennedy

Open wire line changes a bit in wet weather due to moisture on the
insulation between the wires. The worst is the type with a continuous web of
insulation that was commonly used for television lead-in before coax came
into common use. Next best is "window" line what is the same basic
insulation, but wider spacing (and a higher impedance) with openings -
windows - cut in the insulation to make it more like "air" dielectric line.
The best is true open wire line which seems to be what you are referring to.
With good insulators, it is virtually unaffected by moisture unless you dunk
it in salt water. I've used both the commercial type with (polystyrene?)
insulators and home brew stuff I made up using ceramic insulators.

At my last QTH I had an "inverted V" doublet fed with open wire line. The
center support was a wooden pole, so I made up the feed line using common
"dog bone" end insulators. The insulators were mounted on the support pole
using screw-eye standoffs. I got a bunch of the cheap screw eyes with the
little insulator in the center made for use with TV "twinlead" and popped
the little insulator out. The eye is soft metal that is easily bent, so I
opened it up to slip it around the center of each 'dog bone' insulator then
clamped it down with pliers. Ribs on the insulator kept the eye centered.
Screwed them into the pole at about 3 foot intervals and then strung some
#14 copper wire through the ends to make up the feeder. Kept the wire under
a little tension with a few small ty-wraps to secure it. A bit of wire
wrapped around the main conductor and running outside the hole would so as
well. With a white pole, white "dog bone" insulators and using white
insulated wire, the whole installation was very tidy and the feeder
virtually invisible.

I never noticed any significant change in tuning requirements (used an
external manual tuner) on any band when it was dry, in the middle of a
typical Oregon "gully-washer" downpour or when it was coated in ice.

Ron AC7AC

-----Original Message-----
Sorry for an off-topic question. Does anyone have any information about the
dry vs wet characteristics of "450 ohm" ladder line? I have never used this
type of line, but I might have to use it for "mechanical" reasons to feed
another antenna now being built. I am told that its characteristics change
when wet from rain, but which characteristics change and by how much at HF.
A remote ATU to compensate is not to be used with this particular antenna /
feeder.

Any comment would be appreciated.

73,

Geoff
GM4ESD

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Phil and Christina

Re: OT Wet 450 ohm ladder line

Reply Threaded

In reply to this post by Monty Shultes

I have had good results with the W7FG (SK) open wire line. It is well made
and performs well. If you want a true open wire line that is already made
up, give this a try. It is sold today through www.trueladderline.com. I
have no affiliation with this company; I just like the feed line.

73,

Phil, NS7P

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of Monty Shultes
Sent: Tuesday, March 17, 2009 8:14 AM
To: w2bvh; [hidden email]; [hidden email]
Subject: Re: [Elecraft] OT Wet 450 ohm ladder line

I use open wire feeder for my center-fed antenna. It is #14 wire separated
by plastic 4-inch spacers. It is effective and does not lose much, if
anything, when wet.
Monty K2DLJ

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Vic K2VCO

Re: OT Wet 450 ohm ladder line

Reply Threaded

In reply to this post by Geoffrey Mackenzie-Kennedy

Geoffrey Mackenzie-Kennedy wrote:
> Sorry for an off-topic question. Does anyone have any information about the
> dry vs wet characteristics of "450 ohm" ladder line? I have never used this
> type of line, but I might have to use it for "mechanical" reasons to feed
> another antenna now being built. I am told that its characteristics change
> when wet from rain, but which characteristics change and by how much at HF.
> A remote ATU to compensate is not to be used with this particular antenna /
> feeder.

I don't have the quantitative data that Geoff wants, but my experience was that when
feeding a 40-meter dipole with the stuff, the tuning changed significantly when it rained.
I don't know what actually accounts for this. Some people have suggested that waxing the
line reduces the effect.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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Geoffrey Mackenzie-Kennedy

Re: OT Wet 450 ohm ladder line

Reply Threaded

In reply to this post by Wes Stewart

Many thanks for all the comments about wet "450 ohm" ladder line.

There is no doubt in my mind about open wire line being the better choice,
and I would normally use it. But in this particular application there is the
risk of open wire line being damaged by or ensnarled in a fairly dense
growth of small trees while hoisting the antenna. The feeder run is about
300ft between the antenna and my remote antenna select switch box.

Further thought required.

73,

Geoff
GM4ESD

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Steve Ellington

Re: OT Wet 450 ohm ladder line

Reply Threaded

I don't see why you couldn't chop out about 50 or 75% of those webs. That
should reduce the loss considerably when wet. Minor discontinuities at HF
should be insignificant and feeder Z for multiband use is irrelevant.
N4LQ
Steve Ellington
[hidden email]
----- Original Message -----
From: "Geoffrey Mackenzie-Kennedy" <[hidden email]>
To: "Elecraft Discussion List" <[hidden email]>
Sent: Tuesday, March 17, 2009 12:23 PM
Subject: Re: [Elecraft] OT Wet 450 ohm ladder line

> Many thanks for all the comments about wet "450 ohm" ladder line.
>
> There is no doubt in my mind about open wire line being the better choice,
> and I would normally use it. But in this particular application there is
> the
> risk of open wire line being damaged by or ensnarled in a fairly dense
> growth of small trees while hoisting the antenna. The feeder run is about
> 300ft between the antenna and my remote antenna select switch box.
>
> Further thought required.
>
> 73,
>
> Geoff
> GM4ESD
>
>
>
>
>
>
>
>
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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Eric Swartz - WA6HHQ, Elecraft

Re: OT Wet 450 ohm ladder line [END of Thread]

Reply Threaded

Let's let this thread rest for now. :-)

73, Eric WA6HHQ
Elecraft List Moderator

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Jim Brown-10

Re: OT Wet 450 ohm ladder line

Reply Threaded

In reply to this post by Wes Stewart

On Tue, 17 Mar 2009 08:13:12 -0700 (PDT), Wes Stewart wrote:

>Indeed I did. However, a few more words. The experiments that I
>ran were by necessity somewhat contrived and weren't very
>repeatable. What I was attempting to show was that there can be a
>detrimental effect when these lines become moist. Roy Lewallen,
>W7EL, has also written about this.

IMO, Wes is being rather modest. His work on what happens with window
line when it gets wet (greatly increased loss) was published by ARRL
in the Antenna Compendium Vol 6. That book also includes two
excellent papers by Frank Witt. All three are "required reading," and
well worth the price of the book ($23).

73,

Jim Brown K9YC

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David Y.

Re: OT Wet 450 ohm ladder line

Reply Threaded

In reply to this post by P.B. Christensen

----- Original Message -----
From: "Paul Christensen" <[hidden email]>
To: "Elecraft Discussion List" <[hidden email]>
Sent: Tuesday, March 17, 2009 8:12 AM
Subject: Re: [Elecraft] OT Wet 450 ohm ladder line

> And my vote for the best "all purpose" HF antenna of all
> time. Nearly an
> entire book on transmission line theory and antenna
> radiation behavior can
> be learned just by understanding the mechanics of the
> W5DXP antenna.
>
> Paul, W9AC

Back when Cecil was still W6RCA, and living here in Arizona,
many of us got to see his rather ingenious arrangement first
hand. I think it may have been at Ft. Tuthill. And a
picture was worth a thousand words, as it sounded more
complicated than it really was if he just described it to
you verbally. The trick was to adjust the length of the
feedline to eliminate any stray RF problems, which can
frequently occur on one band or another when using balanced
line. Cecil's system works like a charm, and is really
worth looking into if you want to multi-band with a minimum
of oddball issues.

Dave W7AQK

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Ignacy

Re: OT Wet 450 ohm ladder line [END of Thread]

Reply Threaded

In reply to this post by Eric Swartz - WA6HHQ, Elecraft

Sorry for ignoring the recommendation but I could not resist.

The measurements are on 6m. Assuming that we use a ladderline-fed dipole up to 30m (a beam for 20m up), the feeder is nearly vertical so that most of the water runs down, and a KW (not on 10MHz) vaporizes some of the water, there may be no problem at all.

Ignacy

Eric Swartz - WA6HHQ, Elecraft wrote:

Let's let this thread rest for now. :-)

73, Eric WA6HHQ
Elecraft List Moderator

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