On Tue, 07 Dec 2004 10:29:10 -0700, Wes Stewart
wrote:

"As an aside, I regret including so much about the wet condition. I
tried to make it clear that this was really worst case and not
something that would be seen in practice, but there has been so much
negative commentary about it, that it detracts from the point I was
trying to make."

Actually, Wes you left out a very important consideration for those of
us living is damp areas.... Moss!

Danny, K6MHE

On Tue, 07 Dec 2004 09:55:21 -0800, Dan Richardson
wrote:

|On Tue, 07 Dec 2004 10:29:10 -0700, Wes Stewart
|wrote:
|
|"As an aside, I regret including so much about the wet condition. I
|tried to make it clear that this was really worst case and not
|something that would be seen in practice, but there has been so much
|negative commentary about it, that it detracts from the point I was
|trying to make."
|
|Actually, Wes you left out a very important consideration for those of
|us living is damp areas.... Moss!

Yes, I remember.

For those that are interested, Danny lives amongst the Redwoods on the
N. California coast and he sent me a length of window line that he had
taken down that was covered in moss.

I had hoped to get set up to measure it but the 10% RH in Tucson
conspired to kill the stuff.

Nevertheless, I suspect that it was no longer a low-loss line but a
high-moss line instead.

Wes Stewart wrote:
On Mon, 06 Dec 2004 22:00:24 -0500, Mike Coslo
wrote:

|Cecil Moore wrote:
|
| Roy Lewallen wrote:
|
| My measurements, posted on this newsgroup some time ago and also
| published in QST's Technical Correspondence even longer ago, were for
| 300 ohm TV twinlead. The line was not lying on a wooden deck, nor did
| the measurements involve detergent of any kind.
|
|
| Who was it who published loss data based on laying the ladder-line
| on a wooden deck and/or squirting a wetting agent on it? Did you
| use a wetting agent?
|
| The N7WS experiment was accomplished by coating the line with a wetting
|agent.

No, the line wasn't "coated" with a wetting agent, a drop of
Microclean was added to a spray bottle of deionized water.

Wetting agent is as wetting agent does. You don't need much, but its
effects are dramatic.


|
| The wire was suspended horizontally, 12 feet of it.
|
| The author notes that it was "difficult to maintain uniform wetness"
|during the time it took to run the experiment. This would mean that he
|likely pooled water on the line.

No, I never said that either.


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

Is my source.


The quoted text:

The reason for lower accuracy of we measurements is that it was
difficult to maintain uniform "wetness" during the several seconds it
took to make the measurements. Nevertheless, this lack of control is not
much different than the actual conditions a line might encounter in the
field.

end quote.


I'm assuming that you tried to maintain uniform wetness, hence the
judgment that it was difficult to do so.


For greater accuracy, 201
point-by-point measurements were made over the frequency range. This
takes some time, during which the moisture layer moved around (i.e.
was not uniform). This had the effect of corrupting the data
somewhat.

|
| And finally, I performed a little experiment. I have the ladder line
|from that antenna that was up for 2 years. Application of some water
|showed that it would bead up very nicely.

Bring your line out here to Arizona and leave it in the sun for two
years and re-run your experiment.



No, on second thought, don't come out here. There are too damn many
people moving here already and polluting the air with plasticizers.
At least Cecil left and went back to Texas.

|
| I just don't think the test conditions are very realistic. But it does
|tell me not to wash my ladder line with soap and water! ;^)

I stated, "The results of this are probably worse case and not
something that would necessarily be encountered in a typical
installation."

Also, if you would look at my "update" on my web site, you would see
the following:

"As an aside, I regret including so much about the wet condition. I
tried to make it clear that this was really worst case and not
something that would be seen in practice, but there has been so much
negative commentary about it, that it detracts from the point I was
trying to make."

I'll add you and Cecil to my list.

Gee Wes, I'm not trying to make a big argument with you! The experiment
was well conducted. But I do disagree with the initial assumptions. I
think wetting agent on a horizontally placed line is indeed worst case,
but it is a worst case that is not likely to ever happen in real life.
As you pretty much note.


And you are welcome to visit us here in beautiful Central PA any time
you like! 8^)

- Mike KB3EIA -

I once decided to try 300 ohm twinlead on my inverted Vee. I picked up
the cheapest stuff I could get from Radio Scrap and dropped it from the
vertex at about 50' down into the shack. It worked so well that it stayed
up for thirteen years.

I never cleaned it, and it went through all kinds of weather including
rain, freezing rain, snow, and at times was coated with hoarfrost. I never
noticed any degradation due to rain or snow.

I didn't do any measurements on it, and perhaps tweaked the tuner once
in a while, but in my opinion it was the best antenna I ever had (discounting
beams, mag loops, and verticals).

It went up in 83 and came down in 96 -- clean as a whistle, and was cut into
j-poles and other smaller antennas.

Anecdotal perhaps, for what it's worth...

Irv VE6BP

I still have a bit of it in my shop waiting for some future requirement.

--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/index.html
Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/index.htm
Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/index.htm
--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

Most people wouldn't notice if a few dB of loss come and go, unless it's
very abrupt. (And even then, it might not be noticed except under
unusual or very low-signal conditions.) Ionospheric conditions cause
much greater changes. Unless we have a solid reference antenna for
comparison, there's no way most of us would ever know if a few dB of
loss was coming and going. And, most people wouldn't care anyway.

When we pigeonhole antennas into the binary categories of "works" and
"doesn't work", there's a lot of room for slop in where the dividing
line is drawn.

Roy Lewallen, W7EL

Irv Finkleman wrote:
I once decided to try 300 ohm twinlead on my inverted Vee. I picked up
the cheapest stuff I could get from Radio Scrap and dropped it from the
vertex at about 50' down into the shack. It worked so well that it stayed
up for thirteen years.

I never cleaned it, and it went through all kinds of weather including
rain, freezing rain, snow, and at times was coated with hoarfrost. I never
noticed any degradation due to rain or snow.

I didn't do any measurements on it, and perhaps tweaked the tuner once
in a while, but in my opinion it was the best antenna I ever had (discounting
beams, mag loops, and verticals).

It went up in 83 and came down in 96 -- clean as a whistle, and was cut into
j-poles and other smaller antennas.

Anecdotal perhaps, for what it's worth...

Irv VE6BP

I still have a bit of it in my shop waiting for some future requirement.

On Tue, 07 Dec 2004 16:23:58 -0500, Mike Coslo
wrote:

[snip]

| | The author notes that it was "difficult to maintain uniform wetness"
| |during the time it took to run the experiment. This would mean that he
| |likely pooled water on the line.
|
| No, I never said that either.
|
|
|http://users.triconet.org/wesandlinda/ladder_line.pdf
|
|Is my source.

I'm familiar with that source.
|
|
|The quoted text:
|
|The reason for lower accuracy of we measurements is that it was
|difficult to maintain uniform "wetness" during the several seconds it
|took to make the measurements. Nevertheless, this lack of control is not
|much different than the actual conditions a line might encounter in the
|field.
|
|end quote.
|
|
| I'm assuming that you tried to maintain uniform wetness, hence the
|judgment that it was difficult to do so.

As I said previously (below), "uniform" in this case meant "unchanging
during the measurement". With an A/C duct blowing dry air on the
sample, it was difficult to do.
|
|
| For greater accuracy, 201
| point-by-point measurements were made over the frequency range. This
| takes some time, during which the moisture layer moved around (i.e.
| was not uniform). This had the effect of corrupting the data
| somewhat.
|
| | I just don't think the test conditions are very realistic. But it does
| |tell me not to wash my ladder line with soap and water! ;^)

I guess I fail to understand what "realistic" conditions should apply.
Should I have taken a $250K analyzer out to your back yard or Cecil's?
[g]

The situation was thus:

I had a day job, trying to keep AMRAAM, TOW and Tomahawk missiles
flying. If I and the equipment weren't otherwise tied up, I could
make a few "personal" measurements.

I didn't measure only one sample, but five different lines, including
the open wire control.

The measurements were made in a 16' x 20' shielded room with an 8'
ceiling. This, the equipment placement and the need to access both
ends of the lines, unfortunately limited the length of the samples and
other factors dictated the frequency range that was usable.

The lines had to be taut, since the open wire line had no spacers
other than at the ends.

Horizontal seemed logical since any other orientation brought the ends
closer to the metal walls of the room or allowed the open-wire
conductors to sag toward each other.

I started with no, zip, nada, zero "initial assumptions", other than
the stated belief that hams tend to think that these lines are
lossless in almost any application and that I could make decent
measurements and find out. I had no ax to grind. I personally don't
use window or open-wire lines, preferring Heliax and resonant antennas
instead.

Wetting the lines was almost an afterthought. I remembered Roy's
Technical Correspondence on the issue and other anecdotal reports and
thought I would take a quick look. (With Roy's permission, I will put
a .pdf of this on my site)

|
| I stated, "The results of this are probably worse case and not
| something that would necessarily be encountered in a typical
| installation."
|
| Also, if you would look at my "update" on my web site, you would see
| the following:
|
| "As an aside, I regret including so much about the wet condition. I
| tried to make it clear that this was really worst case and not
| something that would be seen in practice, but there has been so much
| negative commentary about it, that it detracts from the point I was
| trying to make."
|
| I'll add you and Cecil to my list.
|
| Gee Wes, I'm not trying to make a big argument with you! The experiment
|was well conducted. But I do disagree with the initial assumptions. I
|think wetting agent on a horizontally placed line is indeed worst case,
|but it is a worst case that is not likely to ever happen in real life.
|As you pretty much note.

Yeah, pretty much.

| And you are welcome to visit us here in beautiful Central PA any time
|you like! 8^)

Thanks but I spent a week in PA once going to a corona measurement
course. Flew all day on Easter Sunday to get there and when I got
settled into the hotel I was greated by and experienced my first
earthquake. I don't know whether to come back or not. [g]

Roy Lewallen wrote:

Most people wouldn't notice if a few dB of loss come and go, unless it's
very abrupt. (And even then, it might not be noticed except under
unusual or very low-signal conditions.) Ionospheric conditions cause
much greater changes. Unless we have a solid reference antenna for
comparison, there's no way most of us would ever know if a few dB of
loss was coming and going. And, most people wouldn't care anyway.

When we pigeonhole antennas into the binary categories of "works" and
"doesn't work", there's a lot of room for slop in where the dividing
line is drawn.

Roy Lewallen, W7EL

I agree Roy. I'm the stick it up in the air and if I work lots of stations
and hear things most of the other local stations can't then I'm a happy camper.

I'll settle for all the space between 'works' and 'doesn't work' -- much
less stress and lots more fun. I guess thats why they say 'Ignorance is
Bliss' or 'What they don't know won't hurt them'

73

--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/index.html
Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/index.htm
Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/index.htm
--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

The problem is that the "works" threshold is different for every person
and every situation. A lot of people seem to believe that what "works"
for one person and situation will "work" for them for their own
particular situation. Simply accepting that is much easier than
thinking, but then we've all been conditioned to be satisfied with
solutions to complex problems in the form of 30 second sound bites.

What I try to do is explain the relative merits of one approach or
another, in a quantitative way when possible, so those one or two people
out there willing to spend a few minutes of thought can decide for
themselves how to best trade things off -- whether one method or another
is more likely to "work" for them. I know this isn't a popular approach
in today's instant-gratification world -- thanks to those sound bites,
any response that isn't grossly oversimplistic has forever been dubbed
"waffling".

Roy Lewallen, W7EL

Irv Finkleman wrote:

I agree Roy. I'm the stick it up in the air and if I work lots of stations
and hear things most of the other local stations can't then I'm a happy camper.

I'll settle for all the space between 'works' and 'doesn't work' -- much
less stress and lots more fun. I guess thats why they say 'Ignorance is
Bliss' or 'What they don't know won't hurt them'

73

On Tue, 07 Dec 2004 13:40:13 -0700, Wes Stewart wrote:

I had hoped to get set up to measure it but the 10% RH in Tucson
conspired to kill the stuff.

Nevertheless, I suspect that it was no longer a low-loss line but a
high-moss line instead.


I could send you a few samples large enough to fit a dielectrometer.

OTOH, I don't experience nearly as much static electricity up here as I
did in the desert.

--
Bob Nielsen, N7XY n7xy (at) n7xy.net
Bainbridge Island, WA http://www.n7xy.net

Edmund H. Ramm wrote:
In "Cecil Moore" writes:


[...]
I have never seen rain make more than a two foot change necessary


With true open wire line the neccesary "change" would be 0 feet.


and the SWR only ever changed by about 0.2.


Falsified by the also increased losses.


[...]
I am savvy enough not to have a horizontal run of ladder-line out
in the rain. :-)



In due time the dirt which comes down with the rain will also stick
to a vertical run of twinlead, thereby gradually obviating an initally
acceptable performance.


Two years and my twinlead still sheds water like a duck.

At least in my case, the short time that I have been a Ham, I have seen
more problem with water in coax than I have seen water problems with
twinlead.

But we knew about those problems because the antenna didn't lose a bit
of signal. It simply quit working at all!

- Mike KB3EIA -