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 -