Re: [Elecraft] Off topic feedline question

[Bill W4ZV]

Here's a thread on zipcord loss from years ago:

http://elecraft.365791.n2.nabble.com/What-your-mother-didn-t-tell-you-about-transmission-lines-td6780383.html

This is a real world result I observed:

"About 10 years ago ET3PMW was attempting to get on the low bands and only
had zip cord available for transmission line.  I thought it should work fine
for 80 and 160.  However, on 80m running 100 watts he was barely detectible
here using a 1200' Beverage for receive.  Once Paul got some good ladder
line, his signal was typically S8 on 80m and S6 on Topband, where he made
several hundred QSOs with North America even in summer QRN (June/July)."

Stay away from it until you can get decent ladder line!

73,  Bill  W4ZV



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Re: [Elecraft] Off topic feedline question

[Al Scanandoah]

If your main concerns are strength and durability, I'd recommend:
http://trueladderline.com
I've been pleased with the results I've had over the past 15 years.
Al, K2ZN


Sent via mobile
 Original message From: Michael Blake <k9...@mac.com> Date: 
11/7/17  11:12 AM  (GMT-05:00) To: Elecraft Mailing List 
<elecraft@mailman.qth.net> Subject: Re: [Elecraft] Off topic feedline question 
Thanks to all of you for your responses.  My need for a lower impedance 
parallel line is not so much a matter of loss but to minimize the impedance 
transformer effect a 25’ window line (400 ohm) has when terminated in a low 
impedance load.  My real concern was for the ability of the line to survive in 
weather and sunlight and its RF voltage breakdown rating.

The two data references were quite helpful.  Thanks again!

Michael Blake
k9...@mac.com

From: Michael Blake
Sent: Tuesday, November 7, 2017 9:12 AM
To: Elecraft Mailing List
Subject: [Elecraft] Off topic feedline question

My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and terminates 
in a 1:1 balun which is then connected to a remote autotuner via 24 inches of 
9913F.

The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC 
insulated "speaker" wire.  The impedance would be quite low, probably in the 90 
ohm range, and world certainly handle the applied power (500 watts) but I have 
not been able find any information regarding RF loss.

Michael Blake
k9...@mac.com
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Re: [Elecraft] Off topic feedline question

[Wes Stewart]

You are mistaken. 25' of ladderline is only about a tenth of a wavelength and 
does not invert impedance. I suggest you download Dan's TLDetails program: 
http://ac6la.com/tldetails1.html and play with it.  Put in what you think, or 
have measured, the feedpoint Z is then select one of the Wireman ladderlines and 
see what happens as you change the length.


You may find some data on zip cord as feeders, but I would avoid them like the 
plague, particularly as you are trying to solve a problem that doesn't exist.


Wes  N7WS


On 11/7/2017 7:08 AM, Michael Blake wrote:
My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and 
terminates in a 1:1 balun which is then connected to a remote autotuner via 24 
inches of 9913F.


The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC 
insulated "speaker" wire.  The impedance would be quite low, probably in the 
90 ohm range, and world certainly handle the applied power (500 watts) but I 
have not been able find any information regarding RF loss.


Michael Blake
k9...@mac.com 


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Re: [Elecraft] Off topic feedline question

[Wes Stewart]

I'm sending this again because I didn't see it come through:

You are mistaken. 25' of ladderline is only about a tenth of a wavelength and 
does not invert impedance. I suggest you download Dan's TLDetails program: 
http://ac6la.com/tldetails1.html and play with it.  Put in what you think, or 
have measured, the feedpoint Z is then select one of the Wireman ladderlines and 
see what happens as you change the length.


You may find some data on zip cord as feeders, but I would avoid them like the 
plague, particularly as you are trying to solve a problem that doesn't exist.


Wes  N7WS


On 11/7/2017 9:12 AM, Michael Blake wrote:

Thanks to all of you for your responses.  My need for a lower impedance 
parallel line is not so much a matter of loss but to minimize the impedance 
transformer effect a 25’ window line (400 ohm) has when terminated in a low 
impedance load.  My real concern was for the ability of the line to survive in 
weather and sunlight and its RF voltage breakdown rating.

The two data references were quite helpful.  Thanks again!

Michael Blake
k9...@mac.com

From: Michael Blake
Sent: Tuesday, November 7, 2017 9:12 AM
To: Elecraft Mailing List
Subject: [Elecraft] Off topic feedline question

My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and terminates 
in a 1:1 balun which is then connected to a remote autotuner via 24 inches of 
9913F.

The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC insulated 
"speaker" wire.  The impedance would be quite low, probably in the 90 ohm 
range, and world certainly handle the applied power (500 watts) but I have not been able 
find any information regarding RF loss.

Michael Blake
k9...@mac.com
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Re: [Elecraft] Off topic feedline question

[Michael Blake]

Thanks to all of you for your responses.  My need for a lower impedance 
parallel line is not so much a matter of loss but to minimize the impedance 
transformer effect a 25’ window line (400 ohm) has when terminated in a low 
impedance load.  My real concern was for the ability of the line to survive in 
weather and sunlight and its RF voltage breakdown rating.

The two data references were quite helpful.  Thanks again!

Michael Blake
k9...@mac.com

From: Michael Blake
Sent: Tuesday, November 7, 2017 9:12 AM
To: Elecraft Mailing List
Subject: [Elecraft] Off topic feedline question

My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and terminates 
in a 1:1 balun which is then connected to a remote autotuner via 24 inches of 
9913F.

The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC 
insulated "speaker" wire.  The impedance would be quite low, probably in the 90 
ohm range, and world certainly handle the applied power (500 watts) but I have 
not been able find any information regarding RF loss.

Michael Blake
k9...@mac.com
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Re: [Elecraft] Off topic feedline question

[Robert Cunnings]

Yes, googling "zip cord hf loss" yields the classic QST article:

http://www.w1npp.org/events/2010/2010-f~1/antennas/wire/790303~1.PDF

among others. Here are measurements made with a Rigexpert AA-600;

http://owenduffy.net/blog/?p=327

Bob NW8L

On Tue, 7 Nov 2017, Michael Blake wrote:


The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC 
insulated "speaker" wire.  The impedance would be quite low, probably in the 
90 ohm range, and world certainly handle the applied power (500 watts) but I 
have not been able find any information regarding RF loss.


Michael Blake
k9...@mac.com__
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Re: [Elecraft] Off topic feedline question

[David Kuechenmeister]

I didn't study this site too deeply, but KP4MD has the most appropriate 
characteristics on her page, here, http://www.qsl.net/kp4md/zipcord.htm.
You might also look at Owen Duffy's pages. His transmission line calculator is 
great. I think the last entry for zip 105 is zip cord, but you should email him 
and ask. The page is at http://owenduffy.net/calc/tl/tllc.php
vy 73,Dave N4KD 

On Tuesday, November 7, 2017 9:12 AM, Michael Blake  wrote:
 

 My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and terminates 
in a 1:1 balun which is then connected to a remote autotuner via 24 inches of 
9913F.

The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC 
insulated "speaker" wire.  The impedance would be quite low, probably in the 90 
ohm range, and world certainly handle the applied power (500 watts) but I have 
not been able find any information regarding RF loss.

Michael Blake
k9...@mac.com
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[Elecraft] Off topic feedline question

[Michael Blake]

My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and terminates 
in a 1:1 balun which is then connected to a remote autotuner via 24 inches of 
9913F.

The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC insulated 
"speaker" wire.  The impedance would be quite low, probably in the 90 ohm 
range, and world certainly handle the applied power (500 watts) but I have not been able 
find any information regarding RF loss.

Michael Blake
k9...@mac.com
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