Off topic feedline question
Locked
 
|
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 [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Off topic feedline question
|
|
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 > [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
|
|
In reply to this post by Michael Blake
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 <[hidden email]> 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 [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Off topic feedline question
|
|
In reply to this post by Michael Blake
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 > [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Off topic feedline question
|
|
In reply to this post by 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 [hidden email] 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 [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Off topic feedline question
|
|
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 > [hidden email] > > 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 > [hidden email] > ______________________________________________________________ > 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 > Message delivered to [hidden email] > > ______________________________________________________________ > 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 > Message delivered to [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Off topic feedline question
|
|
In reply to this post by Michael Blake
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 <[hidden email]> Date: 11/7/17 11:12 AM (GMT-05:00) To: Elecraft Mailing List <[hidden email]> 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 [hidden email] 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 [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
|
|
In reply to this post by Michael Blake
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 -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ 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 Message delivered to [hidden email] |
«
Return to Elecraft
|
1 view|%1 views
| Free forum by Nabble | Edit this page |