[Elecraft] Elecraft, RJ45 Standard.
Kevin, Thanks for pointing out my typo. I meant 4 pairs. 73 -- Dave Robertson KD1NA __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] elecraft,RJ45 Standard
Folks - due to the large number of posts on this topic, let's end the thread at this time to give our other readers a rest. 73, Eric Moderator /elecraft.com/ On 5/9/2016 3:10 PM, Lynn W. Taylor, WB6UUT wrote: On 5/9/2016 10:03 AM, Jim Brown wrote: At audio levels, the shielding from twisting the wires might be helpful. It is VERY helpful. When I said *might* I was being slightly sarcastic. If a cable has an RJ-45 on each end, there is always a chance in a modern home that the cable is going to carry ethernet or find itself in some other spot that matters. In fact, Murphy is going to see to it that out of all of the cables available, you'll grab that one. 73 -- Lynn __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] elecraft,RJ45 Standard
On 5/9/2016 10:03 AM, Jim Brown wrote: At audio levels, the shielding from twisting the wires might be helpful. It is VERY helpful. When I said *might* I was being slightly sarcastic. If a cable has an RJ-45 on each end, there is always a chance in a modern home that the cable is going to carry ethernet or find itself in some other spot that matters. In fact, Murphy is going to see to it that out of all of the cables available, you'll grab that one. 73 -- Lynn __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] elecraft,RJ45 Standard
On Mon,5/9/2016 1:21 PM, dave wrote: > You're missing the fact that although these conductors INTENTIONALLY > carry DC and low rate signals, they also can PICK UP RF and AF noise. > Twisted pair, when used to carry a signal, is at least as powerful at > rejecting RF and AF noise pickup as coax, but ONLY if the pair is > dedicated to a circuit. And also only if the twisted pair is properly terminated in a balanced termination - on both ends. I was field engineer for Bell. I was sometimes totally amazed at just how good twisted pair are at rejecting noise. As good as coax, if not better. Not true. Yes, cancellation can be improved by balanced termination, but ONLY if balanced broadband -- that is, DC to the highest frequencies of the interference. But twisted pair is VERY effective at rejecting magnetic coupling even when the interface is unbalanced. I learned this from solving a severe RFI problem problem with the serial interface to my K2, way back in 2003. I was using the "official"Elecraft cable, which was parallel conductors, NOT twisted, and my TX antenna was a top-loaded end fed wire with a tuner in the shack for 160 and 80M. At only 12W, coupling to ,my computer via that serial cable caused it to lock up. I replaced that parallel wire cable with CAT5, using one pair per circuit, and making the return connection to the DB9 shells, NOT to the "ground" pin (to solve Pin One Problems). Once I had changed the cable, I could run my Ten Tec Titan to legal limit with no interference up to 17 MHz when I intentionally loaded that same antenna on all the HF bands. If I used shielded twisted pair, I could run full power up through 10M. But . . . the telco pairs are terminated in carefully balanced terminations. I don't think the typical ham/audio install is so carefully designed. They may be, I don't know for sure. I suspect the terminations are, for the most part, unbalanced. There will still be some rejection of noise, maybe a good deal. But not as good as if properly terminated. See my comments above. I have used twisted pair here with good success, but there is some luck involved if the pairs are not properly terminated. I have yet to see a situation where twisted pair made things worse, and it often solves serious RFI issues. In the pro audio world, it is well known, for example, that loudspeaker cables should ALWAYS be twisted pair, NEVER parallel wires (zip cord, glorified or not). Sadly, the high futility folks have never learned that, and most hams haven't either. Audio power amps use feedback around the output stage to reduce distortion, a technique first developed more than 100 years ago (by Bell Labs, I think). RF on the speaker cable will couple via that feedback network to the input of the audio output stage. Replacing the zip cord with twisted pair is an effective fix. Nearly 40 years ago, Prof R. A. Greiner at U of Wis published an AES paper that showed that for all practical purposes, the only thing that matters with loudspeaker cable is DC resistance, and that lower is better. The sole exception was with a VERY rare type of loudspeaker that had a very low impedance at high audio frequencies. The impedance of 99.99% of loudspeakers increases rapidly with increasing frequency. His paper can be found in the Journal of AES in any decent university's technical library. And yes, one of the cables he considered was sold under the Kimber name, which was mfd on the concept of litz wire. :) 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] elecraft,RJ45 Standard
> You're missing the fact that although these conductors INTENTIONALLY > carry DC and low rate signals, they also can PICK UP RF and AF noise. > Twisted pair, when used to carry a signal, is at least as powerful at > rejecting RF and AF noise pickup as coax, but ONLY if the pair is > dedicated to a circuit. And also only if the twisted pair is properly terminated in a balanced termination - on both ends. I was field engineer for Bell. I was sometimes totally amazed at just how good twisted pair are at rejecting noise. As good as coax, if not better. But . . . the telco pairs are terminated in carefully balanced terminations. I don't think the typical ham/audio install is so carefully designed. They may be, I don't know for sure. I suspect the terminations are, for the most part, unbalanced. There will still be some rejection of noise, maybe a good deal. But not as good as if properly terminated. I have used twisted pair here with good success, but there is some luck involved if the pairs are not properly terminated. 73 de dave ab9ca/4 On 5/9/16 12:03 PM, Jim Brown wrote: On Mon,5/9/2016 9:41 AM, Lynn W. Taylor, WB6UUT wrote: If we're talking DC levels, sure, no problem. Low rate signalling just won't matter. You're missing the fact that although these conductors INTENTIONALLY carry DC and low rate signals, they also can PICK UP RF and AF noise. Twisted pair, when used to carry a signal, is at least as powerful at rejecting RF and AF noise pickup as coax, but ONLY if the pair is dedicated to a circuit. That only happens when both ends of the cable are correctly wired. That is, OR and OR/WH will reject noise, but OR and GN will NOT. At audio levels, the shielding from twisting the wires might be helpful. It is VERY helpful. If we're actually using them for Ethernet, then the twisted pairs aren't wires, they're transmission lines. 100 megabit ethernet is running at 100 megahertz. Right. AND -- they are transmission lines at RF frequencies even when the INTENDED signal is AF or even DC. THAT'S HOW they reject RF and AF noise. Wire the cable randomly and you don't have twisted pairs (transmission lines) at VHF frequencies (or above). And you don't have them at AF or HF either. Bottom line -- CAT5 and similar cables are excellent for control wiring and even for RF, but we must ALWAYS wire them so that every circuit uses a pair. Wiring them any other way is a recipe for noise and RFI. 73, Jim K9YC 73 -- Lynn __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] elecraft,RJ45 Standard
On Mon,5/9/2016 9:41 AM, Lynn W. Taylor, WB6UUT wrote: If we're talking DC levels, sure, no problem. Low rate signalling just won't matter. You're missing the fact that although these conductors INTENTIONALLY carry DC and low rate signals, they also can PICK UP RF and AF noise. Twisted pair, when used to carry a signal, is at least as powerful at rejecting RF and AF noise pickup as coax, but ONLY if the pair is dedicated to a circuit. That only happens when both ends of the cable are correctly wired. That is, OR and OR/WH will reject noise, but OR and GN will NOT. At audio levels, the shielding from twisting the wires might be helpful. It is VERY helpful. If we're actually using them for Ethernet, then the twisted pairs aren't wires, they're transmission lines. 100 megabit ethernet is running at 100 megahertz. Right. AND -- they are transmission lines at RF frequencies even when the INTENDED signal is AF or even DC. THAT'S HOW they reject RF and AF noise. Wire the cable randomly and you don't have twisted pairs (transmission lines) at VHF frequencies (or above). And you don't have them at AF or HF either. Bottom line -- CAT5 and similar cables are excellent for control wiring and even for RF, but we must ALWAYS wire them so that every circuit uses a pair. Wiring them any other way is a recipe for noise and RFI. 73, Jim K9YC 73 -- Lynn On 5/9/2016 8:42 AM, David Robertson wrote: As long as you maintain the same standard or a standard you create on BOTH ends of the CAT 5 cable this cable could be used anywhere, regardless of the system used. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] elecraft,RJ45 Standard
Uh, maybe not. If we're talking DC levels, sure, no problem. Low rate signalling just won't matter. At audio levels, the shielding from twisting the wires might be helpful. If we're actually using them for Ethernet, then the twisted pairs aren't wires, they're transmission lines. 100 megabit ethernet is running at 100 megahertz. Wire the cable randomly and you don't have twisted pairs (transmission lines) at VHF frequencies (or above). 73 -- Lynn On 5/9/2016 8:42 AM, David Robertson wrote: As long as you maintain the same standard or a standard you create on BOTH ends of the CAT 5 cable this cable could be used anywhere, regardless of the system used. I understand that maintaining a standard of wire color codes is important for tracing and troubleshooting purposes. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] elecraft,RJ45 Standard
Close. There are 4 pair. On Monday, May 9, 2016 11:42 AM, David Robertson wrote: David Robertson 9:55 AM (1 hour ago) to kenin.stover, Elecraft Kevin, Thanks for the information on the RJ45 standards. what confuses me is there are 6 pair of wires in a CAT 5 cable. In the standards you list, the only difference is the placement of the Orange/Orange-White and Green/Green-White pair of wires. As long as you maintain the same standard or a standard you create on BOTH ends of the CAT 5 cable this cable could be used anywhere, regardless of the system used. I understand that maintaining a standard of wire color codes is important for tracing and troubleshooting purposes. From: Kevin Stover To: elecraft@mailman.qth.net Cc: Date: Mon, 2 May 2016 18:50:46 -0500 Subject: Re: [Elecraft] K3S RJ-45 Pin Alignment The standards go thusly. TIA/EIA 568-A (T568A) Pin 1 - white / green stripe Pin 2 - green Pin 3 - white / orange stripe Pin 4 - blue Pin 5 - white / blue stripe pin 6 - orange pin 7 - white / brown stripe pin 8 - brown TIA/EIA 568-B (T568B) Pin 1 - white / orange stripe Pin 2 - orange Pin 3 - white / green stripe Pin 4 - blue Pin 5 - white / blue stripe Pin 6 - green Pin 7 - white / brown stripe Pin 8 - brown -- Dave Robertson KD1NA __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to wd8...@sbcglobal.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] elecraft,RJ45 Standard
David Robertson 9:55 AM (1 hour ago) to kenin.stover, Elecraft Kevin, Thanks for the information on the RJ45 standards. what confuses me is there are 6 pair of wires in a CAT 5 cable. In the standards you list, the only difference is the placement of the Orange/Orange-White and Green/Green-White pair of wires. As long as you maintain the same standard or a standard you create on BOTH ends of the CAT 5 cable this cable could be used anywhere, regardless of the system used. I understand that maintaining a standard of wire color codes is important for tracing and troubleshooting purposes. From: Kevin Stover To: elecraft@mailman.qth.net Cc: Date: Mon, 2 May 2016 18:50:46 -0500 Subject: Re: [Elecraft] K3S RJ-45 Pin Alignment The standards go thusly. TIA/EIA 568-A (T568A) Pin 1 - white / green stripe Pin 2 - green Pin 3 - white / orange stripe Pin 4 - blue Pin 5 - white / blue stripe pin 6 - orange pin 7 - white / brown stripe pin 8 - brown TIA/EIA 568-B (T568B) Pin 1 - white / orange stripe Pin 2 - orange Pin 3 - white / green stripe Pin 4 - blue Pin 5 - white / blue stripe Pin 6 - green Pin 7 - white / brown stripe Pin 8 - brown -- Dave Robertson KD1NA __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
