Re: [Elecraft] BNCs
On Sun,10/12/2014 6:32 PM, Acbross via Elecraft wrote: Don't know where anyone got the idea that BNCs made for RG-8x we 75 ohm. I worked in the tv industry for many years and we used hundreds of BNCs that were made specifically for 75 ohm video. By the way, RG-59 not RG-79. While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. 75 ohm connectors were important with analog video because of the smearing of very fine detail in a high res image, and because studios do lots of patching and routing. 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] BNCs
Thanks Jim I was going to ask that exact question. For the amateur world, does it make a difference if a 75 ohm connector is installed on a 50 ohm feedline. You made it very clear for everyone. Thanks! Mike va3mw On Mon, Oct 13, 2014 at 12:15 PM, Jim Brown j...@audiosystemsgroup.com wrote: On Sun,10/12/2014 6:32 PM, Acbross via Elecraft wrote: Don't know where anyone got the idea that BNCs made for RG-8x we 75 ohm. I worked in the tv industry for many years and we used hundreds of BNCs that were made specifically for 75 ohm video. By the way, RG-59 not RG-79. While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. 75 ohm connectors were important with analog video because of the smearing of very fine detail in a high res image, and because studios do lots of patching and routing. 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 va...@portcredit.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
Re: [Elecraft] BNCs
Jim, It may not make a difference to performance on HF but it does matter because the centre pins have different diameters of solder pot / crimp barrel to match the cable impedance used. Also incorrectly mated connectors risk damage to their centre connectors by forcing the engagement. Use the correct connector for the cable in use. 73 Peter G3SMT On 13/10/2014 16:15, Jim Brown wrote: On Sun,10/12/2014 6:32 PM, Acbross via Elecraft wrote: Don't know where anyone got the idea that BNCs made for RG-8x we 75 ohm. I worked in the tv industry for many years and we used hundreds of BNCs that were made specifically for 75 ohm video. By the way, RG-59 not RG-79. While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. 75 ohm connectors were important with analog video because of the smearing of very fine detail in a high res image, and because studios do lots of patching and routing. 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 peter.to...@talktalk.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
Re: [Elecraft] BNCs
Peter The larger concern is that most of us have no way of being able to tell the difference from a 50 ohm bnc to a 75 ohm bnc. We buy these online and at flee markets, which is part of the reality. Is there an easy way to tell them apart? I assume the same is also true for N connectors which are essentially a BNC but with a different casing. Mike va3mw On Mon, Oct 13, 2014 at 12:30 PM, Peter Torry peter.to...@talktalk.net wrote: Jim, It may not make a difference to performance on HF but it does matter because the centre pins have different diameters of solder pot / crimp barrel to match the cable impedance used. Also incorrectly mated connectors risk damage to their centre connectors by forcing the engagement. Use the correct connector for the cable in use. 73 Peter G3SMT On 13/10/2014 16:15, Jim Brown wrote: On Sun,10/12/2014 6:32 PM, Acbross via Elecraft wrote: Don't know where anyone got the idea that BNCs made for RG-8x we 75 ohm. I worked in the tv industry for many years and we used hundreds of BNCs that were made specifically for 75 ohm video. By the way, RG-59 not RG-79. While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. 75 ohm connectors were important with analog video because of the smearing of very fine detail in a high res image, and because studios do lots of patching and routing. 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 peter.to...@talktalk.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 va...@portcredit.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
Re: [Elecraft] BNCs
On Mon,10/13/2014 9:30 AM, Peter Torry wrote: It may not make a difference to performance on HF but it does matter because the centre pins have different diameters of solder pot / crimp barrel to match the cable impedance used. What matters is that the connector match the physical dimensions of the cable so that it can be properly installed, and this is true regardless of impedance. Also incorrectly mated connectors risk damage to their centre connectors by forcing the engagement. Use the correct connector for the cable in use. Zo depends upon o.d. of the center conductor with the connectors mated, and would be established by the o.d. of the female pin receptacle, not the o.d. of the male tip. Although I have not studied the mechanical Standard for 75 ohm BNCs, I would VERY surprised if the dimensions of a proper 75 ohm connector would prevent it from mating with a proper 50 ohm connector. Have you studied such a spec? I'm quite active in international Standards work (with the AES) and that sort of incompatibility is something we make certain to avoid! 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] BNCs
On Mon 13 Oct Jim Brown wrote: the o.d. of the male tip. Although I have not studied the mechanical Standard for 75 ohm BNCs, I would VERY surprised if the dimensions of a proper 75 ohm connector would prevent it from mating with a proper 50 ohm connector. Have you studied such a spec? I'm quite active in international Standards work (with the AES) and that sort of incompatibility is something we make certain to avoid! It's certainly possible, given a 75 Ohm male connector and a 50 Ohn female connector, to end up without good electrical contact on the central conductor, especially if you're dealing with cheap plugs and sockets. Been there, suffered the consequences. -- 73, Rick, M0LEP (KX3 #3281) __ 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] BNCs
YES The 75 ohm series are UG-260/U connectors, the 50 ohm series is the UG-88/U. If they don't have this stamped into the rear barrel of the connector, THEY ARE Counterfeits or JUST PLAIN TRASH! There is a lot of crap parts available at hamfests these days! Be careful what you buy!! 73, Sandy W5TVW On 10/13/2014 11:18 AM, Michael Walker wrote: Thanks Jim I was going to ask that exact question. For the amateur world, does it make a difference if a 75 ohm connector is installed on a 50 ohm feedline. You made it very clear for everyone. Thanks! Mike va3mw On Mon, Oct 13, 2014 at 12:15 PM, Jim Brown j...@audiosystemsgroup.com wrote: On Sun,10/12/2014 6:32 PM, Acbross via Elecraft wrote: Don't know where anyone got the idea that BNCs made for RG-8x we 75 ohm. I worked in the tv industry for many years and we used hundreds of BNCs that were made specifically for 75 ohm video. By the way, RG-59 not RG-79. While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. 75 ohm connectors were important with analog video because of the smearing of very fine detail in a high res image, and because studios do lots of patching and routing. 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 va...@portcredit.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 ebj...@charter.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
Re: [Elecraft] BNCs
The big difference of the 75 and 50 ohm connectors is the fit of the connectors to the coax size, NOT the center pin size which is the same. BNC connectors are really NOT constant impedance especially at VHF/UHF frequencies like proper N series connectors are. This makes no difference impedance wise on HF gear. I guess this is also why no one has standardized on a better connector for the HF frequency range instead of the PL-259/SO-239impedance bumps! 73, Sandy W5TVW On 10/12/2014 8:32 PM, Acbross via Elecraft wrote: Don't know where anyone got the idea that BNCs made for RG-8x we 75 ohm. I worked in the tv industry for many years and we used hundreds of BNCs that were made specifically for 75 ohm video. By the way, RG-59 not RG-79. Now days I build hundreds of cables for RF out of rg-58 and rg-8x BNCs and they use 50 ohm connectors not 75 ohm connectors. Remember that the impedance of coax is based on the ratio of the center conductor to the outer conductor and if you compare the 75 ohm connector you will see that the center pin is much smaller in diameter. Anyone need 200 silver plated 75 ohm BNCs? Art KC7GF Rf Stuff.com __ 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 ebj...@charter.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
Re: [Elecraft] BNCs
On Mon,10/13/2014 10:34 AM, Rick M0LEP wrote: especially if you're dealing with cheap plugs and sockets. From my work on the AES Standards Committee Working Group on Connectors, I can tell you that junk and even counterfeit connectors are the problem, not the nominal Zo. Junk connectors of any sort are a constant source of problems. Only a fool buys anything but name brand connectors. This applies to ALL connector types -- UHF, BNC, RCA, DIN, XLR, 1/8-in, 1/4-in. For UHF, this means Amphenol. For XLR, RCA, 1/8-in, and 1/4-in this means Switchcraft and Neutrik. For DIN, that means Switchcraft and Preh. I don't work enough with BNCs to know the good mfrs. 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] BNCs
Jim - Good quality BNC connectors can be had from Amphenol and AMP. I normally use AMP crimp-type connectors for BNC applications, have _never_ had one fail, and I purchase them by the hundreds. Takes only a few seconds to install one. One other good supplier of RF connectors is Kings. It has been a few years since I had to buy any, so I am assuming these suppliers still exist. Having the correct tools to install these connectors is not a luxury, and yes, they are expensive. Here again, you tend to get what you pay for. And you are correct, money spent on a good quality connector is never wasted. On the other hand, money spent on a cheap connector is almost always wasted. - Jim, KL7CC On 10/13/2014 10:03 AM, Jim Brown wrote: On Mon,10/13/2014 10:34 AM, Rick M0LEP wrote: especially if you're dealing with cheap plugs and sockets. From my work on the AES Standards Committee Working Group on Connectors, I can tell you that junk and even counterfeit connectors are the problem, not the nominal Zo. Junk connectors of any sort are a constant source of problems. Only a fool buys anything but name brand connectors. This applies to ALL connector types -- UHF, BNC, RCA, DIN, XLR, 1/8-in, 1/4-in. For UHF, this means Amphenol. For XLR, RCA, 1/8-in, and 1/4-in this means Switchcraft and Neutrik. For DIN, that means Switchcraft and Preh. I don't work enough with BNCs to know the good mfrs. 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 jwi...@gci.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
Re: [Elecraft] BNCs
While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. I disagree ... *DO NOT MIX 75 and 50 Ohm connectors*. 50 Ohm male connectors will split the center contact of a 75 Ohm female wile 75 Ohm male connectors will not make reliable connection with the center contact of a 50 Ohm female. In general, a 75 Ohm center pin will not accept the center conductor of 50 Ohm cable and a 50 Ohm center pin can not be *reliably* attached (either crimp or solder) to the smaller center conductor of 75 Ohm cable due to the relative sizes. 73, ... Joe, W4TV On 2014-10-13 12:15 PM, Jim Brown wrote: On Sun,10/12/2014 6:32 PM, Acbross via Elecraft wrote: Don't know where anyone got the idea that BNCs made for RG-8x we 75 ohm. I worked in the tv industry for many years and we used hundreds of BNCs that were made specifically for 75 ohm video. By the way, RG-59 not RG-79. While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. 75 ohm connectors were important with analog video because of the smearing of very fine detail in a high res image, and because studios do lots of patching and routing. 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 li...@subich.com __ 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] BNCs
Although I have not studied the mechanical Standard for 75 ohm BNCs, I would VERY surprised if the dimensions of a proper 75 ohm connector would prevent it from mating with a proper 50 ohm connector. Have you studied such a spec? Yes, I have used both in the TV stations - 50 Ohm for RF systems and 75 for video systems. The center pin (male) and contact (female) *ARE DIFFERENT SIZE*. Forcing a 50 Ohm connector into a 75 Ohm socket will split the center contact while putting a 75 Ohm connector into a 50 Ohm socket will result in insufficient tension on the center pin (and unreliable contact). 73, ... Joe, W4TV On 2014-10-13 12:45 PM, Jim Brown wrote: On Mon,10/13/2014 9:30 AM, Peter Torry wrote: It may not make a difference to performance on HF but it does matter because the centre pins have different diameters of solder pot / crimp barrel to match the cable impedance used. What matters is that the connector match the physical dimensions of the cable so that it can be properly installed, and this is true regardless of impedance. Also incorrectly mated connectors risk damage to their centre connectors by forcing the engagement. Use the correct connector for the cable in use. Zo depends upon o.d. of the center conductor with the connectors mated, and would be established by the o.d. of the female pin receptacle, not the o.d. of the male tip. Although I have not studied the mechanical Standard for 75 ohm BNCs, I would VERY surprised if the dimensions of a proper 75 ohm connector would prevent it from mating with a proper 50 ohm connector. Have you studied such a spec? I'm quite active in international Standards work (with the AES) and that sort of incompatibility is something we make certain to avoid! 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 li...@subich.com __ 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] BNCs
According to the specs in the RF Industires catalog, pages 7 and 14 in the version I have here, the center pins of 50 ohm and 75 ohm BNC's are indeed the same size: .053 +/-.001 inch. The difference is Zo is generated by using dielectric in the 50 ohm but none in the 75 ohm, and slight difference in the inside dimensions of the plus and sockets. It is a little hard to tell from the drawings whether or not you can plug a 50 into 75, and vise versa, with no issues. Although the pins are the same size, there is a slight difference in the inside diameters and the depths of the two fittings are different. This is complicated by the fact that the 50 and 75 ohm fittings use different reference planes to make the measurements. The catalog is available on the RF Industries web site. 73 de dave ab9ca/4 On 10/13/14 1:32 PM, Joe Subich, W4TV wrote: While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. I disagree ... *DO NOT MIX 75 and 50 Ohm connectors*. 50 Ohm male connectors will split the center contact of a 75 Ohm female wile 75 Ohm male connectors will not make reliable connection with the center contact of a 50 Ohm female. In general, a 75 Ohm center pin will not accept the center conductor of 50 Ohm cable and a 50 Ohm center pin can not be *reliably* attached (either crimp or solder) to the smaller center conductor of 75 Ohm cable due to the relative sizes. 73, ... Joe, W4TV On 2014-10-13 12:15 PM, Jim Brown wrote: On Sun,10/12/2014 6:32 PM, Acbross via Elecraft wrote: Don't know where anyone got the idea that BNCs made for RG-8x we 75 ohm. I worked in the tv industry for many years and we used hundreds of BNCs that were made specifically for 75 ohm video. By the way, RG-59 not RG-79. While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. 75 ohm connectors were important with analog video because of the smearing of very fine detail in a high res image, and because studios do lots of patching and routing. 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 li...@subich.com __ 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 ho13d...@gmail.com . __ 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] BNCs
According to the specs in the RF Industries catalog, pages 7 and 14 in the version I have here, the center pins of 50 ohm and 75 ohm BNC's are indeed the same size: .053 +/-.001 inch. The difference is Zo is generated by using dielectric in the 50 ohm but none in the 75 ohm, and slight difference in the inside dimensions of the plugs and sockets. It is a little hard to tell from the drawings whether or not you can plug a 50 into 75, and vise versa, with no issues. Although the pins are the same size, there is a slight difference in the inside diameters and the depths of the two fittings are different. This is complicated by the fact that the 50 and 75 ohm fittings use different reference planes to make the measurements. The catalog is available on the RF Industries web site. 73 de dave ab9ca/4 On 10/13/14 1:32 PM, Joe Subich, W4TV wrote: While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. I disagree ... *DO NOT MIX 75 and 50 Ohm connectors*. 50 Ohm male connectors will split the center contact of a 75 Ohm female wile 75 Ohm male connectors will not make reliable connection with the center contact of a 50 Ohm female. In general, a 75 Ohm center pin will not accept the center conductor of 50 Ohm cable and a 50 Ohm center pin can not be *reliably* attached (either crimp or solder) to the smaller center conductor of 75 Ohm cable due to the relative sizes. 73, ... Joe, W4TV On 2014-10-13 12:15 PM, Jim Brown wrote: On Sun,10/12/2014 6:32 PM, Acbross via Elecraft wrote: Don't know where anyone got the idea that BNCs made for RG-8x we 75 ohm. I worked in the tv industry for many years and we used hundreds of BNCs that were made specifically for 75 ohm video. By the way, RG-59 not RG-79. While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. 75 ohm connectors were important with analog video because of the smearing of very fine detail in a high res image, and because studios do lots of patching and routing. 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 li...@subich.com __ 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 ho13d...@gmail.com . __ 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] BNCs
Hello Jim, I quite agree that what matters is that the connector match the physical dimensions of the cable. Originally they didn't mate, 50 Ohm was 50 Ohm and 75 was 75.The pins were different diameters, and there were warranty warnings to only use the correct connectors with equipment such as the old Tek 475 scope. A 50 Ohm plug would damage a 75 Ohm socket. Now modern BNC connectors don't quite make their correct impedance characteristics but will physically mate with each other without mechanical issue if made to IEC 169-8. The electrical characteristics vary between the different impedances and one should be wary of the 93 R variety. I understand in the US MIL-STD 348B is similar but doesn't state the Zo.Then we have the far eastern manufacturers that appear to be slightly different again. All in all a bit of a nightmare so that was why I suggested being careful in selection and using branded connectors from a reputable manufacturer. On the Elecraft front my Def Spec connector doesn't mate correctly with the BNC socket on the rear panel of the K3. I think I had better retire to a dark room. 73 PeterG3SMT On 13/10/2014 16:45, Jim Brown wrote: On Mon,10/13/2014 9:30 AM, Peter Torry wrote: It may not make a difference to performance on HF but it does matter because the centre pins have different diameters of solder pot / crimp barrel to match the cable impedance used. What matters is that the connector match the physical dimensions of the cable so that it can be properly installed, and this is true regardless of impedance. Also incorrectly mated connectors risk damage to their centre connectors by forcing the engagement. Use the correct connector for the cable in use. Zo depends upon o.d. of the center conductor with the connectors mated, and would be established by the o.d. of the female pin receptacle, not the o.d. of the male tip. Although I have not studied the mechanical Standard for 75 ohm BNCs, I would VERY surprised if the dimensions of a proper 75 ohm connector would prevent it from mating with a proper 50 ohm connector. Have you studied such a spec? I'm quite active in international Standards work (with the AES) and that sort of incompatibility is something we make certain to avoid! 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] BNCs
All, And while the pin/receptacle dimensions are important to maintain physical integrity, the characteristic impedance doesn't come into play unless you experience a considerable phase length such as a 30 degree discontinuity at a given frequency. So at HF the phase length of the 70-50 Ω discontinuity experienced by a BNC connector (or any other impedance) is very short. Important at UHF, yes, important at HF, nope. Myron WVØH Printed on Recycled Data On Oct 13, 2014, at 12:36 PM, Joe Subich, W4TV li...@subich.com wrote: and unreliable contact). __ 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] BNCs
On 10/13/2014 10:42 AM, Sandy Blaize wrote: There is a lot of crap parts available at hamfests these days! Be careful what you buy!! Had cable problems with P3 when I first got it. Bob, K6XX, at Elecraft and who I know well called me and said [only slightly tongue-in-cheek] they'd send me a replacement cable ... *if* I promised to cut the old one in small pieces and bury it at the bottom of our trash can so it never could appear at a ham swap. :-) I did. If you want connectors that fit, and that work all the time, you'll need to totally avoid the cheap stuff. I use only Amphenol coax connectors. 73, Fred K6DGW - Northern California Contest Club - CU in the 2015 Cal QSO Party 3-4 Oct 2015 - www.cqp.org __ 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] BNCs
The practical answer is try to insert your coax into the bushing. RG-59 and RG8X are the same size and RG-58 is smaller. If RG-58 is sloppy in the bushing and RG-59 or RG8X fits then it is OK to use unless you are trying to get an exact match for micro-wave. If you are a micro-wave engineer you are more qualified than I, but for 6 meters and below the extremely small bump will not be noticeable. You are jousting windmills to avoid an impedence bump that you cannot see. Willis 'Cookie' Cooke, TDXS DX Chairman K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart On Monday, October 13, 2014 12:42 PM, Sandy Blaize ebj...@charter.net wrote: YES The 75 ohm series are UG-260/U connectors, the 50 ohm series is the UG-88/U. If they don't have this stamped into the rear barrel of the connector, THEY ARE Counterfeits or JUST PLAIN TRASH! There is a lot of crap parts available at hamfests these days! Be careful what you buy!! 73, Sandy W5TVW On 10/13/2014 11:18 AM, Michael Walker wrote: Thanks Jim I was going to ask that exact question. For the amateur world, does it make a difference if a 75 ohm connector is installed on a 50 ohm feedline. You made it very clear for everyone. Thanks! Mike va3mw On Mon, Oct 13, 2014 at 12:15 PM, Jim Brown j...@audiosystemsgroup.com wrote: On Sun,10/12/2014 6:32 PM, Acbross via Elecraft wrote: Don't know where anyone got the idea that BNCs made for RG-8x we 75 ohm. I worked in the tv industry for many years and we used hundreds of BNCs that were made specifically for 75 ohm video. By the way, RG-59 not RG-79. While you are entirely correct that there are 75 ohm and 50 ohm BNCs, the difference DOES NOT MATTER at HF, because the connector is such a small fraction of a wavelength and the difference is small. 75 ohm connectors were important with analog video because of the smearing of very fine detail in a high res image, and because studios do lots of patching and routing. 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 va...@portcredit.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 ebj...@charter.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 wrco...@yahoo.com __ 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] BNCs Enough!
Without sounding my horn too loudly I have servered on IEEE connector committees and been paid big bucks to solve the production line problems. Counterfet connectors is too mild a term. There is some real crap out there and your eyeballs won't be able to detect it. Things like finish and and spring tention problems can not be seen. I recall one particular connector that was causing a 2db measured loss over a prefered Kings or Amphenol connector. The imported brand X connector was available in both 50 and 75 ohm versions, both of which were unmarked. When actually measured with a TDR they both measured 62 ohms. Folks, life is too short to mess with S T U F F like this. Do you really have to touch the wet paint or believe the sign. 73, Fred, AE6QL -Original Message- From: Fred Jensen k6...@foothill.net Sent: Oct 13, 2014 12:49 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] BNCs On 10/13/2014 10:42 AM, Sandy Blaize wrote: There is a lot of crap parts available at hamfests these days! Be careful what you buy!! Had cable problems with P3 when I first got it. Bob, K6XX, at Elecraft and who I know well called me and said [only slightly tongue-in-cheek] they'd send me a replacement cable ... *if* I promised to cut the old one in small pieces and bury it at the bottom of our trash can so it never could appear at a ham swap. :-) I did. If you want connectors that fit, and that work all the time, you'll need to totally avoid the cheap stuff. I use only Amphenol coax connectors. 73, Fred K6DGW - Northern California Contest Club - CU in the 2015 Cal QSO Party 3-4 Oct 2015 - www.cqp.org __ 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 fptowns...@earthlink.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
Re: [Elecraft] BNCs Enough!
For what it might be worth, I only use 7/16 DIN connectors for my jumpers and transmission lines. When I have coax switches and baluns made, as well as accessories such as power meters, I always order them with 7/16 DINs. I also always buy either Andrew or Times Microwave connectors depending whether I am using hard line or coax such as LMR600 or LMR900. It costs a bunch more, but the 7/16 DIN connectors can't be beat. Alan/KD7GC Alan R. Downing Phoenix, AZ From: Fred Townsend-2 [via Elecraft] [mailto:ml-node+s365791n7593827...@n2.nabble.com] Sent: Monday, October 13, 2014 2:52 PM To: kd7gc Subject: Re: BNCs Enough! Without sounding my horn too loudly I have servered on IEEE connector committees and been paid big bucks to solve the production line problems. Counterfet connectors is too mild a term. There is some real crap out there and your eyeballs won't be able to detect it. Things like finish and and spring tention problems can not be seen. I recall one particular connector that was causing a 2db measured loss over a prefered Kings or Amphenol connector. The imported brand X connector was available in both 50 and 75 ohm versions, both of which were unmarked. When actually measured with a TDR they both measured 62 ohms. Folks, life is too short to mess with S T U F F like this. Do you really have to touch the wet paint or believe the sign. 73, Fred, AE6QL -Original Message- From: Fred Jensen [hidden email] Sent: Oct 13, 2014 12:49 PM To: [hidden email] Subject: Re: [Elecraft] BNCs On 10/13/2014 10:42 AM, Sandy Blaize wrote: There is a lot of crap parts available at hamfests these days! Be careful what you buy!! Had cable problems with P3 when I first got it. Bob, K6XX, at Elecraft and who I know well called me and said [only slightly tongue-in-cheek] they'd send me a replacement cable ... *if* I promised to cut the old one in small pieces and bury it at the bottom of our trash can so it never could appear at a ham swap. :-) I did. If you want connectors that fit, and that work all the time, you'll need to totally avoid the cheap stuff. I use only Amphenol coax connectors. 73, Fred K6DGW - Northern California Contest Club - CU in the 2015 Cal QSO Party 3-4 Oct 2015 - www.cqp.org __ 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] _ If you reply to this email, your message will be added to the discussion below: http://elecraft.365791.n2.nabble.com/Re-BNCs-Enough-tp7593827.html To unsubscribe from Elecraft, click here http://elecraft.365791.n2.nabble.com/template/NamlServlet.jtp?macro=unsubsc ribe_by_codenode=365791code=a2Q3Z2NAcS5jb218MzY1NzkxfDE3MzQ0NDk4ODY= . http://elecraft.365791.n2.nabble.com/template/NamlServlet.jtp?macro=macro_v iewerid=instant_html%21nabble%3Aemail.namlbase=nabble.naml.namespaces.Basi cNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template .NodeNamespacebreadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_ emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml NAML -- View this message in context: http://elecraft.365791.n2.nabble.com/Re-BNCs-Enough-tp7593827p7593832.html Sent from the Elecraft mailing list archive at Nabble.com. __ 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
