Submitted by Anonymous on Fri, 09/11/1998 - 04:50 Forums: LML Archive From: Angier M. Ames <alphadog [at] nii.net> Subject: Re: Coax cable selection Date: Fri, 11 Sep 1998 00:50:15 -0400 To: <lancair.list [at] olsusa.com> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> I'm sure this subject has been disected ad nauseum in this list previously...but either I missed it or forgot (due to my age of course). Wouldn't it be great if there was a simple, black and white answer. I'm sitting here with half a dozen technical data sheets from Belden Wire and Cable Company on RG 58/U (9223), RG 58/U (8240),RG 58C/U, RG 58A/U, RG 142 (83242) and RG 142 (84142) and it looks like they make excellent bathroom reading material...my eyelids are already beginning to droop. Is there any compelling reason why I should not go to my local Radio Shack store and buy x number of feet of Tandy RG58 cable and then move on to the next project? Post a Reply Coax cable selection Submitted by Anonymous on Fri, 09/11/1998 - 08:29 From: John Cooper <heyduke [at] digital.net> Subject: Re: Coax cable selection Date: Fri, 11 Sep 1998 04:29:04 -0400 To: <lancair.list [at] olsusa.com> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> The main difference between brands/types of coax is the signal loss at a given frequency. I think you would find the Radio Shack variety more lossy than the Belden. Does this matter? Probably not much on a 15' run from your com radio back to the antenna in the tail. However, remember that the signal that is "lost" is radiated through the shield of the coax into the airplane environment. This can cause other problems besides weak signal strength. For instance, the fuel level sender in my friends L-235 picks up stray radiation this way which causes his fuel gage to peg every time he keys his mic. Me? I went with mil-spec RG-142 for my com feed, and the Radio Shack stuff for the marker beacon coax. I plan to use the "good" RG-58 to connect to the nav antenna which is in the baggage compartment ceiling (when I get around to installing a nav radio, someday). I will also use the lowest-loss coax I can find for the transponder feed. I'd use RG-8 if it weren't for the adapters I'd need on each end. Check out http://www.aeroelectric.com reply Coax cable selection Submitted by Anonymous on Fri, 09/11/1998 - 16:51 From: Bill Gradwohl <Bill [at] YCC.COM> Subject: Re: Coax cable selection Date: Fri, 11 Sep 1998 11:51:28 -0500 To: <lancair.list [at] olsusa.com> Content-Disposition: inline X-Mailing-List: lancair.list [at] olsusa.com <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> One of the things to consider with coax is how will you terminate the ends. The choice of termination method also determines the type of coax to get to begin with. We've installed thousands of coax network connections over the years as networking consultants, and the best method of termination is either a soldered or crimped on connector. By best, I mean reliable, low noise, and likely to last a long time. Almost no one is willing to solder on a connector however. That leaves the crimped on variety as the best option. The screw on types are terrible. They corrode over time, and we've seen serious networking problems due to the connectors. Their physical properties are also not very good. The connectors are easily pulled off the cable with minimal effort. We've also seen that many people damage the coax in the process of trying to put on the screw on connectors. The crimp on connectors effectively squeeze the connector onto the coax. This means that the coax had better offer enough physical resistance to get a good crimp. Some coax cables have a hollow plastic core with a plastic spiral keeping the center conductor centered within the coax. The hollow part is easily compressed by the crimp process, and therefore does not produce a quality end product. The coax may be electrically good, the connector may be good, but the combination doesn't work very well. Other types of coax have a relatively soft foam core that surrounds the center conductor. This is better, but still not what you want. The best coax has a hard plastic core that is difficult to deform. When a crimp tool wraps a connector on that type of coax, it's there to stay. We've tried to rip the connectors off these cables and usually can't do it. We have also found that plenum rated coax is physically tougher and just slightly smaller in diameter than regular PVC jacketed coax. Coax with a plenum rating is usually Teflon coated, and will not give off poison gas if it burns. One last point. If you can see a deformation in the coax where it was kinked during the installation process, consider it a bad cable and replace it. Coax should be installed so as to produce bends with a minimum bend radius of 6 inches. If you kink the cable as is likely to happen if it is unspooled improperly, it will radiate your signal at the kink and less at your antenna. Bill Gradwohl IV-P N858B reply Post a Reply You must have JavaScript enabled to use this form. Your name Subject Comment * Switch to plain text editorMore information about text formats Text format Filtered HTMLPlain text Filtered HTMLWeb page addresses and e-mail addresses turn into links automatically.Each email address will be obfuscated in a human readable fashion or, if JavaScript is enabled, replaced with a spam resistent clickable link. Email addresses will get the default web form unless specified. If replacement text (a persons name) is required a webform is also required. Separate each part with the "|" pipe symbol. 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Coax cable selection Submitted by Anonymous on Fri, 09/11/1998 - 08:29 From: John Cooper <heyduke [at] digital.net> Subject: Re: Coax cable selection Date: Fri, 11 Sep 1998 04:29:04 -0400 To: <lancair.list [at] olsusa.com> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> The main difference between brands/types of coax is the signal loss at a given frequency. I think you would find the Radio Shack variety more lossy than the Belden. Does this matter? Probably not much on a 15' run from your com radio back to the antenna in the tail. However, remember that the signal that is "lost" is radiated through the shield of the coax into the airplane environment. This can cause other problems besides weak signal strength. For instance, the fuel level sender in my friends L-235 picks up stray radiation this way which causes his fuel gage to peg every time he keys his mic. Me? I went with mil-spec RG-142 for my com feed, and the Radio Shack stuff for the marker beacon coax. I plan to use the "good" RG-58 to connect to the nav antenna which is in the baggage compartment ceiling (when I get around to installing a nav radio, someday). I will also use the lowest-loss coax I can find for the transponder feed. I'd use RG-8 if it weren't for the adapters I'd need on each end. Check out http://www.aeroelectric.com reply
Coax cable selection Submitted by Anonymous on Fri, 09/11/1998 - 16:51 From: Bill Gradwohl <Bill [at] YCC.COM> Subject: Re: Coax cable selection Date: Fri, 11 Sep 1998 11:51:28 -0500 To: <lancair.list [at] olsusa.com> Content-Disposition: inline X-Mailing-List: lancair.list [at] olsusa.com <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> One of the things to consider with coax is how will you terminate the ends. The choice of termination method also determines the type of coax to get to begin with. We've installed thousands of coax network connections over the years as networking consultants, and the best method of termination is either a soldered or crimped on connector. By best, I mean reliable, low noise, and likely to last a long time. Almost no one is willing to solder on a connector however. That leaves the crimped on variety as the best option. The screw on types are terrible. They corrode over time, and we've seen serious networking problems due to the connectors. Their physical properties are also not very good. The connectors are easily pulled off the cable with minimal effort. We've also seen that many people damage the coax in the process of trying to put on the screw on connectors. The crimp on connectors effectively squeeze the connector onto the coax. This means that the coax had better offer enough physical resistance to get a good crimp. Some coax cables have a hollow plastic core with a plastic spiral keeping the center conductor centered within the coax. The hollow part is easily compressed by the crimp process, and therefore does not produce a quality end product. The coax may be electrically good, the connector may be good, but the combination doesn't work very well. Other types of coax have a relatively soft foam core that surrounds the center conductor. This is better, but still not what you want. The best coax has a hard plastic core that is difficult to deform. When a crimp tool wraps a connector on that type of coax, it's there to stay. We've tried to rip the connectors off these cables and usually can't do it. We have also found that plenum rated coax is physically tougher and just slightly smaller in diameter than regular PVC jacketed coax. Coax with a plenum rating is usually Teflon coated, and will not give off poison gas if it burns. One last point. If you can see a deformation in the coax where it was kinked during the installation process, consider it a bad cable and replace it. Coax should be installed so as to produce bends with a minimum bend radius of 6 inches. If you kink the cable as is likely to happen if it is unspooled improperly, it will radiate your signal at the kink and less at your antenna. Bill Gradwohl IV-P N858B reply
Coax cable selection
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Coax cable selection
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