Coaxial cable RG142 RG400 LMR400 confusion. - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: July 14, 2019, 05:23:24 am
content: I am reading about coaxial cable, stranding and shielding. I have stumbled upon the RG142 cable that has a solid core and the RG400 that should be about the same but with stranded core. Now have I also fund the LMR400, I have always thought that RG and LMR was about the same but to my surprise the LMR400 is with solid core like the RG142 and not at all like the RG400 stranded core. While trying to find out more about the LMR / RG I did also find the LMR400 flexible that again contained multi core!What are the differance, LMR / RG?what is most flexible?

author: tautech
author_rank: Super Contributor
timestamp: July 14, 2019, 05:43:29 am
content: Coax_Cable_Specification_Chart.pdf(23.38 kB - downloaded 2161 times.)

author: FriedMule
author_rank: Frequent Contributor
timestamp: July 14, 2019, 09:48:08 am
content: Quote from: tautech on July 14, 2019, 05:43:29 amThank you, it looks like the RG400 is an whole other beast! And maybe the most flexible?

author: David Hess
author_rank: Super Contributor
timestamp: July 14, 2019, 05:47:03 pm
content: LMR cables are generally improved replacements for RG cables but they are not the same.I really like RF-142 and RG-400 for patch cables because their double shielding makes them very tough and the Teflon dielectric makes them easy to solder.

author: FriedMule
author_rank: Frequent Contributor
timestamp: July 14, 2019, 06:18:35 pm
content: Quote from: David Hess on July 14, 2019, 05:47:03 pmThanks, I think of you in high regards and what you say is without any doubt from my side! When that is said, I have to look a bit confused, and please ask you where I am reading wrong in the above link? To me it did look like the RG400 was fare superior then the other.The reason for me to choose "the best cable" is to avoid common noob errors and to shield against all the noise I have in my room, refrigiator, cheap SMPS, flickering lights and so on. On the other hand do I want to use the RG400 as standard workhorse cables between my gear, so it is maybe not to great if the cable is a stiff piece of iron or thick like a garden hose. :-)

author: David Hess
author_rank: Super Contributor
timestamp: July 14, 2019, 07:23:45 pm
content: Quote from: FriedMule on July 14, 2019, 06:18:35 pmNoise usually gets into sensitive circuits through means other than coaxial cable, but double shielding is necessary in certain applications. For instance when testing receiver sensitivity, the test signal tends to leak out of the patch cable attached to the source directly into the receiver bypassing any attenuation stages; double shielded cable helps considerably with this.I like RG-400 because it is more flexible than RG-142, the double shielding makes it more mechanically rugged at the connectors, the Teflon dielectric makes it easy to solder, and the solid Teflon dielectric makes it resistant to contamination which would affect loss. In practice however, RG-142 is just as good and a little easier to work with except for being stiffer. I have had troubles in the past with plain RG-58 and especially RG-8X cables failing or becoming high loss.RG-316 is the Teflon version of 0.1 inch diameter RG-174 so also very useful when you need to solder coaxial cable directly into your circuit but need something thinner. It is not double shielded but I have some RG-316 patch cables for their extra flexibility.LMR cables use a braid over aluminum foil shield so are really only suitable for fixed applications where flexing is minimized.