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Can coax cable be spliced? If so, what is the correct method? Will splicing coax result in a db loss or change impedence? |
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I can't imagine a good method for splicing coax without a coupler. Radio shack has this kit for RG-6 http://www.radioshack.com/product/index.jsp?productId=2062638 I did a quick search for LMR-400 couplers and didn't find anything, but I only spent a few minutes looking. |
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Nick, Yes coaxial cable could be spliced but I would personally not recommended doing it. The spliced section would no longer have a correct characteristic impedance as designed. The design formula for characteristic impedance of a single coaxial line is: Zo = 138/The square root of E x log10 x D/d Zo = Characteristice Impedance E = Dielectric constant (air is 1, Cellular Polyethylene is 1.5, Solid Polyethylene is 2.3, TFE Teflon is 2.0) D = Inside diameter of the "return" (outer) conductor d = Outside diameter of the "go" (inner) conductor If you did splice a piece of coaxial cable this would definitely change the characteristic impedance and the dB loss per a known length as prescribed by the manufacturer would also change. Best Regards K4RFE Larry (Retired RF Engineer) |
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Yes it can be spliced. Yes splicing it will cause some extra loss. If that extra loss is acceptable normally depends on the frequency of use. One thing to remember is lower frequencies mean lower loss in most cables so I'd use this method only below 10MHZ. However when confronted with replacing a very short part of damaged coax I found that a splice seemed to work just as well as the orginal one peice length. To make it work at all one must disect a peice of spare cable equal to the one being spliced. Use the center insulation, braid, and center conductor to transplant the damaged section of cable. If the physical parts can be replace in a manner where the geometry of the cable is little changed it will work. That takes some doing but can be done. As mentioned by others using two female and four male couplers is a better way, but that's not always possible in a hurry or when a very small rigid section is to be replaced. |
