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I have two unused coax cables in my the garage.
Considering that Ethernet uses only 4 conductors, can I use these two coax cables as my 4 conductors?
I could wire the ends to Cat 5 connectors.

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    Which ethernet standard? For example 1000BASE-T and 10GBASE-T require four pairs. Any of the fiber ethernet standards only need two fibers. 10BASE-T (10 Mbps) and 100BASE-T (100 Mbps) are pretty slow and outdated. Most equipment now comes with 1000BASE-T (1 Gbps) that would require eight conductors. It is more than a simple matter of conductivity. There are some stringent specifications that must be met for modern networking cable.
    – Ron Maupin
    Aug 1, 2017 at 1:18
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    Early versions of Ethernet (e.g. 10Base5) used 50 Ohm coax cable. Your coax is probably 75 Ohm impedance for TV signals. Use it to connect an antenna to your TV.
    – sawdust
    Aug 1, 2017 at 4:29
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  • This is NOT a dupe of any of the above - they were talking about using convertors, this question asks about crimping 2 coax cables on to rj45 ends.
    – davidgo
    Aug 1, 2017 at 19:43
  • IMHO the fact the OP has constrained answers to his proposed solution of crimping the coax to RJ-45 connectors doesn't change the fact it's a duplicate of a question asking how to make an Ethernet connection over coax. Aug 2, 2017 at 1:35

3 Answers 3

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You might be able to pass a signal, but I expect this will not work very well. For short distances the savings are small, and for long distances the problems will amplify.

CatX cable is designed to have low cross-talk by twisting the pairs to cancel interference. Coax is designed to shield the inner core by grounding the outer core.

You will also have difficulties crimping the cable.

It is possible to use an active device to use ethernet over Coax - over larger distances then you can get on regular Cat5, but this is using technologies to change the signal (ie its doing digital - analog - digital conversion.

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    New Cat6 would probably cost less than coax converters. "its [sic] doing digital - analog - digital conversion" -- FYI the Ethernet signal over Cat5/6 is analog. Actually all signals are analog because they exist in an analog world, i.e. they are continuous and do not have discrete levels. What is typically called a "digital signal" (i.e. TTL) is amplitude modulated, and has to be sampled. Gigabit Ethernet uses pulse-amplitude modulation; the Ethernet PHY is the modulator/demodulator.
    – sawdust
    Aug 1, 2017 at 3:31
  • I.e. digitally encoded information riding on an analog signal. Aug 1, 2017 at 7:51
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You can't turn it directly into Ethernet, but you could probably get Ethernet-like speeds out of it by hooking MoCA equipment to each end. Other transmission technologies that may have a way to do Ethernet-like speeds over 75-ohm Coax include HomePNA and G.Hn.

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    MoCA = Multimedia over Coax Alliance
    – Nayuki
    Aug 1, 2017 at 6:30
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As Ron Maupin mentioned, Ethernet has some very specific requirements for impedance, capacitance, and cross talk between twisted pairs, and each pair in a cable is twisted at a different rate of twists from its neighbors. It would be an interesting experiment, but I don't think it will work.

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