I have some small diameter coaxial cable, which we use in harsh environments. I want to buy connectors for it. Most suppliers list thousands of connectors by cable designation, so finding compatible connectors can be a pain if you don't know the number.

The layup of the cable is:

  • Inner conductor: 0.2mm/0.008" diameter stranded copper
  • Insulation: PTFE or FEP, 0.4mm/0.016"
  • Shield: braided copper, 12x100um wires
  • Jacket: PTFE or FEP, 1mm/0.04"

Anyone know what RG number, or Belden number I should select on my supplier's website? If anyone can post a link to a huge chart of coax designations and diameters, even better.

  • \$\begingroup\$ Is it white? Does it have anything printed on the cable? \$\endgroup\$
    – Mast
    Jul 8, 2016 at 10:49
  • 1
    \$\begingroup\$ Just use any connector that fits size, impedance and bandwidth \$\endgroup\$
    – PlasmaHH
    Jul 8, 2016 at 10:54
  • \$\begingroup\$ @Mast both insulation and jacket are clear and colourless, no printing. \$\endgroup\$
    – Jack B
    Jul 8, 2016 at 11:11
  • \$\begingroup\$ @PlasmaHH Yes. Most suppliers (RS and Farnell anyway) stock thousands of connectors and list them by compatible cable - so I'm looking for a quicker way than clicking every one in turn and looking at the dimensions in the datasheet. \$\endgroup\$
    – Jack B
    Jul 8, 2016 at 11:14
  • 2
    \$\begingroup\$ @JackB At £15/foot I would think the supplier would be happy to tell you what connectors are suitable, and maybe even sell you some. \$\endgroup\$ Jul 8, 2016 at 13:36

2 Answers 2


Look through a table of RG type specifications and find the closest match you can for inner and outer diameters, also matching the characteristic impedance. Then search for connectors that fit that RG type.

Be warned that the RG specifications were developed a long time ago and AFAIK there's no new RG types being introduced since many years ago. So microminiature cable types may not be covered by any RG type. Which will put you right back where you started, having to check each connector datasheet or a selection guide for the range of i.d. and o.d. they accept.

  • \$\begingroup\$ I've been having a go at this, but the smallest RG types I've found are at least 2mm. If you know of an authoritative or complete list, that would be helpful. \$\endgroup\$
    – Jack B
    Jul 8, 2016 at 16:21
  • \$\begingroup\$ @JackB, I'd look in the catalogs of the big cable manufacuturers (Belden, Alpha, ...) \$\endgroup\$
    – The Photon
    Jul 8, 2016 at 16:31

Old question I know.

I'm 99.9% sure that the cable in question is Lakeshore Cryotonics Type SC coaxial cable. It matches the various properties and it's made for the deep freeze.

But looks like they only sell pre-made cables with either BNC or SMA connectors.

Note: There is a 1.6mm coaxial cable that goes by the name micro-coax. But while the inner conductor is the right size, the sizes of the insulation and the jacket are more or less swapped. It is also 75 ohm.

  • \$\begingroup\$ It is indeed that stuff, we also use a lot of the SS type. We never found any BNC/SMA/SMB connectors for it, but MMCX designed for "H+S .047 flexible" fit pretty well. We settled for always fitting those, and sending out adapters as necessary. \$\endgroup\$
    – Jack B
    May 21, 2020 at 13:38
  • \$\begingroup\$ I was not expecting a reply 4 years later, but no one had actually answered itso. If you go look at some of their actually systems(where they are taking various measurements), you can find the pre-made cables for use with the systems. The thing is, 1.60 mm seems to be an oddball. From looking at the other cryo suppliers .80 and 1.80 are far more common as are the connectors. Something to look into unless you have to have that specific diameter. \$\endgroup\$
    – GB - AE7OO
    May 22, 2020 at 11:53

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