I have got a short length (1m) of standard fat CAT5 shielded cable that runs inside a piece of equipment before the signal exits via a bulkhead connector to a PC. It's the old kind that is a real pain to put a tight radius bend into. I was thinking of replacing it with thin CAT6 cable that has a very flat cross section and is extremely flexible.

The question now being, am I likely to experience any RFI problems from the cable to the surrounding electronics boards? It will run close to or on top of a single board computer. Data rates are low and the SBC connects with 100Base-T

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  • \$\begingroup\$ Is the thin Cat6 cable also shielded? is the shield bought out on a pin, to be controlled? \$\endgroup\$ Commented May 26, 2019 at 21:53
  • \$\begingroup\$ @analogsystemsrf I have no idea. It's just some off the shelf preformed cable \$\endgroup\$ Commented May 27, 2019 at 9:33

1 Answer 1


Cat5e, performs up to 100 MHz.

CAT6 is well shielded, with tighter specs on Return loss at 100m (-12 dB @ 100MHz) so I think that would perform well for 1m.

The specification for Cat6 features more stringent specifications for crosstalk and system noise and provides a performance of up to 250 MHz.

This was often achieved using a spline (a longitudinal separator) in the wiring, which isolates each of the four pairs of twisted wire. However, this made Cat6 cables more rigid; newer cables use other methods to reduce noise and are more flexible, which you seem to have found.

Wiki says Category 6 and 6A cable must be properly installed and terminated to meet specifications. The cable must not be kinked or bent too tightly (the bend radius should be larger than four times the outer diameter of the cable[10]). The wire pairs must not be untwisted and the outer jacket must not be stripped back more than 0.5 in (12.7 mm).

The kinks alter the impedance and balance but will not affect < 100 Mhz @ 1m .

The ground drain wire must be terminated to gain the effects of the shield.

Q&A info on CAT 6

  • 1
    \$\begingroup\$ I am curious how they can meet the category 6 specifications in a flat cable. Presumably possible if this is tested and marketed, so extremely clever. \$\endgroup\$
    – David
    Commented May 26, 2019 at 21:59

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