A quick look at a short (and shady) Thunderbolt extension cable

(Not to be confused with similar looking USB-C extension cables, which will not extend a full speed 40GBps Thunderbolt link)

HuaLong Thunderbolt extension cable. Complete with a misappropriated Thunderbolt logo.

It’s no secret that I’m fan of “forbidden” Thunderbolt products. I mean hey, if you’re going to lock down a system to the extent that Thunderbolt is, it’s always going to be interesting to see illicit items for sale. Today, it’s a teeny weeny 15cm (total) extension cable I bought off eBay, shipped from China.

Marketing image provided by the manufacturer. This man appears to be very happy for an extra few inches. HuaLong is hoping you will be too.

If you ever found yourself looking for a Thunderbolt extension (male to female) from a reputable re-seller, you will have noticed that there aren’t any. It’s not that it hasn’t been thought of, it’s actually that such an item is forbidden by the standard, and would never pass the Thunderbolt certification programme.

The data rate of Thunderbolt is so high that adding any extra length or an extra connector into the mix may mean the signal doesn’t arrive in-tact at the other end. Inevitably however there is a little bit of margin, so likely we can put an extra connector in the mix, as well as a little bit more wire. So long as it’s properly designed.

The maker of this cable has been pretty square with us, capping it at just 8cm (wire length). This means that it should work in most scenarios. If it were pushed to 20, or even 50 centimetres, the odds of it working would be greatly reduced.

But, it’s not about the length. It’s about how you use it. I already have a use for such a cable:

Boom. No more groping around at the back of that dock (or behind my home PC) to swap from my work laptop to my home PC. I’ve now got the input port out on top where I can get at it.

Bravo, anonymous people in China who came up with this. And bravo for amorphous rule of law of the land of the rising sun. May Intel’s lawyers never find you.

2 thoughts on “A quick look at a short (and shady) Thunderbolt extension cable

  1. By placing a TB3 dock in the middle of two cables, you can increase the effective cable length (not an inexpensive option but it works)

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