Because I’m a sucker for accessories for tools, I bought a Fluke TN2100 “Enhanced Terminator Far End Device”.

This device was made to go with the Fluke CopperPro Series II (Aka Fluke 990DSL), and is required for doing certain qualifications on the line, such as profiling the behavior of the line at different frequencies, wideband noise levels, etc.

This is all to qualify the quality of a loop / pair (or pairs – Can do up to 2 pairs / 4 cables) as being capable of supporting a variety of services like A/V/DSL as well as E1s / ISDN services, EMF, etc, etc.

It’s a super useful feature, if your loop is rubbish, putting an E1 circuit on it will end up with a high bit-error-rate, and putting a DSL circuit on it will see it constantly loose sync, so being able to qualify if the loop is any good beforehand is a must.

Alas the unit I’ve got came from eBay, and didn’t come with the leads, there’s just an RJ45 port on the terminator, with no indication as to what’s what.

So here’s the answer (which isn’t in any manual I could find) which I found through trial-and-error and cracking the case open to work out what was what:

RJ45 Pin	Function	Colour (T-658A)
1	Blue Pair 1 (A-Leg)	White-Green
2	Blue Pair 1 (B-Leg)	Green
3	Yellow Pair 1 (A-Leg for Exchange Passthrough)	White-Orange
4	Yellow Pair 1 (B-Leg for Exchange Passthrough)	Blue
5	Red Pair 2 (A-Leg)	White-Blue
6	Red Pair 2 (A-Leg)	Orange
7	Unused	Brown-White
8	Earth	Brown

Hopefully of some use to some one.