Amphenol Adventures!

If you tinker with phone systems, you’ll be familiar with Amphenol plugs sooner than later. In the telephony world, Amphenol is a generic name for a 50 pin connector to plug into traditional analog or digital phone systems. I believe Western Electric came up with the plug, but Amphenol was a major manufacturer of the telephone connector, which is why the name has stuck around.

Amphenol connectors are also known as RJ21, a Registered Jack by the FCC used for multiple lines under 1 cable. There are 25 pairs, and in some cases you can have up to 24 lines, telephones, trunks, etc. The latter 2 wires are for ground (or just lazy wires.) Some systems may require more copper to power a telephone (literally or figuratively) or the types of trunks used.

For most modern deployments since the last 20 years, you can get one Amphenol to power at least 24 sets, trunks or lines.

In this installment of Amphenol Adventures, I’m documenting how I was able to cut a 50 pair Amphenol cable to use a RJ 45 patch panel to connect telephones to an Avaya system.

I’ve had some mixed results using 66 blocks. But I am not getting rid of them entirely. A PBX I got recently from someone who engaged on this site had a very long Amphenol cable. This double length cable was getting in the way of things. And because I wanted to try an experiment with using an RJ-45>Amphenol to the Avaya PBX, I thought it shouldn’t be too complicated, and hell if I break it then I’ll buy one!

The project began with me doing research on how to punch down the various wires so when I plug in a set to the patch panel, I will get a dial tone.

IMG_7585 Folks, this is what a 50 pairs of wires looks like. Boy is it confusing when you start.

IMG_7583 The wire scheme is typically a pair of solid colors Violet, Red, Green, White, Blue, Spade (or Silver) and Black and pair of colors with stripes of the same colors. The Amphenol connector splits the pair on each side. For instance, if you have a multi line 500 telephone with an amp connector and you just want line 1 to work out of the box, push in a wire on the connector on Pin 1 and 26 (to the phone that’s Line 1.)

When I read the specification or schematics, I say out loud Yellow on Blue (referring the stripe color first – or at least how I take it)

IMG_7589 I started doing this by one pair at a time. I looked at Avaya’s wiring specifications for tip and ring colors and punched down the two tip and ring (in this case for their DCP sets) on Pins 4 & 5.

When I went to the PBX and plugged it in this morning, I realized I was plugging this male to male. I had to perform a Catlyn Jenner procedure to make the panel transgendered! (I can’t resist that joke!) I didn’t want to wreck my work I spent time into early morning, but in fact I had to, because to transgender the Amphenol connector would be too complicated, so I found the other half with the female connector and redid the wiring. When I redid this, I learned when I laid down the first pair, the ring pair was basically the reversed color. Basically if one jack had a red/black for tip, then black with red stripes was would be for ring.

IMG_7593 While I was laying down the first pair, I took a picture of this to show how color blind I was, if this was Orange on Orange or Red on Orange?


Before I realized I was created a homogender plug, I thought of taking the other half pair of wires and plug them onto a far side of an extra 66 block and plug in phones on the center blade. Basically this 66 block would be hard wired to the PBX, previously the setup had an Amphenol on the side block with that going to the PBX’s Amphenol jack

Another note is that the old Apple Macintosh SCSI cables look like a 50 pair cable if you just cut off the 25 pin connector. I have not done this only because I am keeping those cables if I find a CD ROM drive to run old Mac apps. Theoretically the female end of the SCSI cable can plug into a PBX, but whether or not it has all the wires of 48 or less, I’ve not attempted. If you had used Apple SCSI cables in lieu of a phone cable, please opine below!

Punching down RJ45s for a number of years is easy, but 66 blocks is different. You need a different punchdown blade and its more difficult if you are wiring a plug. It however teaches you fine motor skills and most importantly patience. If you are an aspiring telecom guy or girl, this experience is mostly best done in trial and error.