How to make RJ11 or RJ12 ExpressNet Cable

Atlas' list price for XpressNet RJ11 cable is US 6.50 or about Can $10.00 per 15ft length. This would be EXPENSIVE for a moderate size layout. Therefore, my question:

How do you make your own RJ11 or RJ12 Xpressnet compatible cable? Are they simply 4 or 6 wire telephone cable with the end connectors reversed or are they special twisted wire cable with reversed end connectors?

The Atlas/Lenz literature says that care must be taken to use reverse style modular phone cables to interconnect the UNIVERSAL PANEL CONNECTORS. Looking at a piece of RJ12 cable I notice that the end connectors themselves are reversed (ie. upside down from each other) yet the cable itself looks like it is a simple 6-wire straight run (ie. coloured wire is oriented the same at each end).

Lenz's literature indicates that ExpressNet must use twisted cable. Given that the wires of my example cable is encased in solid black, I can't tell if the wires are twisted or if 'twisted" refers to the connectors.

Any help would be appreciated. Thanks

EWOR NOR

(name spelled reversed)

Reply to
ewoR noR
Loading thread data ...

Wires are twisted to reduce interference

Dan T

Reply to
Dan T

Six wires will be three pair. Each of the wires in a pair will be twisted around themselves. Cat3, cat4, cat5 have different numbers twist per inch (IIRC cat5 is 15 per inch, ethernet cable will be cat5, most modern telco cable is cat3).

You should try to avoid as much untwisting as you can near the connector.

Paul

Reply to
Paul Newhouse

Is there a need for using one of the "Cat" or "category" standard cables (more expensive per foot)? Or would any unshielded twisted pair cable set work? Even the standard telephone cable (round bundle not flat ribbon style) is twisted to a certain degree. I am not sure what the standard turns per inch might be or be needed but I know that twisted pair bundles are sold from 1 pair to 24 pair.

Reply to
Art Marsh

I don't know where the other two people who responded to your note got their information, but they are wrong. I just went and gave one a good looking over. I even cut one in half (I had to do this anyway). They are just standard telephone ribbon cable with reversed end connectors. There are no twists in the pairs.

Yes, your observation is 100% correct. You will notice that what this does is keep the wires connecting to the same pin regardless which end is plugged in. This "rule" I developed years ago working with computer networks will help. Hold the connectors with both pins up. If the white wire is to the right on both ends it is a data cable. "Pin up white to right" = data. If one of the connectors has the blue to the right it is a voice or modem cable.

Any time there is a digital pulsed signal on a cable it is better to twist it. Just because the Atlas cable doesn't twist doesn't mean you shouldn't. Our club has 100's of feet of the Atlas black cables, so based on that, standard 3 pair twisted phone wire should work fine. I don't know the DCC frequency but CAT-3 or CAT-5 would probably be better. There is the general trade off of increased attenuation and reduced cross-talk per twist, commonly known as the headroom of the transmission media. It just depends on how much you want to spend for twists. Just make certain the proper conductor goes to the proper pin in the RJ plug.

Personally, I am even twisting my wires from the power station(s) to the track. Others are doing fine with non-twisted and even big "antenna" common bus systems, but I am predicting they will begin having trouble as we put more and more signals over the system (like the NMRA RP 9.3.1 and 9.3.2 bi-directional feedback signal).

Reply to
SleuthRaptorman

The "Cat" is standard which specifies the turns per inch. The expense is a reflection of the quality/consistency of the turns, how well they are wrapped, etc. I picked up 3k ft of cat 3 for about $50, at Fry's, and used it as a demo for a two wire Tut Systems ethernet extender.

If you are going to "roll your own" make sure and include the cost of the crimper. If you are going to use a screwdriver you should practice on a few first. *8->

Good luck, Paul

Reply to
Paul Newhouse

SleuthRaptorman cried out

RJ11 and RJ12 refers to the type of connector and order that the wires are connected it. If Atlas claims the cable is RJ11 or RJ12 then yes standard two pair or three pair phone line should work.

Reply to
Rosco

AM>Is there a need for using one of the "Cat" or "category" standard AM>cables (more expensive per foot)? Or would any unshielded twisted AM>pair cable set work? Even the standard telephone cable (round bundle AM>not flat ribbon style) is twisted to a certain degree. I am not sure AM>what the standard turns per inch might be or be needed but I know AM>that twisted pair bundles are sold from 1 pair to 24 pair.

Art,

I use CAT5 cabling for all of my Tortoise switch machines and generally wiring. I picked up 1000' for around $60, which makes it 6 cents a foot. The nice thing about it is that you have extra pairs if you need them. The 4 pairs handle all connections to the Tortoise should I ever need them. I bring all of them back to split RJ66 blocks and then punch down the wires. I can use the leftover wire for throttle wiring, low voltage lighting and other things.

Jeff

Reply to
Jeff Binkley

Update - I contacted the club superintendent who has been working with Lenz and Atlas while installing this system at the club. Here is his response:

The twisting part comes in with extended length runs of the express net throttle bus. If your throttle bus is going to be 300 feet or longer you should twist the DATA pair. You do not need to twist the power pair. Atlas and Lenz engineers told me to use the "cheapest twisted pair wire available".

Reply to
SleuthRaptorman

I also have extra rolls of Cat 5 and some Cat 3 cable to use up as well. (But at the local Fry's it will run you about $25 /1000') and is planned for layout wiring. The original post just raised a question as I know that 2, 4,

8, etc. 22/24 gage shielded cable runs a little less than the CAT standard cabling. I wondered if there would have been a noticeable difference between the two types. I had also been reading about some quirks in DCC controlling as to wiring used. Not sure if that was on RMR or not.

Thanks

Art

Reply to
Art Marsh

Okay, but there are sub types to the two connector standards. You can purchase RJ11 (4 strand), RJ12 (6 strand), and RJ45 (8 strand) male connectors for both flat ribbon cable or for round bundled twisted/non-twisted pair wires/cable. But I was reading too much into the discussion I guess.

I was curious as to the possibility of a "need" for twisted pair (round) over flat cables. Flat is cheaper. And according to the thread here, twisted pair is only needed for runs over 300' which indicates regular networking signal strength limitations do occur. Will not affect me in the future as my runs should only be 75'-125' max.

Thanks

Reply to
Art Marsh

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.