Cable Length for DCS

[bluelinec4]

Does any body know what the maximum cable length for DCS is. The cable in question would befrom the TIU to the track using 14 gauge wire. How far will the TIU drive the signal reliably. There probably will be 8-10 home run cables from the same TIU port. Does MTh publi***his anywhere

Ben

[Anonymous]

Bluelinec4,

I do not know what the maximum length is. I used to do a lot of testing in the backyard-setting up large loops and trying to pu***he envelope. I have not had the opportunity to do this recently.

My largest loop is 25' square, there are 8 drops to the track of 14 gauge wire. The MTH Power distribution channel is in the center of the layout. Each drop is 15' long. Each ends in a lighted lock-on. The layout is divided into four blocks. There is one lighted lock-on/one drop at each end of each block. There is a 5' long, 14 gauge wire running to the TIU. This loop uses only one port on the TIU.

We seem to be unable to get less than a 10 on the signal strength test. This is probably gross overkill, but it is a public display layout and has to work correctly every time.

The length of the individual track blocks seem somewhat critcal on a large layout. The blocks are defined by using insulated pins at each end. I did notice that until a loop gets up to around 70-80 feet, no blocks were even necessary, at least with tinplate track. Once you get to roughly that size or larger, the signal strength tends to degrade (at least in my experience) due to what has been explained to me as signal reflections and standing waves. Break the loop into blocks, and the signal strength comes back up.

You might look for Barry Broskowitz's "Commandments" on the OGR DCS Forum-it is a very enlightening document.

If you are already past all of this, I appoligize for bending your ear.

Thank you.

[bluelinec4]

Thanks RAK
No I am not past that point. I am just getting started. I don't know if I should put the TIU's on either side of the layout or all in one spot. Its not that big but I was wondering if there was any limitations. The longest cable run if I put them all in one spot will be about 60 feet.

Ben

[Anonymous]

Ben,

The information that I recieved when I was planning the display layout was to keep the wire running from the TIU to the MTH Power Distribution Panel as short as possible, to use either 14 or 16 gauge stranded wire and to mount the TIU in the center of the layout (if a large layout) if at all possible. I have also read (on the OGR forum) to place the TIU's in locations central to the area of the layout served, then run them in "Super Mode". You want to keep the length of the wires as short as possible, when possible. I intentionally made all the cables to the track exactly the same length-I do not know if this is significant but DCS signal strength is excellant. As a side note, of late there has been discussion on the OGR Forum of Super Mode working better with TMCC with a "common ground".
From personal experience, I have learned to mount the TIU's vertically (as opposed to laying them flat) and to keep them in "line of site" (not under the table) for optimum range between the TIU and the Handheld. We usually check the range at train shows and, in "line of sight" can still control things from about 100 feet away.

One also should mount the TIU's where they are easy to get to, remove and replace for those occasions where a software upgrade is desired or a fuse needs to be replaced. Mine are mounted with velcro, if that helps.

Regarding your ultimate question, you may simply have to resort to testing to see how far you can drive the signal. I did a lot of this in the backyard last year to obtain the optimal wiring plan for my layout. Some people advocate soldering track joints to improve signal strength-I tried this and, in the short term, it had no effect. I suspect that it would make a difference on a permanent layout where the track pins might get the chance to corrode, etc.

If you do start testing, I would be very interested in your results.

Good luck with things!