External Antenna for TIU

With some minor mods you could connect a coax connector to the top or side of the TIU and run it up to an external antenna.  I believe the remote to TIU is a 900mhz link, so that would be the antenna wavelength to use.

GIiven that the signal travels from the TIU to the loco by wire, not via radio, the signal loss isn't there (unless you have a wiring issue.  The issue would be between TIU & remote.  My experience on my layout is that if Mt. Chickenwire (a mountain made with plaster over chicken wire) is between the remote and the TIU, the signal is impaired.

 

I have aklso found that if I leave some electronic eqpt atop the TIU (like a spare remote) the remote-TIU signal is attentuated

Correct, but I'm assuming that if he's putting it in a steel enclosure, that he's going to have a serious remote to TIU issue, no way that's going to work well!  The metal enclosure shouldn't have any effect on the wires going to the layout from the TIU.

 

Once again, John, you agree with me.

No reason for TIUs to be other than on the layout.  If security is an issue, quick disconnects can be used.

I like to be agreeable.   Well, especially if you're right.

John, you mentioned minor mods to connect a coax connector to an external antenna. Could you, or anyone, give me specifics on what the modifications would be. We are not fortunate enough to have any electrical engineers in our club, just a couple of guys who mess around and try to learn as we go along. 

 

Thanks

 

Dick

If you try to increase the length of the antenna wire from the transceiver board you will run into issues.  MTH does not recommend doing that. R & D wants that wire to stay at the issued length.   Open the vent holes up on the TIU case and very carefully pull the entenna wire through and have it stand verticle.  This will help. 

John is correct on the communication issue with a metal cart.  If anyone tries the antenna mod, be careful not to unseat the transceiver board of you will rip the ultra thin traces off the board and need a new TIU.  Doing any work around that board is tricky.  If possible while trying to raise the antenna, have another person hold pressure downward on the board.

Like Marty says, the antenna is a critical piece, but it's not impossible to extend it. Extending it is also a bit of "trial and error" getting the best performance.

 

Basically, you'd have to run a coax from the board (grounding the shield to the analog ground of the board.  The cable runs to an appropriate connector, a standard co-ax connector would be fine, like the reverse-SMA that is used on many broadband routers.  You run a coax cable to a 900mhz antenna, this is one of many that would be suitable: http://www.ebay.com/itm/900MHz...;hash=item4d0c7055b6

 

This mod would also obviously void any warranty you have.

John, MTH wants it to stay at that length.  They are OK with extending it outside the TIU case.  I have my antenna outside the case and can hit the TIU with my remote from a good distance. 

Of course, Marty, your TIU wasn't inside a steel case.

 So what's he getting? Out of RF range? or no response? or what exactly??

Dave, thank you for your clear and detailed reply. From your answer, it is clear that the mods you are talking about are beyond my range of comfort and competence. I currently have a tiu at MTH for repair. When it comes back, I will contact you.

 

Dave's answer is exactly what I was saying.  I realize that it would void the warranty, but it's possible to extend the antenna.

 

The reason you might want to do this is as described in the first post of the thread, when it's installed where there is poor signal propagation.

 

Dave, what exactly do you mean "the length of the coax is critical"?  I realize that you'd have mechanical issues, and you have to properly wire the shield to the circuit ground, but I'm confused about the length statement.  Is this just because of the concern that you'll dislodge the transceiver board?

Thanks Dave, kinda' what I thought.  Yep, working on PCB boards requires some skill, you are correct. 

 

One thing you could do is use some finer cable like RG178 which might make the internal wiring a bit easier.

Dave, Jason was always very firm about not extending the length.  As you and John stated, doing any work on that would be a tricky job.  I have a new Rev L TIU with the antenna wire still inside the case and have no trouble hitting the TIU from 86 feet away.  This was measured from my TIU to my property line.  It may go past that but I can not take it to my busy street.  Some night after midnight I plan on checking that.  My home is a split ranch with the layout on the bottom.   I was going to do the antenna modification through the case and will not bother now.  Again, this is a new REV L.  Last Friday night I was at the NJ-Hi-Railers and the building they are in is 185 feet long and they hit the TIUs with no issue.  Standard antenna.

 

We have all seen people have problems that mount the TIU in the wrong location. 

I'll admit, we had the TIU on our modular club location down low in a corner and it was a problem.  I put it up on a shelf about 3 feet above the track height, no more issues.

Marty;

Remoting the Receiver board is a possibility, but it will depend on the type and strength of the signals between the Processor board and Transceiver board.

If they are digital you will need a special type of cable between the two that avoids crosstalk between wires. That type cable is a special pain to work with.

It typically requires crimped on connections using a set of special tools for each version. different ones for different numbers of wires & pins.

And all that is moot if simple wire resistance overwhelms the signal strength.

 

PS I still recall running my engine on your layout. You have an excellent setup.

Personally, I think just extending the antenna as Dave outlined is a better option.  It's just extending a signal that has known characteristics and is readily piped up on a single coax.

Russell, just a WAG.  I was thinking of a socket like a relay socket to plug the transceiver board into.  I have conversed with R & D about this.  My thought again is for all the guys and clubs that did not locate the TIU where it should be.  You will be surprised how many locate the TIU below the track and table.  On small layouts withoout lots of track people can do OK.  Not always so on large layouts.  I worked on a monster layout in Florida where the owner always had communication issues.  Moved the TIUs and all was good.

 

Dave should be able to shed light on this. 

I currently only use one TIU, but what about when you use more than one TIU and put   them in super TIU mode.  Do they have to be side by side or can they be 10 or 20 feet apart and increase range that way?

.....

Dennis

Dennis,

what about when you use more than one TIU and put   them in super TIU mode.  Do they have to be side by side or can they be 10 or 20 feet apart and increase range that way?

They can be placed anywhere. TIUs do not communicate with other TIUs, only with remotes.

 

This and a whole lot more is all in "The DCS O Gauge Companion 2nd Edition", now available for purchase as an eBook or a printed book from MTH's web store site! Click on the link below to go to MTH's web page for the book!

To be honest Marty, I never considered relocating the entire transceiver board.  The communication between the transceiver and mother board is digital.  As Russell pointed out, that would make it susceptible to cross talk if you used ribbon cable and IDC connectors to make an "extension cord."  I think in most cases you would still be better off extending the antenna lead with coax.  It not only performs well, but all the hardware outside the TIU case is quite robust.  If you protected the transceiver board inside a building it would probably be OK.  Like anything, the quality of the execution would make or break the idea.

So what's the problem with range then?  Just add another TIU.

.....

Dennis

Dennis,

So what's the problem with range then?  Just add another TIU.

Adding TIUs doesn't do anything to improve communications between the TIU and the remote.

How about connecting the remote to the tiu by a long wire or is that a dumb question.

Not dumb at all.  It's called tethering and has been discussed in many posts.  But you lose mobility.

Uh excuse me but, I thought the problem was distance from the TIU on large layouts?  So why doesn't it help to add another TIU closer to the other end of the layout?  Otherwise what is the point of having more than one TIU?

.....

Dennis

The issue is that the remote communicates directly with each TIU, so if one is out of range, having a closer one doesn't help communicate with the far TIU.  The point of having multiple TIU's is each channel can only drive so much track, as well as the 10A maximum current capacity of the channel.

 Well, if modifying the TIU is too delicate a procedure, how about just modifying the remote's antenna. Seems to make a bigger difference.

Thanks gunrunnerjohn.  You're the first one to understand my confusion and give me an answer that helped.

.....

Dennis

Absolutely it helps. we have 4 tiu in 4 different locations ,  since tiu do NOT communicate with each other, the remote must be in range of the tiu 's track the train is operating on. Sometime you may have to walk closer to the tiu. The question is.... what's the best range  without the remote pointing directly at the tiu???  10 feet 25 feet 50 feet 80- feet??? We've done the antennae mod by sticking the thing up through the tiu casing so it's pointing straight up and the tiu are  on top of the layout sort of hidden in scenery but accessible.

The train room is 80 feet long and we have range of all the tiu if necessary. When running  the trains you kind of walk around following them around anyway.

Would the tiu be better in one general location? don't think so just because of the wiring involved.

Gregg,

Absolutely it helps.

No, it does not!

 

Adding another TIU does nothing at all to assist in communications with the first TIU.