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Digitrax DT400R question

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  • Member since
    December, 2004
  • From: Louisville
  • 387 posts
Digitrax DT400R question
Posted by dbduck on Tuesday, December 25, 2018 2:10 PM

Recently I was invited to run with a local club. It was a bring your own loco & throttle.

I took my DT400R that I have had for a number of years. Came with a Super Chief set. My question throttle would not work in wireless mode.. only when plugged in. Had a fresh battery

I was told that the issue was that the club uses a UR92 (mine came with UR91) and that my throttle is not compatable with the UR92

Have not had an opportunity to try my throttle with the UR91 I have, to see if  they still work together

I was also told if I were to bring my UR91 with me next time, that they could hook it up and all would be fine

I would like to thank everyone in advance for any help  

UPDATE:   I tested my throttle with my UR91  seems to operate intermittantly. Can plug the throttle into the UR91 & it works fine , so i dont think its the cable connecting UR91 to main "brain"

Happy Holidays, Paul


  • Member since
    August, 2003
  • From: Collinwood, Ohio, USA
  • 8,164 posts
Posted by gmpullman on Tuesday, December 25, 2018 7:26 PM

Hi, Paul

I had used my DT400 throttles for years using two UR-91 recievers on my layout. Reception was very reliable. The layout shape is essentially a dog-bone with a basement stairway and utility room in the center so two UR91s covered each end of the room pretty well.

I then decided to upgrade to Duplex wireless. This uses a different frequency (2.4 Ghz vs. 900 Mhz) so is not compatible. I sent two of my DT400Rs to Digitrax for the upgrade to DT402D. IIRC it was about $30 each. At the same time I added two UR 92s to the Loconet while keeping the UR 91s active, too since I had several utility wireless throttles.

The reliability of the signal dropped dramatically with the Duplex frequency. I had to buy a third UR92, mount them toward the ceiling of the layout room and sometimes while standing within ten feet or the reciever they still won't respond to a signal (the white LED blinks rapidly, indicating loss of signal).

I did the firmware update to all related components and that did help quite a bit. Right now everything is working fine but I still get some signal interruptions.

If you don't forsee using Duplex wireless, your best option would be to get a UR91 and let the club wire it into their Loconet network. I'm surprized they don't already have a UR91 for reasons like yours where someone brings an older wireless throttle.

Hope that helps, Ed

  • Member since
    April, 2016
  • 571 posts
Posted by PED on Tuesday, December 25, 2018 7:26 PM

Your club needs to read the documentation on their UR92. Your DT400R is capable of working wireless via IR. That is what it is doing with the UR91....wirlessl talking via IR. Although the UR92 in the club has added capability over the UR91, it can also talk via IR thus your DT400R should be able to talk to the UR92 with no problem. If it is not working with the UR92, there is some other problem at work. As an example, IR signals are primarily line-of-sight. If something is blocking the IR signal between your DT400R and the UR92, it will either not work or may have intermittent connection via a bounced signal. The IR signal  can hit a object and bounce in a different direction. Sometime the bounce will make the connection while other time it will not. I can point my TV remote at a nearby mirror and change TV channels due to signal bounce from the mirror to the TV.

Paul D

N scale Washita and Santa Fe Railroad
Southern Oklahoma circa late 70's

  • Member since
    February, 2002
  • From: Reading, PA
  • 25,996 posts
Posted by rrinker on Wednesday, December 26, 2018 3:40 PM

 Yes but the IR is strictly line of site - the top of the throttle has to poitn right at the face of the UR92 for the IR to have a chance of working - and depending on where the UR92(s) are moutned, that might not even be possible in many areas of the layout. It does work in a small room, especially when the ceiling isn't too high and is either painted white or has white ceiling tiles so the IR can reflect, but go around a corner and be at right angles or more to the IR receiver on the front panel of the UR panel and all bets are off.

 You may have to enable IR in the throttle, or it may only be IR enabled and not have the radio on, if it didn;t work well with the UR91. WHen you tested with the UR91 - did you plug in a power supply, Digitrax recommends the PS14, or did you simply connect the UR91 with a Loconet cable? It really needs a power supply to work reliably. Also the throttle needs good batteries.

 In the throttle manual are the instructions to access the setup and enable radio and IR functionality. 



Modeling the Reading Railroad in the 1950's


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  • Member since
    November, 2007
  • From: sharon pa
  • 436 posts
Posted by gondola1988 on Sunday, December 30, 2018 1:06 PM

I had the same problem also, I put together a ur 90, a ur 91 and a ur 92an mounted them together and made a hanger for them in case I had to take them down. They are about 8 feet up the wall, my layout is u shaped and uses both sides of the basement. Since I did this we no longer have any reception problems, the basement is 40by 70. My buddy had the same problem until I did the same for him. Might be worth the try,Jim.


  • Member since
    July, 2008
  • 1,177 posts
Posted by mfm37 on Monday, December 31, 2018 11:28 AM
Looks like the club has gone all duplex radio. Your DT400R is a simplex throttle. Simplex requires the older simplex receiver (UR91) and they don't have them. Fortunately they seem to have jacks to plug into which is required with simplex to acquire an address. We do the same at my club-plenty of jacks but no more simplex radio receivers. Just a note that if you choose to upgrade your DT400R to a DT402D you will also need to purchase a UR92 to use the throttle with radio at home. It will still work plugged in and the IR will still be available. Martin Myers

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