The DT400R radio throttle is the same as the DT400 infrared throttle, except that it has a radio transmitter instead of infrared emitters. The information on this page will dwell on the "radio" aspects of the DT400R. Refer to the DT400 page for all the other DT400 specific information.

The notable differences between the DT400 and DT400R are:

This throttle is available with two different frequencies. The A (standard) frequency is 916 MHz. Since this is the same frequency used by the DT100R and DT300R, this means you can use the DT400R with the same radio receiver as used by those radio throttles.

However, this is also the same frequency as used by the 916 MHz Train Cam (the new GHz Train Cam is recommended, and has no interference). Digitrax's radio equipment is also available with a B (optional) frequency. If using B frequency throttles, a B frequency UR91 radio receiver is needed. The B frequency throttles and receiver are special order items.

Because the "B" frequency is special order, and all future purchases have to match, we recommend you use only the "A" frequency equipment unless you have specific problems to solve.

The nine volt battery (standard alkaline or Ni-Cad rechargeable) has a life expectancy of about 20 operating hours. Of course, use of the flashlight when unplugged will also use the battery. When not in use for about three minutes, it goes into a battery saving mode which extends battery life tremendously. To wake it up, simply turn one of the knobs and wait - from one to ? seconds. The throttle can be configured to not use the battery saving mode if desired.

Like the IR throttles, this is simplex (one way) communication - from the throttle to the UR91 receiver. This means that any operation that needs two way communication (such as loco selection and programming on the programming track) requires the throttle to be plugged into LocoNet. Because of this, Throttle Knob Recall is disabled when operating in the Wireless mode. This means you'll have to be plugged in to use the recall feature.

Radio transmission is omnidirectional, whereas IR is line of sight except for reflection off smooth walls, ceilings, or other objects. It has a range of about 300 feet in open air. However, obstacles in the way, or interference, will reduce that distance. The more dense the object, the more the distance will be reduced. While the signal will go through framed walls quite easily, solid metal will block it all together.

Further, large metal items in the room with the system can cause ghosting which can hinder operation. Sometimes, simply moving the UR91 to a different location is all that's needed to solve the problem. However, sometimes a second UR91 may be needed to provide 100% coverage.

When taking your Radio throttle to another layout that doesn't have a radio receiver, you have two options: take your UR91 with you (it is easy to disconnect and reconnect), or connect an extension cord to the DT400R's one foot cord, and use it as a regular walk-around throttle.

We offer a coiled cord (on page ten) to extend the one-foot cord if needed. It's attached with a six wire Fem/Fem connector, which we also offer. See page ten for more information.

Digitrax has announced that they will release a DT400 with a Duplex radio system, thereby providing two way communication by radio. If this transpires, it will not be necessary to plug in each time you need to change locos, or use the recall button for the last loco. We assume that it will be necessary to plug the throttle in to log onto the radio receiver to get its ID code. But, once done, it shouldn't have to be plugged in again for the entire operating session. It is also assumed that the DT400 with Duplex radio will cost more. It will be on a different radio frequency (in the gigahertz range), requiring a different radio receiver/transmitter than the Simplex radio system.

Here's how to get that feature:

Adding hex 80 to the Option #3 value in the DT400 activates the pressure sensitiveness of the Function 2 button. This means that if you currently have x14 there for back light off, 24-hour clock format, recall stack depth of 8, and no tetherless release, you would put x94 in to still have all those features and a pressure-sensitive Function 2 button.

If you don't know how to do that, following is a step-by-step procedure:

1) Press and release the OPTN button. This places you in the configuration mode at Option #1.

2) Assuming you don't want to change Option 1 or 2, press and release the ENTER button twice. This places you at Option #1.

3) Add x80 to the existing value by turning either knob to the right. It will take a lot of knob turning to do this.

4) Press and release the ENTER button enough times to get through the configuration mode, back to loco operation.

With this successfully done, you not only will hear the pitch change of the compliant sound decoders, but can see the change on the display. The bar-graph, which goes up and down as you give the loco throttle, turns into a pitch bar-graph showing how much pressure you're applying to Function 2 when using that button. When you release that button, it turns back into a throttle bar-graph.

Even if you don't have a sound unit that can use this feature yet, you can play with it and see it work. By activating this feature, as outlined above, select any address and press the Function 2 button to see the bar graph move as you apply and release various pressures to the Function 2 button.

It's OK to play with for kicks, but if you don't really have a sound unit that can use this feature, I suggest that you turn it off after playing with it. It does add extra LocoNet message traffic that's not necessary if you don't need it.