NCE DCC Decoder Tips

North Coast Engineering (NCE) has been making high end DCC systems for a long time. When I became disgusted with the Digitrax DG580L I went looking for another manufacturer of high current decoders. I found NCE.

NCE's decoders have one attribute that I find extremely valuable, they are tough as nails. Some of them were lacking on frills, but the main purpose of a DCC decoder is to drive a motor and the NCE decoders do that extremely well. In my experience, they are stone reliable.

I've used, and still use, 3 varieties of NCE decoder, the D408, D408SR and D808SR. NCE's numbering system is pretty easy to figure out. They all start with a "D", the next digit is the average current capability and the next two digits are the number of functions. The "SR" at the end indicates silent running.

Virtually all of information that is on this page can be found in other places on this site, but I am using this page to collect that widely spread information in one place.

• D408
• D408SR
• D808SR

North Coast Engineering made a decoder, the D408, that had the highest average current capability of any of the large scale decoders at that time. NCE uses Schottky barrier rectifiers to reduce the voltage drop and therefore the heat generated by the rectifier. I bought two D408's for use in the RS-3's that had smoked some Digitrax decoders. They both handle the RS-3's at maximum load with no sweat. Even though the PWM frequency is low, there is little acoustic motor noise. It runs perceptibly warm pulling 15 cars on a grade. The D408 is a workhorse, but it isn't packed with accessory features. There is no reversing headlight. Analog conversion of the D408 is marginal at best. It runs, but it only goes in reverse no matter what the track polarity is and it has no ability to set function output states when analog converted. The NCE decoder will operate in 128 speed step mode, but then the acceleration and deceleration rates don't work so I run them at 28 speed steps.

Overall I am very happy with these decoders and even though they are long of tooth, I have no intention of upgrading them.

The latest D408SR decoders are silent running (16 kHz switching frequency) and seem to have all of the high current capability of its predecessor. It has 15 special lighting features available on all function outputs. It also has a reversing headlight. Analog conversion now works. The acceleration and deceleration rates now work in 128 speed step mode as does the Vmax, Vmid and Vmin settings. The decoder can also interpret a speed table in 128 step mode. The D408SR is very good but it does not have BEMF.

The D408SR looks very similar to the older D408 but there are some visible differences.

There is a newer D408, the D408-E. I don't have one of these, but it does have BEMF motor control and is the same size as the D408SR.

In September 2002, NCE released a much heftier decoder than the D408SR. The new one is the D808SR. It is essentially the same decoder as the D408, just with a bigger heat sink and much bigger components. It is silent running at 15.625 kHz, however like the D408SR It does not have back-EMF motor control. There are 8 function outputs with 0.5 amp continuos and 2 amp surge capability on each output. Each function output can take one of 15 attributes such as a ditch light simulation.

The entire backside of the D808 is consumed by a metal heat sink. Under the heat sink are four 48 amp Schottky barrier rectifiers and four very large FET switches rated at 31 amps or better.

There is really only reason for the existence of this decoder. USA Trains uses insanely high current motors in some or all of their Diesel locomotives. I had a GP9 for over 4 years before NCE came out with this decoder specifically designed to go into those locos. As soon as the D808SR was available, I bought one for the GP9. It has worked fine ever since.

I also put one in an old Aristo Pacific that tended to lug a little. The thought that the D808SR might have lower voltage drop a high current than the D408SR (which is pretty low in its own right). The D808 ran the loco better when the motor was cold indicating that the D408SR might have been straining a little, but when the motor heated up and it's resistance increased a little, the D808SR did no better than the D408SR. A high capability decoder really cannot help a loco that doesn't have the basic motor capability to do it's job properly.