Could anyone suggest a good nce DCC card, no sound, for use with Q car powered tolleys?

The key to choosing a decoder of any brand is the current draw of the locomotive under load.    Decoders are rated for continuous operating current draw, and stall current draw.     If you can test the loco current and get these numbers, it makes a choice easy.    This is especially true if you want to spend less money, ie buy a decoder that can do the job, but not a much more expensive one that is more than you need.   

It is easy to test the  continuous running one with the amp meter in line with a power feed.    To test stall current you want to watch the meter while you push a piece of wood or something on the wheels to stop them or slow them down to almost stall.

That said the safest one I use for O Scale is the NCE D408SR.    This decoder has a 4 amp continuous rating and has been redesigned to 10 amp stall current.    This is more than enough for any loco I have seen.    I have a few very old Max Grey models and they draw about 2.0-2.5 amps under load and stall is much less than 8 amps - maybe 5-6.     So that decoder would probably handle any trolley.

I also have some newer locos that run at less than 1.0 amps and stall is less than 2.0 amps.    For these I can use an NCE D13sr (I think that is the smaller decoder model).  

many thanks