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Convert one A unit to a dummy or buy two decoders. How are you proposing to control two motors with one decoder anyway? Even if you could make it work, the total amp draw would fry most decoders.
These were high quality low draw can motors. With Athearn's you'll smoke the decoder before the locos get 3 feet. There's simply too much power draw for any HO decoder.
Two decoders would be the way to go. That way you can speed match the locos. If you make one into a dummy that'll just be so much more weight the powered unit is pulling and will result in less cars being pulled.
It's just that the first time you hitch more than three properly weighted boxcars to the duo and take them up a 2.5% grade you will be able to watch your nice locomotive ooze white smoke and possibly see the paint bubble.
Okay, maybe as many as five properly weighted boxcars. Maybe only two.
It'll work...if you find the right decoder....and if the decoder will fit in the shell. I read an article a while back where (for some reason) they chose to wire the layout DC, then used G scale decoders to power THE TRACK so the layout could be run by a DCC controller. In other words the decoder was running the track as opposed to an engine. I guess it makes sense if you have isolated lines on your layout where you run DC engines and others where you run DCC.....you could run everything with the DCC controller.....anyway, with the g scale controllers the person was running 4 or 5 engines with no problem. So you just need to find a decoder rated for enough amps for your 2 engines, and hope it's still small enough to fit.
You will definitely want to use 2 decoders on older Athearn locos. I've tried to run 2 locos off 1 decoder, and it may work for a short time, but you will end up frying it. I've MUed stewart F7's on one decoder with good results. Any of the newer locos can be MUed, but those old Athearn monsters are hogs that draw way too much amperage. Still, I agree that it's cheap enough to install a decoder in each loco now. If you plan on running F7's back to back, I suggest that you solder the black and red wires backwards on one unit, and connect the yellow wire to the headlight instead of the white one. Then just program both units on the lead units number, and they will work just fine together.
