I have a pair of Intermountain HO scale F3A and F3B locos. I installed Digitrax DZ143PS decoders because these were recommended by Intermountain on its web site.\
My impression is that the locos run slow at top speed, not a crawl, but slow. They are not in any danger of flying off the track on curves.
The default settings for CV2, CV5, and CV6 are all set to zero.
Is this decoder underpowered for the HO scale locos?
Rich
Alton Junction
I don't think it's the decoder. I have a couple of Intermountain locomotives that do run quite slow compared to other brands -- I think it's their gear ratio.
cacole I don't think it's the decoder. I have a couple of Intermountain locomotives that do run quite slow compared to other brands -- I think it's their gear ratio.
cacole, that is actually what I think too. But I have to wonder about the undersized decoder. Or is it?
Size doesn't matter - Except when the quest for "small" means components that can't handle the expected load. Then the decoder would overheat and either shut down (if it has thermal protection), or fry itself. But in either of those cases, the loco wouldn't slow down, it would just stop.
The DZ143PS spec sheet says it's rated at 1.25 amps continuous and 2 amps peak. If your F3's running characteristics are anywhere near normal, they shouldn't even approach those current draw limits.
As an aside, I have about a half-dozen DZ's in various HO locos, including a DZ143 in an old Con-Cor SW7, and they all run just fine.
So, we are back to the slower gearing on the Intermountain F3s.
Higher gear ratio's have better low speed control and more pulling power than lower gear ratios, that have a faster top speed. For instance, 12 to 1, faster, 18 to 1, slower but better pulling power, the motor turns 18 times to one full revolution of the main gear.
Building truck rear ends, race car rear ends and playing with Toy trains almost my whole life.
Old Man,
Frank