Bob, I do have another question about the B' K-27 Chuff. I've noticed with my P5 using the optical chuff that the chuff starts missing about 40% of full throttle and eventually cuts out all together. Are you using the optical chuff and if so do you see this also?
Tony, I'm running about 21 - 22v. There was an article in Model Railroad News that stated the Scale mph was 31 at 22v at full throttle on flat track. I have not verified this. There is a blurb on the Blackstone site that says the K-27 could get up to 45mph (based on what old-timers stated: reference ). My understanding is they typically ran at 20 - 25 mph, which according to the article in MRN would be about 50% of full throttle at 22v (23 scale mph). I prefer to run models similar to prototype speeds, but if I try and run at this speed the chuff cuts out, it starts cutting out about 40% of full throttle at 22v.
If i could get the chuff to not cut out at even 50% of full throttle at 22v I would be happy with that speed I can always go back to magnets but I'd still like to get the optical chuff working if possible, but I'm getting close to giving up on it. I see where others have had this same problem so I don't think my K-27 or P5 are defective.
My power supply is switchable and if I run 16v I can't get near what my locos run at 22v. So I'm sure those running at 14.4v would not see the problem even at full throttle.
I have the P5 connected using an NPN transistor, as that is what Pheonix says to use. Some say it is not needed, but when I called Phoenix (John) they said it is required for the P5 but not the 2K2. So I have not tried the install without one. Phoenix said they would send me a 2K2 to test to see if I have the same issue with that card, but I'm still waiting after 2 weeks.
I also tried a 0.1 capacitor. It helped very minimally in my case. Another theory is that since I run DCC that mabye it has some extra noise that battery or DC folks do not see?
I think you have done a great job with the RCS system, and as others have noted, I believe yours is the only true Plug-n-Play install for the K-27. Well done!
I'm not sure if the problem is I'm using a decoder that does not have a ground, NCE D408-SR? I don't know enough about electronics to figure it out. But I know you guys know a lot (Bob, Tony, Greg and others). So i was hoping one of you would figure it out for me
If the ground is important then I would have to switch to another decoder that has a ground. Or can I use the ground on the dummy socket some how?
However, I'm not sure why folks think the ground is important? If it were then why would the P5 work at all? If the P5 works up to 40% of full throttle at 22v then why would a grounding issue cause a problem at that point?
I would be interested if ANYONE said they had their B' K-27 running on DCC at around 22v was using the optical chuff successfully at full throttle or even close to it. If so I'd like to know which decoder and which sound system.
I really think it's because the optical chuff trigger is too short at higher speeds.