Having problems speed matching a pair of Athearn BB F7's both run a DH 123 decoder.
A unit was way slower at full power than the B unit.
B unit was way slower in the mid range than the A unit.
After messing with them a hour or so I have them sort of close. Here is there CV's as of now.
A Unit B Unit
CV 2 3 20
CV 6 107 171
CV 5 255 170
Weight 16.5/8 oz 13oz
When I was setting CV 5 I had the DT 400 at 99% power.
When setting CV 6 I was using 55% power on the DT 400.
Now mid speed is just about the same as top speed. Am I adjusting the CV's at the right % of power?
With the B unit being lighter explain why It was so much faster when CV 5 was sat at 255? I would not think so. Plus that does not explain why at mid range, the A unit was way faster.
A unit is a Super Weight Athearn and the B unit was a dummy I installed gears and motor into. Both engines are about as quite as a BB could be. Both motors stalled well under a Amp, so I thing the motors are good.
Could the gearing be different from each other? Gears came from a older None Super Weight F7 A I got of E Bay.
Thank you for the coming answers.
Ken
I hate Rust
For consisting you only have to be close and not necessarilly exact.
There are several things that can cause the speed differences including tolerances of the motor and decoders. The gears could be different. When they are the speed difference usually increases over the speed step range.
The best way to match if you want close to exact is by adjusting the speed tables of both. Always match the fastest loco to the slowest.
Springfield PA
Any chance you have JMRI Decoder Pro on a computer connected to your layout?
That is what I use. And for speed matching, I use a loop of track and set up the user speed table in the decoders. That is what works best for me. Before that I didn't have much success speed matching anything.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
You have CV6 higher than CV5 in the B unit, that's goign to have some odd effects, mid can;t be higher than top.
CHeck CV54 and make sure it's 0 or 1 so torque compensation is on for both locos, that will make a HUGE difference.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Blue, how close is OK
Gandy My test track is a 9 X 5 oval and I am just using the DT 400 to change CV's. I then read the CV's using Decoder Pro, but is not hooked to the layout.
Randy, thanks on the CV 54 tip, never knew it was there.
Will work on them again Saturday.
Thanks for all the answers!
If you lose an inch every few feet that's close enough. Some people run with it more. Once the drag of the rolling stock is added things even out anyhow. If possible the slower of the 2 should trail but it's not always possible (such as an A and B unit).
Randy I just read CV 54. On the A unit (the slower of the 2) it was 60? How it ever got sat at 60 is beyond me. The B unit was at 0 (it was the one that would jump and was way faster.
I now have the CV's at he following on both engines.
CV 2 8
CV6 125
CV5 255
CV 54 1
I did forget to turn off DC mode.
All so found the A Unit (the slower top speed) has a DH 163 and the B unit is a DH 123.What CV turns off BMF? Or should I leave it on?
Will test them Sunday.
With me using the DT 400 and it power scale reads from 0% to 99% power at what % of power should I adjust CV2, CV 6 and CV 5?
Thanks folks for all the answers!
If both decoders have BEMF it isn't too big an issue, but sometimes if both engines have it and the sensitivity is set too high, they can end up "fighting" each other.
Also, don't forget CV 3 and 4 (momentum). If one engine starts a little earlier than the other, you can add some momentum to CV3 so that engine starts a little bit less quickly. Same with coasting to a stop, adding or reducing the amt of CV4 can really help get them working together.
KIM you're never going to get stock Athearn BB engines to be as good as say Atlas engines, but they can be qutie good especially with a good decoder. I have some Athearn F7 BB sets where one engine has a stock BB chassis and the other is a Genesis chassis I bought to replace the dummy engine's chassis. You can get the BB engine to play pretty nicely with the Genesis one...or at least to stay out of it's way enough that they work well together.
For BEMF go to this site and download the decoder manual. You'll find the info on page 58. If the speed issue is fixed then leave BEMF off for consisting.
http://www.digitrax.com/v1/dh163d.htm
This is an interesting thread to me because Im having trouble consisting an older Genesis F3AB set with a newer Genesis F9A unit. Im planning on switching out the crapy stock sound decoders with Tsunamis eventually, which should solve the problem ,but until then.............
Latter today I hope to give it another try with the speed matching. But there is one question I have that has not been addressed. What % of power should the throttle be sat at for which CV?
My Digitrax DT 400 shows 0% to 99%
CV 2 I think the goal is to get the engine moving at 1% Power
CV 6 What percent say 49%
CV 5 With it being top speed, 99% power on the throttle?
If B unit still jumps (I will turn off DC first) what cv should I adjust? CV 54 is now sat at 1.
Thank you all for your answers.
cudaken Latter today I hope to give it another try with the speed matching. But there is one question I have that has not been addressed. What % of power should the throttle be sat at for which CV? My Digitrax DT 400 shows 0% to 99% CV 2 I think the goal is to get the engine moving at 1% Power CV 6 What percent say 49% CV 5 With it being top speed, 99% power on the throttle? ...
cudaken... If B unit still jumps (I will turn off DC first) what cv should I adjust? CV 54 is now sat at 1. Thank you all for your answers. Ken
CSX Robert, thank you for your answer as well. I all wise wonder what % of power CV 6 should be set at. Far as CV for kick start, well there is another one I need to check. From my limited understanding of Kick Start, it gives a quick power boost to help motors start to spin. Is it not about the same thing as CV 2?
Thanks again to all the people that took there time to answer. Never had this much problem speed matching a engine before.
Confused again (not as much as I was) Ken
Not quite then same. CV2 is the minimum voltage the decoder will apply to the motor and the voltage will only go up from there. The kick start is a momentary jump in power. For example, when going from zero to speed step one with no kick start., the decoder simply applies the voltage calculated using CV2, and then will increase as you increase the throttle. With a kickstart value, when going from zero to one the decoder momentarily applies the kick start value, and then goes to the CV2 value and continues as normal. The kickstart value is only used when going from stopped to any speed, and only used momentarily.
Some locomoitves take quite a bit more voltage to get moving than to keep moving, i. e. you have to turn the throttle up to get it moving, but then you can back off some and it will keep going at a slower minimum speed. The idea behind the kick start value is to apply that higher initial voltage to get the engine moving, but to still be able to have a lower minimum voltage once the loco is going.
Robert BMF CV was sat at 6, changing it now. Will report back later on how the A unit runs.