Stewart DCC speed ranges F-3 F-7

[gmpullman]

Hi, Folks
I just installed a DH-123 decoder in a pair of Stewart F-7s. All went well and I programmed the address just fine. Now, when I test ran the engines, they take off at about 30mph on 1% throttle and stay at that speed until I run the throttle up to about 75%.
I'm new to DCC and this is the first time I've ever had this kind of wacky speed curve in about a dozen decoder installs. Is this a common thing with the Kato drive in Stewarts?
So, my question is, can anyone give me a Q&D on how to program the speed table CVs? Sounds tricky and maybe I'm intimidated about all the hexidecimal stuff! I use a DT-400 throttle on the Chief II command station.
Does anyone out there use a computer interface for programming CVs?
Thanks, ED

[cmrproducts]

Ed

Check the CV for the start volts (CV2 - I think) . It might be set at some other value other than 0 (zero). I have found a number of them come new in the package this way.

BOB H Clarion, PA

[gmpullman]

Thanks, Bob
I'll get out the Digitrax manual and give it a shot! I can't read the manual fast enough before the "time-out" period but I think the DT-400 won't time out until I hit return or exit, whatever... nice feature for us slow learners!

[rrinker]

And as to your last question - get yourself a Locobuffer and download a copy of the free JMRI from http://jmri.sourceforge.net. The DecoderPro tool will make things a lot easier, plus it keeps a record of all locos programmed through it, so if something ever happens to one, like it gets reset somehow, you can quickly and easily put it back to the way you had it. Plus no worries about timeouts - you can take your time changing settings on the various screens and when you are all ready, send ALL changes to the decoder atone time. And the screens change depending on the brand and model decoder - so you won't see options for things your model decoder doesn't have.
As for the loco - Bob's probably correct. I have a couple of Stewart units and they start nice and slow with CV02 set to 0.

--Randy

[johncolley]

I have a four unit Stewart FT ABBA with one B unit full of sound, the other three units are DH163D decoders. With my prodigy Advance set on 128 speed step I use SV at around 20 and get nice slow yard speeds except there is still some slight speedup/slowdown which I think is due to inertia with them being sluggi***o start when cold. I can pull out of the yard around 5 mph and once on the main I gradually go up to track speed 35 to 50 depending on where. On grades I slow to 10-20 mph. I strongly feel that the addition of sound makes me want to operate realistically.

[gmpullman]

Thanks to you all! I put the engines back on the programming track and set the CV2 to 00 and that did the trick! Those Stewarts ran like silk on DC and they're even better on DCC!
Thanks also to Loy's Toys who provided a Hints & Tips booklet with my Chief II and that explained the CV programming a little better!!!
I will definitely check out the Locobuffer and JMRI

[rrinker]

QUOTE: Originally posted by johncolley

I have a four unit Stewart FT ABBA with one B unit full of sound, the other three units are DH163D decoders. With my prodigy Advance set on 128 speed step I use SV at around 20 and get nice slow yard speeds except there is still some slight speedup/slowdown which I think is due to inertia with them being sluggi***o start when cold. I can pull out of the yard around 5 mph and once on the main I gradually go up to track speed 35 to 50 depending on where. On grades I slow to 10-20 mph. I strongly feel that the addition of sound makes me want to operate realistically.

Look in the Digitrax decoder manual in the sections on setting the Back-EMF CV's, there is a series of 3 CV's that control how the Back-EMF is applied. One digit of each CV affects the BEMF for the loco running solo, the other digit is for when the unit is consisted. For a consist, you are going to want to reduce or even turn off BEMF to eliminate surging and hesitation as the multiple units push and pull one another (even with all Stewarts, they aren't 100% identical. While over a long distance they may indeed stay right with one naother at the same speed setting, over the short term they will shuffle back and forth slightly. The one getting pushed, the BEMF will cause it to slow down, the one pushing, when it gets slowed, the BEMF will cause it to try to speed up. And it becomes a never-ending cycle as the units bang back and forth).
Is the B a powered unit with a sound and motor decoder, or a dummy with just a sound decoder? The motor drive in the Soundtraxx combo motor/sound decoders is VASTLY inferior to the DH163 and you would need to do a bit of tweaking to get them all to run together.

--Randy

[johncolley]

Randy, thanks for the tip. The B unit is a dummy with a DS150DX and 2 woofers and a tweeter. Gotta love it! I run it at around 50% volume (7 or 8 of a possible 16), and that is plenty in a sheetrocked room. The only thing is since my PC speakers are a lot bigger I don't get the bass in the soundbite on the locos that I do on the PC.

[rrinker]

Sounds good - I have a Stewart F7B dummy that i was thinking about loading with sound. I have pictures to prove that on the Reading, F3/7 B units were not just used in consist with A units, but also with GP-7's and other hood units - so I figure I can put sound in one unit and run it with others and it will be good. Sure beats trying to put sound in every loco I own.

--Randy