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June 16, 2006

Installing the  SDH104K1 Combo (SDH104K1 + FN04K1)A in an Athearn RTR Dash 9

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Submitted by Jim Oliver

Just wanted to add some observations/comments on the newly released sound decoder from Digitrax.  I was a bit cautious about this as it was more specific for the Kato unit, however, I wanted to install it in my Athearn RTR Dash 9.

After looking at the instructions, as well as a Kato demo unit, I felt I could tackle this.  The big problem would be the speaker, but I'd cross that bridge later.  First, I removed all the wires to the Athearn jumper board with the DH123 decoder I'd previously installed.  The one thing I don't like about Athearn is the use of the frame for track power, so this was now removed.  The wires off the trucks were too short, so new ones were solder in the old one's place.  I then soldered new wires to the metal plate on the truck for track power from the left side.  This gave me four wires; two per truck for right and left pickup.  Next was to solder a wire to the top of the motor (the Athearn jumper board acts as the negative contact).  I noted in the instructions, as well as the demo unit, that Kato has two small tabs that 'plug in' to the bottom of the decoder.  Rather than use a screw as suggested, I gently applied a dab of solder into the hole, using a low amp rechargeable solder tool.  The solder is applied to the tip, then to the hole.  This prevents any heat build-up.  Next, install the four track wires under the small sprung clips.  I then checked for orientation of the loco on my test track.  Success!  It ran in the right direction.

Now, the fun part . . . . installing the speaker.  This is a large speaker compared to Soundtraxx ones I've used.  I needed a place to mount it, and found the space in the radiator wings to be the perfect place for this.  Some small modifications were made, like a new cross brace to hold the speaker somewhat in place.  I also added two narrow strips of plastic along the insides of the rad cover.  This was to snug the speaker in place and prevent side to side movement.  I could have used some clear silicon caulk to mount it more permanently, and will do so later, once I buy a set of the Miniatronics male/female plugs, so I can disconnect the speaker from the decoder when performing maintenance.   But for now, this works perfectly.   The speaker is aimed downward, so the sound is projected over the gear tower and rear truck.

This worked fine, but on some sections of track, I noted a slight reverberation on the rails.  I took the foam paper Athearn uses in their blue box locos, cut a small strip, pressed it inside the rad top, then snapped it back in place.  Perfect!!  The sound is crisp and has the fidelity I'd expect.  The bell still sounds too electronic, but is OK.  All sounds were reset using LocoBuffer-II, which I use for all my programming. The only CV I have had trouble with is CV155.  I wanted to set the ramping effect to manual, rather than letting the decoder decide this.  As it is, the sound starts up when the throttle is turned up and seems to stay at a set rate.  Very little ramping can be detected as speed is increased.  I tried different settings on the Notching setting, but nothing happened. Still, I am reasonably impressed with this decoders' sound.  I know the AC4400 has a different prime mover than the Dash 9, but it's acceptable for now.  One thing I do wish is Digitrax providing a bit more explanation about the various CV's and what they are/used for.  Many mean nothing to me, making setting some CV's more of a mystery than they should be.

I might also add that when I wrote Digitrax about some settings on the Tower 55 AC4400, I got a reply that the decoder is "like" their DH163, meaning it really isn't (and it really isn't!!).  I was told later versions would be easier to program, and that this is not two decoders, but rather one, with the function piece added.  Kind of cheesy, if you'd ask me.

Jim Oliver

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