"Double" Soft Key Commands

I also put in a plastic fiber pin on the center rail

I assume that you mean that you no longer have a two complete loops, correct? Rather, each loop is now, in effect, a block with two ends.

Some questions:

• Is there any chance that the problem occurs when the engine is straddling both sides of the center rail insulating pin?
• Does the problem occur on both loops or only on one?
• Does the problem occur with one engine or more than one engine?
• What track and transformer are you using?

A variety of causes have been posted, including having 2 feeds per block.  I don't have 2 feeds to any block, but get this in 2 of my 70 blocks.  Problem occurs with many different locos on my layout, but only in these 2 blocks..

Barry: Both loops are totally isolated. I would say it occurs more frequently on the larger outside loop vs smaller inside loop. Only one fiber pin is in place on each loop so yes technically the center rail has two ends. 

In regards to your questions:

1) No. Occurs in various spots near and far to fiber pin

2) Both loops but I notice it more on the larger (outer) loop. 

3) More than one engine but some engines are more likely to repeat commands than others

4) Transformers are Z1Ks and track is Lionel 0-27 profile tubular track. Outside loop has no switches, inner has 3 Ross switches. 

RJR - Only one feed on each loop with one fiber pin essentially cutting the continuous loop of track/center rail. 

How are you powering the TIU and which TIU channels are you using?

The 1Ks are hooked to the Fixed 1 and 2 channels via those MTH barrel adapter doo-dads. 

Clean the wheels and rollers.  

I just got bit by that when I was testing a TIU.  When things went south, I looked at the TIU, the track, the wiring, and then realized that the rollers had a track of black goo on them!  Cleaned it up and suddenly everything worked properly.

I'm not sure how many times I have to learn that lesson.

GRJ, that may not be it.  Just got a new PS3 loco today, and is does this all over the layout.  Of course, there may be some glop on the rollers.

John, 

Been there done that...no change. I've had the double command thing on my old layout and that was my "clean the track" message...did so and no problems for a few weeks/months. Strangely enough, that doesn't fix anything here. 

RJR - I have another PS3 engine coming in later this week/early next week. I'd be curious to see what happens. I've noticed that it occurs in roughly the same spots  but on various intervals. Checked those spots for signal strength and power with a multimeter and no obvious issues. I only have one fiber pin on the center rail, was thinking what doing the same to the outer rails would result ing.....strange....(no operational issues, just occasional double whistle/commands in roughly the same spots). 

That certainly sounds like a signal reflection, perhaps some of the DCS filters might help?

John,

 perhaps some of the DCS filters might help?

Although possible, it's unlikely, since he has a Rev. L TIU.

Thanks for the filter tips John/Barry. 

Would you both agree, since there are no operational issues other than the occasional double command, that there really isn't anything to worry about? 

Would you both agree, since there are no operational issues other than the occasional double command, that there really isn't anything to worry about? 

Yes.

If it doesn't bother you, I agree with Barry, it's not going to hurt anything.

Now I'm going to shoot all the theories. 

My new PS3 Decapod does double whistles everywhere on the layout.  Ran a PS2 Northern right behind it and, hitting the whistle button in the same places, never got a double.

So it must be something in the locos, maybe in combination with the track.

I have had this problem for a long time, and I found a great solution, stop caring! My trains have worked fine ever since this solution If the whistle blows twice, it does. BUT, that is just how I feel about it now. 

Cleartrack,but using SXS makes for a lot of whistling.  I didn't mind it when it only happened in one block, but a single loco doing it all over the layout is too much.

Oh yeah, no doubt that would bother me. happening only in one block, I let it go. I started a thread about it some time ago. I had continued to search but it seems still there is no real solution.  

Every "solution" presented to me for this has resulted in no success of making the problem go away.

Where is the feed in relation to the block length? One thing that sometimes happens in DCC is "bounce-back" from the end of the block. Snubbers (filters) placed at one end of the block, with the feed at the other seems to stop this. This might be happening here as the distance between the feed and the end of the block could be just right to have reflection occurring.

Matt, if 24 locos have no problem and one does, I'm not about to rewire.