Really strange problem / fix

[Dean]

I just installed a new LM-3 into a new Stewart/Kato F7. The install went fine. But during testing, my HC kept losing contact with the LM-3. The engine never hiccuped, the loss of radio signal could happen anywhere on my layout. It even dropped out when I was standing less than 2' away from the engine. ( imagine if you can a fat, bald old guy trying to chase down a run-a-way engine    )
I checked the install and found nothing wrong. After an hour of checking and testing the only thing I could think of was where the LM-3 was installed. It was pressed down against the two wires coming from the rear truck. ( they were covered with shrink tubing ) I postulated that the LM-3 was getting radio interference from the AC track voltage that DCC uses. I taped a thin piece of lead to the bottom of the LM-3 and reinstalled it. Problem solved. The engine ran for over an hour without any problems.
Strange, really strange.

Dean

[Alan]

Doesn't surprise me. There is no difference between a wire and an antenna. Twisting the wires may eliminate the problem in the future.

The LM2 has a RF shield built in. Your problem may be a consequence of the shield being dropped from the LM3.

[Dean]

Thanks for the information. I was wondering why I didn't have any problems with installing LM-2s in identical engines.

[KPack]

I had no idea the RF shield was dropped from the LM-3.  Did Tim determine that it wasn't necessary or was he looking for more space?

-Kevin

[Alan]

I don't own any LM3, LM3S or LM2S. My fleet is solely LM2. Basing on Tim's earlier comment.

Interesting, the LM-2S's (and 3S's) I have don't have what looks like a shield over the RF circuit board as Alans does. Wonder why it was dispensed with?

Perhaps Alan can chime in, I wonder if the temp sensing works properly without the unit be contained in the case?

- Tim

[Dean]

Thanks for all the replies and information. I will remove the lead and use aluminum foil.

Dean

[Alan]

What's wrong with the lead. Adds weight. That's generally a good thing.

[G8B4Life]

Indeed, the LM-2S's and 3S's I have don't have the shield.


LM2-S no shield.

The omission surely can't be a manufacturing error as it carried over from old product to new product.

- Tim

[TwinStar]

This might explain a problem I had almost three years ago. I had a LM-2S equipped unit pushing a flat car that had a GoPro Hero 3+ on it live streaming the feed to my phone. When the GoPro was streaming the LM-2S was unresponsive. I hadn't thought about that until now.

[Dean]

The lead is thick enough that it makes the LM-3 stick up above the frame. I would like to keep it below the frame to ensure the body fits right.
I am going to try to get some pictures.

[Raconn]

Hi all, I am imminently purchasing Railpro and hope to be able to install the module in my Stewart F7s and F3s. Since this thread referenced that type of locomotive, can anyone tell me how the install went and especially if the module size and/or speaker size presented any challenges. If so how were they overcome? Photos would be helpful too.  Thank you.

[Dean]

My Stewarts are the older model that was made by Kato. I believe they went out of production in the mid-1990s.
I have no experience with the new ones.

[Raconn]

Hi Dean, The older Stewarts are what I have.  I'm re-entering the hobby after years of things being in storage while I moved around for my career.  I'm retired now.  All of my Stewart F7 and F3 fleet is original Stewart/Kato. It all runs great but is purely DC.  I've collected trains for 50 years and never had a serious layout but am building one now.  I am wiring for DC and Railpro because it isn't practical to convert everything but my favorites are the Kato, Stewart, Atlas and a couple of Proto 2000 types.  Any info or photos you could provide would be appreciated.  Mostly you've answered the most important question I had which is will it fit into the Stewart F7.

[Dean]

I'll work on getting some pictures, I hope.