Wire Gauge for Ground Plane?

Hi Mario,
Yes, I've heard of using the adhesive aluminum tape to cover over the existing metal strip that is placed under the engine cab that increases the size of the antenna. Does it do any good and/or increase the antenna reception? Good question for someone like Dale to explain-he's the expert here.

The locomotive I have the least problems with regarding signal reception is a die cast tender. The entire shell is the antenna. It was also a pain in the * to set up. The shell has to "float" off the frame (I used black electrical tape to make a gasket) and I had to find nylon screws of the appropriate diameter and threading to mount the shell to the frame.

If you read through the link on the garden railroading site I posted earlier in this thread there are locomotives that have had their internal antennas lengthened to 8 feet to get good reception on an outdoor layout that uses trackside "telephone" poles carrying the ground reference plane.

The biggest issue with TMCC is the receivers need to be able to detect the ground reference plane in order for the system to work. In a properly wired house and a properly installed system the house wiring can help as the ground wires in the walls become part of the system. When you add auxiliary ground wires or extend an antenna you are trying to enhance the ability of the receiver to discriminate the signal from other noise (aka to detect the ground plane). There is plenty of track signal, often times too much. There isn't a "halo", its more like a fog/soup. The signal can interact with any ungrounded metal objects that can act as induced antennas. You can either try to identify these objects and then try to ground them OR you can establish "local" ground planes near the track to provide the receivers with the needed reference points.

quote:

Originally posted by chuck:
The locomotive I have the least problems with regarding signal reception is a die cast tender. The entire shell is the antenna. It was also a pain in the * to set up. The shell has to "float" off the frame (I used black electrical tape to make a gasket) and I had to find nylon screws of the appropriate diameter and threading to mount the shell to the frame.

I converted a couple of MTH steamers to TMCC from PS/1, and I was pleased to find that they used standard 6x32 screws for the tender, not the oddball sizes that Lionel uses! I also use Kapton tape to insulate the tender, it's very thin, but very strong. It's easier to work with and more reliable than black electrical tape for the job.

David, if you look at the pictures of my layout at www.manquen.net, you will note that I definitely have vertical clearance problems. I had to notch my roof rafters to avoid knocking horns off of diesels!

BTW, I DO have an 8' steel whip antenna in the garage...

quote:

Originally posted by Dale Manquen:
David, if you look at the pictures of my layout at www.manquen.net, you will note that I definitely have vertical clearance problems. I had to notch my roof rafters to avoid knocking horns off of diesels!

BTW, I DO have an 8' steel whip antenna in the garage...

Dale I would figure everyone with few exceptions would have some clearance problems from one of those.I remember my dad had one on the car and there was a big scratch on the inside of the garage door where it had rubbed it each time he went in and out

Now we hit a cell tower miles away with a little antenna that will fit on your thumb

Times have changed WOW

David

Now is the signal from the PowerMaster to track AM. FM. SSB, CW, Packet.....?

Quarter wave for a cell fone is light years shorter han the freq used for TMCC>

A Powermaster doesn't talk to the track. It only varies the AC voltage to the track.

The track signal and the CAB-1 signal are both FM using FSK.

Hi Guys this is a little off topic, but it shows how a thread like this can help find a problem. If you read one of my past post above I stated that I was having some AM reception problems on a car radio I have rigged up in my train room.
Well after reading all the above about fresnels, noise, ect I got to thinking that maybe there was something in the house causing my trouble and there was.

At first I thought that it might be one of the 10 base T signal units that I am using but they checked out OK. Then I remembered the deck lamp on the back deck tripped it's GFI a few weeks ago so I tried that and the gfi trip again and my AM reception cleared up.
I checked the switch and inside outlet the first time it tripped and it looked good, I figured my wife just hit the switch with wet hands or something like that, wrong! Of course I tried the lamp a few times and it worked.

This time I took the deck lamp apart and an outlet I had installed for a deicer cable they put on the down spout. That is another long story about no sun under the deck causing an ice jam, but I digress.

When I took the housing for the out let apart I found a ground wire that the electrician wraped around the proper ground screw but forgot to clip off. That pig-tail has found it's way over to a unused copper screw on the outlet that was never wraped with tape and was just barely touching.

The funny part was that the breaker tripped when the light was turned on but the noise was there all the time. Well to bring this story to it's conclusion a half hour of trouble shooting got my rear deck light working and my AM noise cleared up.

quote:

Originally posted by gg1man:
Hi Guys this is a little off topic, but it shows how a thread like this can help find a problem. If you read one of my past post above I stated that I was having some AM reception problems on a car radio I have rigged up in my train room.
Well after reading all the above about fresnels, noise, ect I got to thinking that maybe there was something in the house causing my trouble and there was.

At first I thought that it might be one of the 10 base T signal units that I am using but they checked out OK. Then I remembered the deck lamp on the back deck tripped it's GFI a few weeks ago so I tried that and the gfi trip again and my AM reception cleared up.
I checked the switch and inside outlet the first time it tripped and it looked good, I figured my wife just hit the switch with wet hands or something like that, wrong! Of course I tried the lamp a few times and it worked.

This time I took the deck lamp apart and an outlet I had installed for a deicer cable they put on the down spout. That is another long story about no sun under the deck causing an ice jam, but I digress.

When I took the housing for the out let apart I found a ground wire that the electrician wraped around the proper ground screw but forgot to clip off. That pig-tail has found it's way over to a unused copper screw on the outlet that was never wraped with tape and was just barely touching.

The funny part was that the breaker tripped when the light was turned on but the noise was there all the time. Well to bring this story to it's conclusion a half hour of trouble shooting got my rear deck light working and my AM noise cleared up.

Mario,

THATS NOT OFF TOPIC!!!!!!!

It is exactly what I'm trying to tell you guys . You don't seem to understand the significants of the bad ballast in the florescent fixture or the arching screw.This causes noise and the noise kills the signal.
To not give this the credence it deserves is the same as not plugging your transformer in and wondering why your trains don't work ,it's just that important.

I know it's a major headache to find and believe me Mario did get lucky.
The AM radio is the best sniffer.

The older the wiring the more likely you'll have problems but with a lot of investigating it can be resolved.
If you haven't checked around your layout with the AM radio there's no use saying my trains don't work and your just wasting your time.

David

Meanwhile, back on the layout, more fun 'n games -

I tried again just now with "ole run-away". Seems the problem, or at least one problem, is pushing the front coupler button causes a loss of signal connect. Nothing works after that. I know that because even the horn won't work after hitting "F". But, hit "10" reset and then the horn works again and it will move out. But just better not touch that front coupler. Anyone ever seen that before?

And the bonus is, I have a second engine doing the same thing (I think they must talk to each other or something).

So we try still another engine I haven't run in a while. Did fine for a few minutes. Then it blew its horn on its own. Then its rear coupler cut lose and it left its train behind. Then when I stopped it, it refused to honor the shutdown command. Just plain weird, except the headlight flickered a bit on that one.

Good news is, a fourth one did pretty good. But slow responding to speed up and slow down commands. They don't all take the same amount of turning of the BRK.

..it's hard to pretend you're watching a real engine on that favorite prototype road, while holding the Cab-1 in one hand and keeping the other hand near that transformer handle and anxiously wondering what's next...but all just a typical day..

quote:

Originally posted by Ginsaw:
the base is plugged into its own power strip

Ginsaw, have you tried plugging the Command Base's 3-prong wall wart directly into a wall outlet? I've personally seen lots of unexplainable behaviors with TMCC locos that were magically cured when the power strip was bypassed.

Is it a K-line loco that takes off after the coupler button is pressed? I've seen that happen and always with K-Line. It is some kind of problem with the coupler coil and replacing the coupler fixed it.

quote:

Originally posted by DPC:

quote:

Originally posted by gg1man:
Hi Guys this is a little off topic, but it shows how a thread like this can help find a problem. If you read one of my past post above I stated that I was having some AM reception problems on a car radio I have rigged up in my train room.
Well after reading all the above about fresnels, noise, ect I got to thinking that maybe there was something in the house causing my trouble and there was.

At first I thought that it might be one of the 10 base T signal units that I am using but they checked out OK. Then I remembered the deck lamp on the back deck tripped it's GFI a few weeks ago so I tried that and the gfi trip again and my AM reception cleared up.
I checked the switch and inside outlet the first time it tripped and it looked good, I figured my wife just hit the switch with wet hands or something like that, wrong! Of course I tried the lamp a few times and it worked.

This time I took the deck lamp apart and an outlet I had installed for a deicer cable they put on the down spout. That is another long story about no sun under the deck causing an ice jam, but I digress.

When I took the housing for the out let apart I found a ground wire that the electrician wraped around the proper ground screw but forgot to clip off. That pig-tail has found it's way over to a unused copper screw on the outlet that was never wraped with tape and was just barely touching.

The funny part was that the breaker tripped when the light was turned on but the noise was there all the time. Well to bring this story to it's conclusion a half hour of trouble shooting got my rear deck light working and my AM noise cleared up.

Mario,

THATS NOT OFF TOPIC!!!!!!!

It is exactly what I'm trying to tell you guys . You don't seem to understand the significants of the bad ballast in the florescent fixture or the arching screw.This causes noise and the noise kills the signal.
To not give this the credence it deserves is the same as not plugging your transformer in and wondering why your trains don't work ,it's just that important.

I know it's a major headache to find and believe me Mario did get lucky.
The AM radio is the best sniffer.

The older the wiring the more likely you'll have problems but with a lot of investigating it can be resolved.
If you haven't checked around your layout with the AM radio there's no use saying my trains don't work and your just wasting your time.

David

Hi David, I know it's not off topic but I wonted to avoid the usual cascade of conflicting opinions that follow any declaritive staetment on such subjects.
That said, the clue I spoke off in my above post was the AM radio acting as my sniffer as you described. In any case if not for the back and forth information flow here I don't know how long it would of been before I saw that obvious clue glaring me in the face. So again I say thanks and hope all has learned something. I know I picked up a new trouble shooting tool for TMCC, that is something I never had before.

When we were laying the track, nobody had heard of "ground plane" or the need for it with TMCC.

quote:

Originally posted by Bob W / cprail:
Thanks, gunrunnerjohn and trains41.

RE: the aluminum tape, I wish I'd thought of it when I was laying track several years ago. How did you attach it to the ground wire?

quote:

Originally posted by gg1man:

quote:

Originally posted by DPC:

quote:

Originally posted by gg1man:
Hi Guys this is a little off topic, but it shows how a thread like this can help find a problem. If you read one of my past post above I stated that I was having some AM reception problems on a car radio I have rigged up in my train room.
Well after reading all the above about fresnels, noise, ect I got to thinking that maybe there was something in the house causing my trouble and there was.

At first I thought that it might be one of the 10 base T signal units that I am using but they checked out OK. Then I remembered the deck lamp on the back deck tripped it's GFI a few weeks ago so I tried that and the gfi trip again and my AM reception cleared up.
I checked the switch and inside outlet the first time it tripped and it looked good, I figured my wife just hit the switch with wet hands or something like that, wrong! Of course I tried the lamp a few times and it worked.

This time I took the deck lamp apart and an outlet I had installed for a deicer cable they put on the down spout. That is another long story about no sun under the deck causing an ice jam, but I digress.

When I took the housing for the out let apart I found a ground wire that the electrician wraped around the proper ground screw but forgot to clip off. That pig-tail has found it's way over to a unused copper screw on the outlet that was never wraped with tape and was just barely touching.

The funny part was that the breaker tripped when the light was turned on but the noise was there all the time. Well to bring this story to it's conclusion a half hour of trouble shooting got my rear deck light working and my AM noise cleared up.

Mario,

THATS NOT OFF TOPIC!!!!!!!

It is exactly what I'm trying to tell you guys . You don't seem to understand the significants of the bad ballast in the florescent fixture or the arching screw.This causes noise and the noise kills the signal.
To not give this the credence it deserves is the same as not plugging your transformer in and wondering why your trains don't work ,it's just that important.

I know it's a major headache to find and believe me Mario did get lucky.
The AM radio is the best sniffer.

The older the wiring the more likely you'll have problems but with a lot of investigating it can be resolved.
If you haven't checked around your layout with the AM radio there's no use saying my trains don't work and your just wasting your time.

David

Hi David, I know it's not off topic but I wonted to avoid the usual cascade of conflicting opinions that follow any declaritive staetment on such subjects.
That said, the clue I spoke off in my above post was the AM radio acting as my sniffer as you described. In any case if not for the back and forth information flow here I don't know how long it would of been before I saw that obvious clue glaring me in the face. So again I say thanks and hope all has learned something. I know I picked up a new trouble shooting tool for TMCC, that is something I never had before.

Mario,
I think Dale hit it on the head when we talked about the confusing technical jargon.I told Ben and Jim about the AM radio when we had the other thread going and NJHR was having trouble but I don't think that most folks really understand that just like anything else to set up command control certain things have to be done to make it reliable.

Ben and Jims problem is unique in that they are in an old building with old equipment and 3 phase equipment at that.

If you want to take on the task of running ground wire under the layout to retrofit it you can .I would still where possible/practical run my wire at 90 degree angles to the track so if you have a rectangular shaped layout you want the wire to run from left to right parallel with the short end you can use small 22 gauge wire and run it in an "S" pattern I know thats not always possible.

You can attach it by stapling it to the under side and you should make every effort to make sure it's in between the track and any hot or powered wires you have under the table.

Oh and the foil tape can be attached to the ground wire by doubling the ground wire several times and wrapping the foil around it then use a small radiator hose clamp to hold it together just make sure you use some corrosion inhibitor

Because the copper will eat the thin aluminum

Good Luck everybody

David

quote:

I would still where possible/practical run my wire at 90 degree angles to the track

Do you have a good reason for recommending this? Most of the previous posters with problems due to too many parallel tracks, overhead tracks or nearby metal attached to the outer rail have found that running a wire parallel to the track works just fine. Some use trackside power poles to hold the wire.

A wood screw through the aluminum tape with flat washers on either side of the wire wrapped around the screw will work just fine. There is no significant galvanic corrosion on a clean, dry interface between galvanized steel washers and aluminum.

quote:

Originally posted by Dale Manquen:

quote:

I would still where possible/practical run my wire at 90 degree angles to the track

Do you have a good reason for recommending this? Most of the previous posters with problems due to too many parallel tracks, overhead tracks or nearby metal attached to the outer rail have found that running a wire parallel to the track works just fine. Some use trackside power poles to hold the wire.

A wood screw through the aluminum tape with flat washers on either side of the wire wrapped around the screw will work just fine. There is no significant galvanic corrosion on a clean, dry interface between galvanized steel washers and aluminum.

The flat washer will work just as good as the hose clamp but the very thin aluminum will be eaten by the copper causing a loose connection coupled with the vibration of the train table. It's just good practice to use corrosion inhibitor when joining soft copper and aluminum because they are dissimilar metals .A lot of you guys call it contact grease and it's not hard to come by.

I can only say that the recommendation to run the wire at 90 degrees to the track is an educated hunch .Anytime you run wires parallel to each other you run a chance of inducing an unwanted current in the wire and if that wire is a resonant wave length of something you don't want you have it running right there under the whole length of your track.
If the wire is run at 90 degree angles this is not likely to happen.

David

quote:

I can only say that the recommendation to run the wire at 90 degrees to the track is an educated hunch .Anytime you run wires parallel to each other you run a chance of inducing an unwanted current in the wire and if that wire is a resonant wave length of something you don't want you have it running right there under the whole length of your track.

David, how many times do I need to remind you that with a wavelength of almost half a mile, there aren't any tuned lengths or resonances for the TMCC track signal? A crosswise wire will only benefit the area where the wire crosses the track, whereas a wire along the track will benefit the entire length of the wire.

Bob Bartizek, I just saw your post. Yes, I have tried in the past, but not recently, plugging the CB directly to the wall socket instead of into a computer strip. It was an experiment to correct the electronic problems. It changed nothing. I also tried temporarily wiring together the outside rails of my Ross track. That also changed nothing. I tried some other things too, but at the moment don't remember what they were.

taylorra, I would love to know what brand of diesel that was.

Dale, you said "problems due to too many parallel tracks". Can you expand on that?

Btw, the practical problems I've described are far from an exclusive list. Just one more - I have two identical engines with an identical issue. It's like this - I have modern electronic Controllers that run parallel loops interconnected with switches but electrically isolated at the switches in the usual way. One Controller is a New ZW w/ 180 bricks. The other is the ZWC w/ 135 bricks (earliest variant of the New ZW).

So, what's going on? Well, these engines run fine off the New ZW in all respects. And they run fine off the ZWC excepting one thing. When you hit the DIR button on the Cab-1 they do a slow staggering slow speed stutter step in reverse. They will stop on command and when you hit DIR again they reverse direction and perform normally going the opposite way. But you can forget changing directions.

And, I've already tried reversing which Controller goes with which loop. That proved nothing.

quote:

Dale, you said "problems due to too many parallel tracks". Can you expand on that?

The TMCC signal to the locomotives consists of two components. One is the track-conducted signal from the Base U terminal; the other is the airborne "earth ground" signal that radiates from the house wiring. The radio receiver in the locomotive senses the difference between these two components, much like connecting these signals to opposite ends of a wire and then measuring the resulting current flowing in the wire. (This is exactly what the loco's radio does, using the chip to "measure" the difference.)

If we have overhead track, trackside metal structures or screen tunnels connected to track Common, overhead catenary wiring or too many parallel tracks (multiple mainlines or complex yards), we have too much of the track Common signal, and this squeezes out the airborne "earth ground" signal.

The solution is to restore the balance by adding in some "earth ground" signal with wires adjacent to the track. In a yard situation, small-gauge magnet wire running parallel between every two or three tracks will do the job. Connect the wire to earth ground, the U-ground pin of a wall outlet receptacle, or pin 5 of the 9-pin serial connector. One Forum member recently solved his problem by connecting his non-functional catenary to earth ground.

Is this explanation adequate?

OK, wrong thing. Wat does the Command Base send to the track: AM. FM. SSB. Packet, CW.......?

Dominic, I already answered your question on Page 2.
Both the CAB-1 and the Command Base output FM with FSK data.

quote:

If we have...or too many parallel tracks (multiple mainlines or complex yards), we have too much of the track Common signal, and this squeezes out the airborne "earth ground" signal.

What I have are three parallel mainlines, a reversing loop, an engine ready track on the side plus two yards, one with a four way. All get the same tmcc signal.

Among other things, I gather this rules out trying to connect together the outside rails (I use Ross track with wood ties) to further enhance the signal. This is something I once tried as a temporary experiment and it didn't help engine performance. I guess I know why now.

Like I said, there's no close-by water pipe and there's the lack of earth ground to the wall socket plug. When we discussed that earlier, I recall it was said here that's not a problem and that it's enough to run the CB to that socket even though it goes nowhere.

So, apparently, that leaves two options. One, put in the ground wiring beside tracks, and two, add more antenna to certain engines. Is that what this amounts to?

All of which assumes that the various problems are not a matter of defective engine boards.

I think that adding some wires connected to Pin 5 would be your best bet.

I did that with my tmcc as an experiment. I'm normally connected with the third wire to the house ground. But, I have a wire under the layout that goes around the perimeter of the layout connected to pin 5 as well. And just to see how well it works using that and without a house ground connection I isolated the ground pin of the power to the layout. It all works well. The layout is about 12 by 16 or so.
Just saying...

I think the principle problem for many of us has been the complete lack of knowledge about radio theory. Track power is something we easily understand. But, just the mention of ground planes has us thinking, well, I've got two choices. Hope that someone knowledgeable here explains it well enough to get a grasp on the subject, or, do what we prefer not to do, and that's go in for a whole bunch of research.

Now that won't help your trains run any better, but it might help explain where many of us are coming from, or maybe even be a starting point...

Earth ground should be easier to use assuming the house is wired properly. If it's not, then you start having problems. You need a reference point for the signal to be perceived. Pin 5 on the command base is tied to the ground prong on the power supply. That would normally get you access to earth ground and use all of the ground wires in the house for signal reference purposes. By isolating that connection and using pin 5 on the command base you've turned the system into a two wire system. It doesn't use earth ground, it uses the signal ground of the command base.

I think the term "ground plane" is part of the problem. If it were called the safety wire in your house wiring, that might not raise so many unfamiliar feelings.

This ground thing came up before. I did ask MFJ if their artificial ground would work with the TMCC signal. It only works to 160M for ground.

Notice above, I ran my system perfectly without any connection to the house safety wire (which is incidentally eventually connected to earth). I used instead a separate wire which runs under the layout around the perimeter of the 12 by 16 table and is connected to pin #5 of the base serial connector.

quote:

Originally posted by chuck:
Earth ground should be easier to use assuming the house is wired properly. If it's not, then you start having problems. You need a reference point for the signal to be perceived. Pin 5 on the command base is tied to the ground prong on the power supply. That would normally get you access to earth ground and use all of the ground wires in the house for signal reference purposes. By isolating that connection and using pin 5 on the command base you've turned the system into a two wire system. It doesn't use earth ground, it uses the signal ground of the command base.

Nice post Chuck,(Seriously)

I want to touch on a scenario that happens more often than you think.A lot of houses over the years in various parts of the U.S. use a water pipe ground.It does what it's designed to do but what has happened is that while the pipes in the house haven't been changed the line to the street and the line in the street have- with plastic.


Couple this with an aging infrastructure of most power companys distribution network (Power lines) it's easy to see that if you have that water pipe ground it may be time to consider putting in a ground rod or two.

I was called numerous times by the Roanoke City Water Dept. because an employee got the daylights knocked out of him while trying to change the water meter.

This was because the connection between the pole and the house had broken on the neutral.If you've got a good house ground changing the meter isn't a problem but if you don't not only does the worker get the crap knocked out of him but it can and will burn up every thing on one 120V leg in the house Why?

It's simple. All the things in your home that use electricity need a return path or ground to work.Thats why you have a plug with 2 prongs, one is hot and one is the neutral.In your home you have 220V this is done by running 2- 120V lines and a Neutral to the house from the transformer at the pole .We branch off of those 2 lines for lights and receptacles and use the 220 for water heaters ,stoves, heat pumps and dryers.

Now if we loose that return path it will cause an imbalance. The voltage will radically spike up on one side while dropping on the other side.So on one side you could have 200V and 20V on the other side. If that happens you just lost every piece of electrical equipment on the 200V side that uses 120V .Light bulbs will pop circuit boards will fry and I've been to a good many house fires because of it.
Not to mention the water dept. guys getting their wristwatch battery recharged

If you have a house built prior to 1970 I strongly urge you to drive a ground rod .The new National Electric code requirements call for 2 ground rods

In any event if you see the lights in your home get really bright in some rooms and really dim in others run don't walk to the panel, turn off the main breaker and call the power company.

David

The common use of the term "ground plane" here is not referring to the house wiring, but rather to additional conductors added to the layout to enhance the distribution of the signal from Pin 5.

One of the confusions here is that neither the track Common nor the Pin 5 "ground" are really zero volts reference points. Both of these points have necessary parts of the TMCC signal on them.

Suppose you've got an engine that blows its horn by itself intermittently at a given place on your layout, or a coupler opens by itself at the same spot, but nowhere else. What in tmcc's world would be the most likely cause?

Would adding a #5 pin ground plane be the likely fix, or, are other causes just as possible?

First, we would need to know if the coupler problem is an electrical problem or the very common "weak spring" syndrome.

Second, does the troublesome area have any of the known hazards - overhead tracks, nearby metal connected to track common, multiple parallel tracks, etc.?

I don't have any direct experience myself with that type of problem, but it is so easy to drape a temporary grounded wire such as a 3-wire extension cord next to the trouble area that I would try that test first.

A marginal signal may lead to "confused" signals reaching the microprocessor. The bit patterns for some errors may be more likely than others.

I doubt there's anything wrong with the coupler and the horn does it at the same spot. There are three mainlines and interconnecting switches there. But they're present elsewhere too. No overhead tracks. There are metal block signals and a metal radio tower, but they have a separate power supply and aren't involved with track power.

I wonder if dirty track could do it. It's on the far side and doesn't get cleaned as much as it should. Although other engines don't do that.

I don't know how this really works, but two things occur to me. One, is an errant outside signal that mimics a tmcc signal. Two, is what you said, a marginal signal that causes confusion.

One other thing, tmcc doesn't operate in the frequency range of cell phones and cordless phones, does it? And how about the presence under the layout of an old AM/FM/SW radio w/ external and internal antenna? Could such a thing be a problem even if not turned on, despite being plugged into the power strip with the CB??

quote:

Originally posted by Ginsaw:
I doubt there's anything wrong with the coupler and the horn does it at the same spot. There are three mainlines and interconnecting switches there. But they're present elsewhere too. No overhead tracks. There are metal block signals and a metal radio tower, but they have a separate power supply and aren't involved with track power.

I wonder if dirty track could do it. It's on the far side and doesn't get cleaned as much as it should. Although other engines don't do that.

I don't know how this really works, but two things occur to me. One, is an errant outside signal that mimics a tmcc signal. Two, is what you said, a marginal signal that causes confusion.

One other thing, tmcc doesn't operate in the frequency range of cell phones and cordless phones, does it? And how about the presence under the layout of an old AM/FM/SW radio w/ external and internal antenna? Could such a thing be a problem even if not turned on??

Dirty track is too often not taken seriously enough. I.E. There was a few page "ground plane" article written in OGR by another forum member which was very informative. After installing ground planes in the problem areas, there were still some with signal issues which were later resolved by a good track cleaning. Sometimes you don't realize how dirty it is until you clean it. I normally scrub it with Lionels abrasive eraser and the wipe it off with alcohol.

quote:

There are metal block signals and a metal radio tower, but they have a separate power supply and aren't involved with track power.

Any large metal objects that are not connected to earth ground can act as secondary signal sources. The main signal is quite capable of being regenerated in nearby metal objects. These secondary signal sources can interfere with the receiver's ability to detect the reference plane. You can test this out using the test cable outlined in previous posts. If this works you may need to install a reference source or tie the offending objects to earth ground (assuming you can actually identify the secondary source).

Do not rule out dirty track. If you have the "wrong" pattern embedded in the track crude you might be generating spurious signals from the arcing caused by the crud.

I just verified that a locomotive in Command mode will not respond to the manual whistle/horn DC offset.

The radio will not bother the TMCC if it is not turned on. I did recently find that my AM radio in the kitchen, mounted above eye level, can pick up a noise caused by the TMCC track signal in the floor of the attic just above the radio - maybe 2' vertical spacing. This seems to be a new problem.

The TMCC track signals are at a much lower frequency than any wireless home appliance.

quote:

will not respond to the manual whistle/horn DC offset.

It's not the DC offset that seems to be causing the problems. It's almost like the noise pattern mimics a command. It seems to be most likely with the horn/whistle. It usually affects a single loco and only occurs at very specific locations on the layout. It is often direction dependent (aka the effect will happen traveling left to right but not right to left). Sometimes cleaning tracks/wheels will clear it up. Very high on the weirdometer.

quote:

There are metal block signals and a metal radio tower, but they have a separate power supply and aren't involved with track power.

Does the wiring for these devices run under the table in close proximity to your track power wires?

Is that accessory power supply completely isolated from any track contact at any operating accessories or insulated track sections. Many of the accessories have a grounded metal chassis, such as the horse and cattle corrals.