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[steven r]

...What is the gray wire for that wraps around the top of the battery carrying cover for the CM15A?  It ties to a second daughter board about an inch away from the one the antenna ties in to....

Is that the internal antenna for RF transmission from the CM15A?
(The external one is just for receiving.)

[JeffVolp]

A question for the technically more proficient than I:  What is the gray wire for that wraps around the top of the battery carrying cover for the CM15A?  It ties to a second daughter board about an inch away from the one the antenna ties in to.  Is it some kind of ground plane for the external antenna?

The CM15A contains both a RF receiver and a RF transmitter on separate daughter boards.  The gray wire looks like the transmitting antenna.

Jeff

[Brian H]

Yes the Grey wire is the Transmit Boards Antenna and in all the ones I have seen. Glued to the case.

[BillB3857]

Makes good sense that it would be a "Transmit" antenna.   That saves the cost of a TR switch.  Since my system only uses the receive function, I never gave it a thought that the unit would need to be able to send info via RF also.  If I expand my system so that the transmit function is used, would it benefit from an antenna mod similar to the receive function?

[Brian H]

I am not sure about the transmit antenna. I believe the transmit board is not very sophisticated and may even have the antenna as part of the tuned circuits. I will look at the schematics and see what I can find.

[HA Dave]

...... I never gave it a thought that the unit would need to be able to send info via RF also.  If I expand my system so that the transmit function is used, would it benefit from an antenna mod similar to the receive function?

I use BVC to Voice Command for most of my X10 setup. The CM15A (and HA Computer) are in the basement. I have modified the CM15A with a TM751 antenna recently... I had originally just soldered on a a 9 1/4 inch wire.

When I decided to put a Ninja mounted camera in the backyard and voice command it (with the RF coming from the CM15A in the basement).... I needed more Umph. I performed the antenna mod on the Ninja (adding a TM751 antenna to the ninja). And merely pried loose the CM15A's internal transmit antenna... drilled a hole and exposed the gray wire to the outside... where it now just hangs.

Hanging the gray-wire outside the CM15A's case.... make a world of difference.

[BillB3857]

Thanks for the responses!  This forum is GREAT!

[ejmiami]

Thanks for the great instructions and pictures.   I did the mod with the exact supplies suggested by the poster -- but don't know how successful it really was.   It does seem to pick up the front door sensor about 20' away more reliably than before, however an extra door sensor I tested just couldn't be "heard" by the CM15A through the walls of my kitchen in the center of the house in my old 1500 sq ft Florida ranch.      I did have two problems  1) the first #10 washer I bought at a local hardware store was too thick to fit - I ended up making a special trip to the Home Depot and their #10 washer worked  2) I had a terrible time getting the stripped wire end to stick to the antenna base with super glue.  It had to let it set overnight and I am still not sure it is working as well as the poster's mod. I am almost tempted to use the alternate connection from the TM571 with the foil.  Overall though great idea and nice looking result.

[Brian H]

#2 Maybe the problem. If the glue is insulating the wire from the metal antenna. The range may not be much better.
Also Motion Sensor range is controlled very much by distance and what is between it and the receiver. Metal can decrease the range.

[HA Dave]

If the glue is insulating the wire from the metal antenna.

I soldered the wire on my antenna mod... and I think that does help. But getting the new antenna (and the CM15A) up higher... can make a big difference also.

[aslamma]

Have not been around for a while and was curious to see how everyone was doing with this.  Been working great for me, I am close to (if not) 100% reliable after this mod.  Glad to hear it works well for others and I have always been a perfectionist and wanted it to look nice as well.

[cantbreak80]

Hey...Noob here, so I'm a little late in the game.

But, I just wanted to tell you how good this mod works...it works real good!

And, I wanted to share how I attached the white wire to the TM571 antenna base...I soldered it.

To get the base to accept solder, I used 80 grit sandpaper to "scrub" the nickel/chrome finish off.  There's brass-colored metal beneath that shiney
finish and once it's gone it doesn't take much iron heat to get the antenna wire soldered to the base.  I used my old soldering pencil with it's nearly worn-out 30 year old tip to get the job done.

My remotes now work from the street...approx 75' from the CM15A!

[TCruz]

I just received my AHP kit 2 days ago and I was very disappointed in the coverage the cm15a "had". I was trying to use an old transceiver with it to just to get coverage to other end of my house but that was causing other devices to turn and off along with the ones I was wanting to control. I found this thread and decided to give it a shot. Best thing ever! X10 should just use the antennas they use on the tm751's. I now get signal from all corners of the house with just the cm15a; upstairs and downstairs. I did change it a bit though. Actually much easier way. Instead of a washer I used a ring terminal instead. Cut the wire out of the old antenna and crimped it into the ring terminal. Nice and tight fit with metal to metal contact, and no soldiering or gluing required; a real 10 minute job. I will be doing this to my brothers tomorrow.

[Brian H]

The new version of the TM751 has the Same Receiver Board in it as the CM15A.
The new TM751 beats the unmodified CM15A by a long shot. Shows what a better antenna can do.

[aslamma]

Tcruz, I like your idea (as well as the one as cantbreak80) for improvments.  Can you upload a picture or two?