Any swivel base telescoping antenna mast would work, as long as the length is the correct size, or multiples of the frequency.
Well, I answered my own question. I called X10 and was told they don't support replacement parts, including antenna masts. From their point of view, I had 3 options: If under warranty, send back the unit, if under extended warranty, send back the unit, and they would send back a new one. Third option was to buy a new unit. What BS.
I went to radio shack and got a replacement mast # 270-1404, 28". I needed to use my dremel tool to grind down the thickness of the knuckle. The original knuckle thickness was 0.040, and the one from Radio Shack was 0.070".
Five minutes with my dremel and a micrometer and the knuckle was the correct thickness. One could probably do this with a hand file, would take a bit longer...the knuckle is fairly soft metal. Since the DS7000 mast is about 11.5 inches long, I set the new mast to 23" and it works very well. Seems to pick up sensors from a greater distance.
There are various electronic stores (All-Tronics, Jameco, Mouser, etc.) that have telescoping masts that were much closer to the original length, a bit cheaper than RS, but I didn't want to wait. I think the cost of the Radio Shack mast was $4.
I can't see any reason why a similar fix would not apply to any x10 device with an antenna. For the ones that transmit, it would be optimal if the length of the antenna was the same, or multiples of the original (this allows for best wave propogation from the antenna.)
-John
