CM15A antenna mod

Can you tell us what your system's comprised of? Number and type of modules? Have you installed a coupler/repeater?? Are you having problems with other devices?

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Connectors aren't your problem - BNCs are not a problem until above UHF. 310mhz is below that so BNCs or even PL259s are OK. I'd focus on the coax to address loss. Try to keep the feedline as short as possible. Here is a site which will help you determine how much loss your particular coax.

would think you'd want 50-ohm coax so be sure you're not using cable-TV or other 75 ohm line. Investing in some low-loss cable would help for sure. I'd go with a halfwave dipole for good omnidirectional performance and make sure it matches the polarization of your receiver, IE if the receiver's antenna is vertical, then so should be the TX antenna to avoid any polarization penalty. If a halfwave dipole isn't cutting it, then build a gain antenna like a 5/8 wave. It won't be too large at 300MHZ.

I'd also think about improving the RX antenna. With X10 I've improved my reception just by using clipping a lead on the antenna to provide some more length.

Let us know your results! Thanks, Corey J. Anderson

right now my system is pretty basic. CM15A with a couple of switches. I've added the motion detector and chime, but the lack of range on the motion detector is what got me started on the antenna mod to get better range. Going to adjust the cable length next...

Now I'm thinking I'll have to get an inline amplifier.

You might have an easier solution.. Why not get get a Xm10 receiver (I don't have the part number at hand) for about $20, and plug it in near the motion sensor?

No antenna mod, etc, just different scripts on the cm15a...