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[BaBaLou.]

A grounding plane does or does not matter the form, shape or size as in the case of the tripod antenna or the WGL antenna when using the 9.5 length of antenna?

For one setup, the CM15A Mod is the same as dave w

Using a coax cable stripped at the end to 9.5"/no grounding plane=20' range one directions mainly.

When adding a grounding plane=20'range but all direction.

Then I stripped it up to 18" of exposed coax cable and with or without a grounding plane=Range of remotes and sensors shot up to to 40'+ in most directions. The area is inside
an office building with metal stud walls and that does add a little to the challenge to my business setup.

I did add a passive reflector to DS10A and an Eagle eye just to give me that little bit more of reliability of the setup.

[Brian H]

Thanks for sharing your findings.

[accord728]

Another option (easier one than moding your CM15a) you may have is to use the SR731-S Smart RF Repeater with the Wireless Transceiver (TM751, which stated in an earlier post). I use all that equipment with my CM15a device and I have no problems with RF signal. Also, playing around with a location with these devices can help significantly. I hope this helps some.

[HA Dave]

Then I stripped it up to 18" of exposed coax cable and with or without a grounding plane=Range of remotes and sensors shot up to to 40'+ in most directions.

That report is enough to get me to try the extra length.

[PajamaGuy]

That report is enough to get me to try the extra length.

Me too!

Has anyone found differences in coax?  RG-6/UQ?, RG-59? - etc?

[HA Dave]

Has anyone found differences in coax?  RG-6/UQ?, RG-59? - etc?

You may want to do some searching on that. My memory says the 75-Ohm cables are better because the RG-59 can cause some sort of reflective interference. However... a quick search didn't confirm my gray-matter reference.

[Alan V]

Has anyone found differences in coax?  RG-6/UQ?, RG-59? - etc?

You may want to do some searching on that. My memory says the 75-Ohm cables are better because the RG-59 can cause some sort of reflective interference. However... a quick search didn't confirm my gray-matter reference.

If you're using an F-connector then you'll want to use RG-59 cable (which is 75 ohm and well matched to the F-connector).  RG-58 cable is 50 ohm.

[Puck]

The frontend receiver of the CM15A is 50 Ohms. 1/4 wavelength antennas (single vertical element referenced to a ground plane) are generally ~50 Ohms as well. For optimal signal transfer between the 2, the cable impedance should be the same. Most people have 75 Ohm cable handy (or easier to get) because it is what most all cable companies use. It is not the best for optimal efficiency, but it will work better than no mod to the CM15A. If you have a very long cable run, I'd recommend keeping the impedance matched.

[PajamaGuy]

http://en.wikipedia.org/wiki/Coaxial_cable

Thanks! - It's a short run, and to maximize WAF, it has to be white - I think I have both RG-6 (what the DirecTv guys use now) and some RG-58 (what they used to use)  Any suggestions on testing/detecting for RF interference from PCs, printers, TVs, or other office equipment?

I know it's weird, but if I hook a 20' cable to my modded CM15a and leave the antenna mounted on the wall, if I then move the CM15a around the room, in certain areas it will NOT receive RF.

[jsnone1]

The frontend receiver of the CM15A is 50 Ohms. 1/4 wavelength antennas (single vertical element referenced to a ground plane) are generally ~50 Ohms as well. For optimal signal transfer between the 2, the cable impedance should be the same. Most people have 75 Ohm cable handy (or easier to get) because it is what most all cable companies use. It is not the best for optimal efficiency, but it will work better than no mod to the CM15A. If you have a very long cable run, I'd recommend keeping the impedance matched.

so will there be any issues using the RG58-50 Ohm with the  F-connector?

[Puck]

so will there be any issues using the RG58-50 Ohm with the  F-connector?

There are F-connectors made for various cable sizes, including RG58.

[HA Dave]

I know it's weird, but if I hook a 20' cable to my modded CM15a and leave the antenna mounted on the wall, if I then move the CM15a around the room, in certain areas it will NOT receive RF.

That doesn't sound right... except for maybe a kink in the 20' cable... location should I would think... be indifferent.

[Brian H]

At the 310 MHz X10 uses. The difference between RG59U and the RG6U/QS [QS quad shielded] would not make much difference. The RG6U/Q quad shielded stuff is rated in the multi GHz. range and is use in things like Digital Cable TV and Satellite Dish stuff.

I would double check your coax if moving it around to some places kills the reception. maybe the center conductor is shorted to the shield. That braided stuff only needs one barely visible strand to touch the wrong thing to make a short.