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[medic5678]

i started experimenting with ahp and the cm19a, just seeing how it worked.  turns out the cm19a has only 10 feet or so reliable range...  and that's if it didn't have to work through a wall.  i found the antenna hack stuff online, and i all i can say is *wow*.  it works *fabulously* well, at up to 100 feet!

i made the 1/4 ground wave ground plane antenna shown in this page:  http://marc.merlins.org/perso/linux/post_2011-07-24_Hacking-an-external-antenna-onto-an-X10-CM19a_-and-adding-misterhouse-support.html

antenna instructions here: http://cocoontech.com/forums/topic/126-how-to-build-an-antenna-for-your-x-10-receiver/

cost about 40 bucks including the cable to make it.   i am picking up a cm15a in the near future, and i'm making one for it as well.  the antenna is ugly, but hey... so am i! .

[dave w]

 

[spval]

I did the same thing. Actually, I just added a pig tail with a male F connector and then experimented with the antenna length. I don't use rf commands, but I noticed that the rf range was pretty good when I tried a rf command. My CM11A and CM19A combo work as well as the CM15A (which is connected now). You can buy a new CM19A on ebay for $ 20.00 shipped.
-spval

[gg4000]

I made one with some old external linksys antenna. What's the best way to test the distance?

[spval]

If you want to check the distance for "receiving" rf signals, you would need a rf sensor or rf window/door relay sensor that you can move around to different positions in the house or yard. At some point you will no longer be able to receive the signal, as indicated by AHP or some similar type program. Once the signal no longer registers, you could try different antenna lengths at the CM19A end and see if you can get the rf signal back. If you want to check the abilty of the CM19A sending rf range, you would need something like a TM751A transceiver. In this case, keep moving the TM751A around the area and see when it gets out of range of the CM19A. Again, experiment with the length of the antenna to find out what is the best configuration for your environment. Also, experiment with the vertical and horizontal layout of the antenna.
-spval

[medic5678]

[spval]

That's a great looking ground plane antenna !

-spval

[medic5678]

i have put my antenna outside and also put a passive repeater on my motion senser (this is just a piece of 19.5 inch coat hanger wire fastened to the side of the sensor).  my range is now at around 225 feet!   so if the system is armed and someone hops my gate, it will get tripped.   still playing with it but i am very, very happy with this range .

[dhouston]

You'll be extremely unhappy if lightning hits it.

[dave w]

You'll be extremely unhappy if lightning hits it.

Well, the CM19A would make a worthly lightning arrestor if the ground trace on PC board is ran the earth ground. 

[medic5678]

i'll also be unhappy if i get in a car wreck the next time i drive.   that doesn't keep me from driving .

[Brian H]

Actually the CM19A Schematic shows the ground as being the USB Common.
Your computer will be the ground point.

[dhouston]

While this was written for TV antennas, it applies to any outdoor antenna.

• http://www.dennysantennaservice.com/1171010.html
• http://www.antennahub.com/grounding-tv-antennas.aspx

[medic5678]

ok, so let's say it fries my motherboard and my cm19a.   let's say it costs me $200 to fix it.  how often is this likely to happen?  once in 50 years?  in the long run, it really won't matter .  in the meantime, i have a system with excellent range.

[dhouston]

ok, so let's say it fries my motherboard and my cm19a.   let's say it costs me $200 to fix it.  how often is this likely to happen?  once in 50 years?  in the long run, it really won't matter .  in the meantime, i have a system with excellent range.

It will only happen once, leaving a pile of smoldering ashes and maybe bones behind as a warning to others who see no need to add lightning protection to outdoor antennas. Why do you think the NEC and most local laws require it?