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Author Topic: CM15A Antenna mod...yeah, another one  (Read 16648 times)

bkenobi

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CM15A Antenna mod...yeah, another one
« on: February 15, 2011, 11:24:19 PM »

I was originally going to try one of the mods using the Radio Shack antennas that have been listed here, but couldn't find a bolt, washer, or screw that would fit in my stash.  Rather than run out to the store and buy a bunch of stuff to try, I decided to just perform the F connector mod that has been written about so many times.  I seriously appreciate the write ups as performing the mod took no time with the knowledge I gleaned from everyone else.   >!

Ok, so here's the part where I did my own thing that others might be interested in.  I was planning on installing an outdoor scanner antenna I picked up from Radio Shack (20-176) in the attic.  But, before going through that effort, I wanted to make sure I didn't fry the CM15A first.  I didn't have any other F-connector antenna lying around, so I decided to make one real quick and dirty.  The funny thing is, it works GREAT!  I've doubled or tripled my range with a palm pad remote.  All I did was take an old coax cable that had one end broken and stripped down to the copper core all but the very end where the good connector was.  I then cut the core to 18.5" from the end of the shielding.  I used a 90 connector to get the antenna pointing the right direction.

Before any mods I was lucky to get 15' through 1 wall.  After this mod I have been able to go ~50-60' through 4 walls.  I don't plan this to be my final antenna, but I wanted to let people know how easy it can be to build one from scratch.

dave w

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Re: CM15A Antenna mod...yeah, another one
« Reply #1 on: February 16, 2011, 11:03:59 AM »

You made yourself a nice 1/2 wave antenna. I use a 1/2 wave up in the attic by just stripping coax shield away from the last 18 inches of a junk piece of RG6. The other end laced down through ceiling is connected to "F" connector modded CM15A.

It works very well even though I did everything wrong ( the active element should have been a 1/4 wave with ground plane rather than 1/2 wave, receiver input impedance is ~ 50 ohms, so should have used BNC connector and RG58 coax, and should have kept total coax length in whole increments of one wave length) but it works well enough for my application and like you I did not have BNCs and RG58 in the junk box.

This thread is rich with info on the CM15A mod and antennas:
http://forums.x10.com/index.php?topic=9470.90
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bkenobi

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Re: CM15A Antenna mod...yeah, another one
« Reply #2 on: February 16, 2011, 01:17:15 PM »

Yup, that's one of the many threads I read.  I'm sure people have been using this type of cobbled together antenna before, I just hadn't seen anything in the threads.  I thought about going full wave, but decided that would be too long for RG6 to support itself vertically and I also read that full wave was bad for certain things.  I'm no RF expert, though.

Anyway, I'll probably install the Radio Shack antenna after I get all of my hardware setup in the right locations.  I was just shocked that this cheapo setup worked as well as it does!

xboxhaxorz

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Re: CM15A Antenna mod...yeah, another one
« Reply #3 on: March 09, 2011, 12:43:47 AM »

i bought the antenna you mentioned 20-176
http://www.radioshack.com/product/index.jsp?productId=2103641

but it uses pl 259, and i put the f connector on my cm15. they didnt have any connectors that were pl 259 to f.

this antenna looked as though it would do the job, but i guess i have to get something else that uses f connector

the thing is not all shack antennas tell you the mhz. this antenna specifically said it was within 100 to 1300mhz
« Last Edit: March 09, 2011, 12:47:18 AM by xboxhaxorz »
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bkenobi

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Re: CM15A Antenna mod...yeah, another one
« Reply #4 on: March 09, 2011, 01:14:11 AM »

Yeah, I just got the F-PL259 adapter and connected it to the antenna.  I actually have an old radio antenna wire running up to the attic as well (with PL259 already on both ends), but I decided to use the RG6 instead since it's run to the office next to the CM15A.

FWIW, I've found a couple dead spots with this setup that are in unfortunate locations.  The biggest one is in the hot tub.  The lights all turn off at 11pm automatically, so I bring a palm pad with me so I can turn them back on.  The problem is that I have to reach to an awkward position to get it to work.  I may supplement with a TM751...

Dan Lawrence

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Re: CM15A Antenna mod...yeah, another one
« Reply #5 on: March 09, 2011, 12:58:20 PM »

Yeah, I just got the F-PL259 adapter and connected it to the antenna.  I actually have an old radio antenna wire running up to the attic as well (with PL259 already on both ends), but I decided to use the RG6 instead since it's run to the office next to the CM15A.

FWIW, I've found a couple dead spots with this setup that are in unfortunate locations.  The biggest one is in the hot tub.  The lights all turn off at 11pm automatically, so I bring a palm pad with me so I can turn them back on.  The problem is that I have to reach to an awkward position to get it to work.  I may supplement with a TM751...

You should change the time the lights go off to 12:00 midnight (or later) so they won't go off while you are in the hot tub.  Easier than that "reach to an awkward position "
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Noam

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Re: CM15A Antenna mod...yeah, another one
« Reply #6 on: March 09, 2011, 01:24:43 PM »

You should change the time the lights go off to 12:00 midnight (or later) so they won't go off while you are in the hot tub.  Easier than that "reach to an awkward position "

Alternatively, you could set a second "off" time for midnight, and change the 11pm shutoff to a conditional macro.
Set a flag (or turn on a real or dummy module) before getting in the hot tub, and have the condition test for it. If you are in the hot tub, let it leave the lights on.
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bkenobi

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Re: CM15A Antenna mod...yeah, another one
« Reply #7 on: March 09, 2011, 05:07:39 PM »

I was thinking about how to implement a dummy module like that.  I guess I could use a different keychain remote to activate a dummy that then keeps certain lights on.  I'd probably want to have a second timer also (as suggested) to turn off the lights at 12 (or some other time later than that) as a catch-all to make sure I didn't forget to turn them (or the dummy module) off.

Good input...THANKS!

lviper

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Re: CM15A Antenna mod...yeah, another one
« Reply #8 on: March 11, 2011, 05:17:53 PM »

You could use a ds10a wired to the lid. When the lid is opened the ds10a is opened. When the ds10a is opened it can set the flag leaving the light on till you close the lid.
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bkenobi

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Re: CM15A Antenna mod...yeah, another one
« Reply #9 on: March 11, 2011, 06:11:07 PM »

Funny...that was my original thought.  I was thinking I could put the magnet side on one side of the lid and the transmitter side on the other (away from the house).  The thing I wasn't sure of was whether the DS10A transmits it's status when the contacts are open or just on a state change.  I have several sitting in a box but haven't had a chance to play yet.

I tried a KR19A the other day and found out just how bad the range is on those things.  I could use a palm remote, but I'd probably have to get a second one just for a single on/off button.  Actually, I saw a dial that you could add to any x10 device that makes it easy to change house/unit code.  Can't remember where I saw it so I can't buy any now, though.

Brian H

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Re: CM15A Antenna mod...yeah, another one
« Reply #10 on: March 11, 2011, 06:16:30 PM »

http://www.smarthome.com/4824B/X10-Code-Clickers-10-pack-Black/p.aspx
http://www.smarthome.com/4824R/X10-Code-Clickers-10-pack-Red/p.aspx

Also I have seem some say the thick plastic cover over the house code dial and key labels. Gets in the way
I believe someone glued a plain washer on one of theirs.

There are probably other vendors that have them and Smarthome's shipping manytimes is a killer.

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bkenobi

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Re: CM15A Antenna mod...yeah, another one
« Reply #11 on: March 12, 2011, 11:18:11 AM »

Interesting that red is much more expensive than black.  Are these for the small style rotary switches (like on the older light modules) or for the current larger style (like on the palm pad and current lights)?  Probably not worth getting these since I can probably come up with a cheaper/better solution without shipping, but I definitely appreciate the links!

EDIT:  Ooops, I just saw there is a dimension listed.  Thanks again!
« Last Edit: March 12, 2011, 11:19:50 AM by bkenobi »
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bkenobi

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Re: CM15A Antenna mod...yeah, another one
« Reply #12 on: November 22, 2011, 04:39:35 PM »

This is an update to include my final setup as well as some experience along the way...


With the baseline CM15A, I was able to use the palm pad remote from around a room away (maybe 30 ft through 1 or 2 walls).  That does not work in my home let alone the motion sensors outside!  So, the first thing I did was to modded the CM15A to add an F-connector and a new antenna.  I started with the following setup:

CM15A (f-connector modded) -> RG6 coax whip antenna (18" stripped to the center core).

With this setup, I found that I could get signals from much farther and showed that the antenna could make a dramatic difference to the receiving performance of the CM15A beyond baseline.  My next step was to try a better antenna.  Enter the Radioshack 20-176.

CM15A (f-connector modded) -> 6ft RG6 coax -> Coax-to-SO239 adapter -> Antenna (RS 20-176)

I located this setup in my office as before and was VERY pleased to find that I could now use the palm pad remote from anywhere on my 5 acre property.  After testing for a few days, I decided to install the antenna in the attic similar to what bcondemi did in his home (http://forums.x10.com/index.php?topic=12292.0).  My run was as follows:

CM15A (f-connector modded) -> 3ft RG6 coax -> gold 90 connector -> Wall plate (zinc? coupler) -> RG6 coax to basement structured media box -> gold coupler -> RG6 coax to attic -> Coax-to-SO239 adapter -> Antenna (RS 20-176)

With this setup, I could get better coverage than the original antenna, but I certainly lost some range.  I had other projects going on, so this one sat this way for several months.  When I saw dave w's post (http://forums.x10.com/index.php?topic=25109.0) around 1 or 2 months back, it made me start thinking about this again since I need to get the rest of my motion sensors set up.  I purchased an in-line amp from Radio Shack (15-369) and installed it as follows:

CM15A (f-connector modded) -> amplifier power inserter -> 3ft RG6 coax -> gold 90 connector -> Wall plate (zinc? coupler) -> RG6 coax to basement structured media box -> gold coupler -> RG6 coax to attic -> in-line amp -> Coax-to-SO239 adapter -> Antenna (RS 20-176)

With this setup, I could get access to all of my house and quite a ways away from the house with the palm pad.  I though I was done!  Well, when I started playing with the keychain remote and the MS16A motion sensors, I found that I get spotty coverage where I need them.  So, I added a passive 18" whip to 2 and a 9" whip to the other.  With this setup I get reliable coverage from the specific locations I tried.  BUT, now I would have long wires hanging from these units which would dramatically reduce the all important WAF.

So, I purchased a second in-line amp from ebay.  There are lots of them out there, but I chose the one with the attached picture.  It's a wide frequency amp that works with DBS, cable, radio, TV, etc.  Since I already have a power injector from the RS unit, this one is all that's needed provided that it's located on the correct side of the power filter from the RS inline amp.  Anyway, here's my final setup:

CM15A (f-connector modded) -> amplifier power inserter -> 3ft RG6 coax -> gold 90 connector -> Wall plate (zinc? coupler) -> RG6 coax to basement structured media box -> in-line amp (ebay) -> RG6 coax to attic -> in-line amp (RS) -> Coax-to-SO239 adapter -> Antenna (RS 20-176)

With this setup, I can now remove the whips from the motion sensors and the keychain remote can be received from ~200ft!  Now, I've only had this setup since last night, but so far, so good!  Granted, this is not the easiest setup and certainly costs more than the stock CM15A on its own.  BUT, it works much better.  I suspect that if I had just gotten the V572 (http://www.wgldesigns.com/v572.html), I would have been pretty close to the same performance.  I just couldn't justify spending that kind of money for something that I couldn't try out and return if it failed.  This setup is all available from RS locally (well, except for the extra amp which was only $6 on ebay).

Oh, one thing that's worth mentioning I suppose.  If I had a power filter that was separate from the inline amp, I probably could have simply replaced the RS and ebay amps.  The RS is rated at 10dB gain whereas the one from ebay is 30dB.
« Last Edit: November 22, 2011, 04:42:19 PM by bkenobi »
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bkenobi

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Re: CM15A Antenna mod...yeah, another one
« Reply #13 on: July 01, 2014, 07:27:43 PM »

Old thread, but since I'm looking at the same setup, it seemed appropriate to keep it to a single thread.

I have modified my installation in a HA server change but I hoped to see a RF reliability improvement.  I moved my HA server from AHP on a Windows XP machine in my office to a Raspberry Pi running HomeGenie that is located at my structured media panel.  The old installation seemed to provide relatively reliable service for RF, but it struggled when the weather got cold and wet (half the year in Seattle).  In summer, I get on the order of 90-95% reliability from MS16A + passive antennas.  In the winter, I get closer to 25%.  The setup is best described in the attached pictures.

In essence, I removed around 20' of coax and several connection points.  I'm finding that I don't get great coverage even in the locations that worked well before.  Could shorter wire cause issues that I'm not thinking of?  What else could I try?

bkenobi

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Re: CM15A Antenna mod...yeah, another one
« Reply #14 on: July 01, 2014, 10:39:06 PM »

Problem solved.  Apparently I didn't have things exactly like the schematic nor identical to my old setup (less wire).  The ebay filter seems to work only if its on the antenna side of the power injector.  Also, I may have had it reversed (not sure, but probably).  I don't recall my maximum range before, but I can now use a palm remote (HR12A) anywhere on my t acres that I've tried (outside).  I'll have to verify inside, but if I can reach 200-400ft through air and walls, I should be able to reach most places inside.
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