Rocket_Cowboy Posted March 8, 2007 Share Posted March 8, 2007 Maybe this isn't specific to hexheads or RTs, but surely someone has figured this out by now. I've got an Autocom installed on my RT, and have pretty well worked out all the kinks for the components I wanted installed. Next task to tackle ... CB radio. I know BMW relabels the J&M system, and that the BMW kit provides a splitter so that the factory am/fm radio antenna can also be used for CB. I already have a 4' Firestik NGP antenna, cabling, etc., so my preference would be to make that work if possible. My problem ... on previous bikes, I've been able to find existing bolts on the rear of the bike that I could incorporate into my antenna bracket mount. I'm just not seeing anything on the rear of the RT that looks like it lends itself to using some longer bolts and spacers, in order to get a bracket attached. How have others fabricated brackets for rear mounted CB antennas? Any good pics or tips for the R12RT? Heck ... maybe even the K12GT would offer some ideas. Link to comment
Buckster Posted March 8, 2007 Share Posted March 8, 2007 Check the rearmost bolts that go into the trunk rack. They go upward (from behind the tail/brake light housing) into the rack. By using a metal bar of less than a 1/4" thick, I believe you could extend outward to either side and mount the antenna. This could be past the edge of any trunk and above the saddlebags. The determining factor will be the twisting motion of the mounted antenna on the bar. I would suggest either angle iron or maybe C channel but I would try to keep the thickness to a minimum to keep from pushing the rack up. You might have to shim up the front bolts (just under the back edge of the rear seat) to avoid torquing the plastic of the rack too much. Buckster Link to comment
Rob Posted March 8, 2007 Share Posted March 8, 2007 buckster, do you have a photo of the setup. I'm working on the same project for the GT and RT. Thnaks, Link to comment
decorbin Posted March 8, 2007 Share Posted March 8, 2007 I had the same problem before getting rid of my R12RT. I don't think the material of the rack is strong enough to hold much more. I ended up using a half-wave UHF antenna attached to the top case so it did not require a ground plane. That won't work for a CB obivously, because the antenna would be too long. Another option might be the mount where the antenna for the AM/FM radio goes if you don't have one of those installed. You might also ask someone who has seen the RT authority bikes. Perhaps the antenna mount from one of those would work. Link to comment
Mudman Posted March 8, 2007 Share Posted March 8, 2007 Charlie, I think I have just what you have been looking for. I will take a couple of pictures and post again. I used a bar mounted to the rear rack. The two bolts it uses were longer than stock so the bar did not touch the plastic below. This has proven to be a reliable mount for over 13000 miles of touring and works with or without the large rear trunk. I'm out to get photos Link to comment
Mudman Posted March 8, 2007 Share Posted March 8, 2007 I don't have a web site so I will PM you with the photos Link to comment
dawn Posted March 8, 2007 Share Posted March 8, 2007 Hey I really appreciate you getting all this figured out for me. I'll just sit back and watch. I bet a search on other posts from you will answer a bunch of questions. It is tough planning when you don't even have the bike yet. Only 2 more sleeps! Link to comment
Rob Posted March 8, 2007 Share Posted March 8, 2007 Mudman, could you send me a copy of the pic's also? My email is lessen1@ckt.net Thanks, Link to comment
Rocket_Cowboy Posted March 9, 2007 Author Share Posted March 9, 2007 Mudman ... PM sent. Thanks again! Link to comment
Rocket_Cowboy Posted March 9, 2007 Author Share Posted March 9, 2007 Hey I really appreciate you getting all this figured out for me. I'll just sit back and watch. I bet a search on other posts from you will answer a bunch of questions. It is tough planning when you don't even have the bike yet. Only 2 more sleeps! I'm going to take off all my goodies when you come to test sit my Elf Pegs. Just kidding! I had tried doing a search before, but think "CB" is too short a search term, and didn't get much help searching for antenna. Link to comment
RideTN Posted March 9, 2007 Share Posted March 9, 2007 hey rocketcowboy how is your rt working out? you got an opinion on the vibration issue i was reading about recently on this forum? Link to comment
Scarver Posted March 9, 2007 Share Posted March 9, 2007 Charlie has seen my set-up but others may also be interested in this solution to the problem. The antenna mount was constructed from 1/4 X 2 inch aluminum stock. Used band saw to cut rough outline and then used a lot of elbow grease to shape and polish it. Ham radio with APRS and GMRS radios are working fine. Have not yet tuned CB antenna. Picture was taken before installing switch box that allows selection of specific radio on which to transmit. Autocom PTT switch controls transmission. Link to comment
Mudman Posted March 9, 2007 Share Posted March 9, 2007 Very nice job I have enough trouble getting one radio working Link to comment
Rocket_Cowboy Posted March 9, 2007 Author Share Posted March 9, 2007 how is your rt working out? you got an opinion on the vibration issue i was reading about recently on this forum? I must have missed the vibration issue, got a link? The RT vibrates a good bit at idle, but once moving she's smooths right out. I'm convinced that she's getting smoother all the time the more I ride. I've only got just over 1700 miles on her so far, but no vibration related problems for me that the 600 mile service didn't cure. Link to comment
ernie_v Posted March 9, 2007 Share Posted March 9, 2007 On my 02 RT I used a piece of 3/16 x 1 aluminum flat stock bolted to my GIVI mounting plate. The flat stock stuck out the right side enough so the 3' Firestik cleared the top box. I am transferring the same pieces to my 06 RT. I will use longer bolts in the two rear locations on the GIVI bracket, or use two seperate bolts. Strength was not an issue on the 02 RT. I am using an 8' long NGP coax from Firestik. Do they make a shorter cable so I don't have to wrap the excess all around nder the seats? Link to comment
RideTN Posted March 9, 2007 Share Posted March 9, 2007 hey rocket, here is the link. http://bmwsporttouring.com/ubbthreads/showflat.php/Cat/0/Number/802801/an/0/page/1#Post802801 Link to comment
Rocket_Cowboy Posted March 10, 2007 Author Share Posted March 10, 2007 I am using an 8' long NGP coax from Firestik. Do they make a shorter cable so I don't have to wrap the excess all around nder the seats? I've got the same length of cable for my NGP Firestik. My understanding is that since the antenna has no ground plane, the length of the cable is critical in getting the antenna to act efficiently. Link to comment
Rocket_Cowboy Posted March 10, 2007 Author Share Posted March 10, 2007 hey rocket, here is the link. http://bmwsporttouring.com/ubbthreads/showflat.php/Cat/0/Number/802801/an/0/page/1#Post802801 My experience with the RT so far ... while there was some buzziness in the bars right around 4100rpm initially, the 600 mile service cured that problem. Not sure if it was a throttle body sync, or the head retorque, but no more buzz int he bars on mine. Link to comment
Buckster Posted March 10, 2007 Share Posted March 10, 2007 Sorry no photo as I have not made a bracket myself. I have taken the rack off several times and looks that this would work... Link to comment
RockyGlide Posted March 11, 2007 Share Posted March 11, 2007 Hi Mudman, I'm also looking at installing my Firestik NGP antenna. Would you be so kind as to email the pics as well to harold.foth@gmail.com ? Thanks Link to comment
Mudman Posted March 12, 2007 Share Posted March 12, 2007 I will get the pictures e-mailed to you in a couple minutes Link to comment
RockyGlide Posted March 12, 2007 Share Posted March 12, 2007 Hi Mudman, Thanks for the pictures, information & tips. You did a good job on the mount. Link to comment
dawn Posted April 13, 2007 Share Posted April 13, 2007 Hey Mudman, I finally got my J&M Mounting bracket and am in serious need of guidance for my antenna. Think I could get your pics e-mailed to me as well? dpenning@gmail.com Thanks Link to comment
Mudman Posted April 13, 2007 Share Posted April 13, 2007 Hi Dawn, E-mail and Photos sent. Good Luck Link to comment
CraCol Posted April 16, 2007 Share Posted April 16, 2007 Scarver, What exactly is a "Slim Jim" GMRS antenna and it benifits? Is it an available part or a home made item? Thanks, Craig Link to comment
SageRider Posted April 16, 2007 Share Posted April 16, 2007 My antenna mount on my R1200-RT: Bracket fabbed by Sean Daly as a one off design. 11 degree side to side slope milled into part of bar which attaches to rack to level bracket in the side to side horizontal plane. 13 degree angle in bracket to position antenna without interfering with Trunk latching mechanism. 5 degree front to rear slope milled into antenna pad to level bracket in the front to rear horizontal plane. Link to comment
Scarver Posted April 17, 2007 Share Posted April 17, 2007 Craig, An English colleague mentioned that the Slim Jim antenna design was popular a few years back. A Google search quickly pointed to articles where 2M antennas were made from the old 300 ohm flat TV cable. That is what I used to build mine. However, you can buy a similar antenna from Autocom (Part U141) for $75. The benefit of this type design is that the measured SWR is around 1.7 - 2.1 versus the 3.89 for the rubber ducky. That simple change boosted power output from the Kenwood TK3101 radio from the rated/published 2 watts to 3 watts (measured.) It is also flexible and easy to mount on your bike. Charlie (Rocket_Cowboy) has his Autocom antenna Velcroed to the inside of his windshield. Link to comment
CraCol Posted April 17, 2007 Share Posted April 17, 2007 Thanks for the reply... GMRS works well, but range is sometimes an issue.. Craig Link to comment
Rocket_Cowboy Posted April 17, 2007 Author Share Posted April 17, 2007 I'll post up pictures of my install after I get back from the Cape Fear 1000. Since I'm not planning on running GMRS for the rally (I'll be riding solo, so there's no one to talk to), I pulled it off for the weekend. Once I get back, I'll revert the setup back and snap some pics. I've been real happy with the 3101 matched up with the remote antenna. As Herman said, we measured the new antenna a couple different ways, and in all cases it improved performance of the radio with the remote antenna over the rubber ducky. Link to comment
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