Re: J&M CB
I have the J&M CB too (model JMCB2003-SL). The one with the J&M logo on it...not the BMW(OEM) radio...which is also made by J&M. Anyway, I'm using it with the BMW CB antenna that's made for the LT...only I changed the whip.
I've had some issues (see my previous threads in this forum about it) with squealing, and noise. I was able to solve the squealing problem by installing a longer whip, and then tuning (i.e. cutting) the antenna whip until I achieved the optimum SWR readings (must have an SWR meter to do this).
Te noise problem however, I have not been so successful with, and have simply learned to live with it. The noise is coming from the power supply on the bike. I do have the J&M noise filter installed (doesn't help), and I've even tried installing a ground loop isolator, and moving wires around to position them as far away from the batt/alternator as possible...but all of that was of no help. The only time I can make ignition/alternator noise go away, is to disconnect the J&M CB from my Beahr Intercomm system. So....I just live with it. I ride with ear plugs, so it's not really that noticeable.
The system itself works fine. I use it often when riding in groups to communicate to the others, and it's been quite handy to have when I'm cruising the super slab (to hear about traffic back-ups, wrecks, etc). Doing so has saved me from some rather lengthy Chicagoland traffic back-ups by hearing of them well ahead of time..and being able to exit early and take an alternate route.
The $750 price you're quoting must be for the BMW CB? I only paid about $250 for my model JMCB2003-SL.
I wish I could think of clever things to say in my signature.