CB PTT squeal - how was it solved?

[IdahoMtnSpyder]

I've been reading threads till my eyes are bleary, but I don't find the answer. I read many threads about problems SL members had with their BRP CB causing a squeal when they pushed the PTT to transmit. This problem apparently reared its ugly head with the advent of the 2014 RT. Well, I've got the same problem with my 2014 RTS with a 2015 model of the BRP CB and driver headset harness that I bought from a fellow SL member. I used the entertainment harness and antenna and coax from my 2013. I never had a squeal problem with the 2013 RT.

The usual causes of such problems are, and my situation with regard to them are as follows.

A squeal can be result of a high SWR (standing wave ratio) so that's where I started checking. My system is showing an SWR over 3. It needs to be less than 2.

High SWR can be caused by a bad ground. Ohmmeter check shows I have good continuity to ground from the coax shield.

A shorted coax will cause the problem. Ohmmeter check shows I have no short in the coax.

A broken center conductor will cause a problem. There is good continuity from one end to the other of the coax so it's not broken.

A smashed or bent coax will cause a problem. I bought a new coax. It did not improve the situation.

A broken wire in the antenna will cause problems. An ohmmeter check of the antenna shows full conductivity from the bottom to the top.

An inadequate ground plane will cause a high SWR. I wheeled a 2' x 3' steel table next to the bike and connected the coax ground to it. Voila! The SWR dropped to about 1.5! Oh :cus:! The squeal still occurs. Obviously it must not be caused by a high SWR. There must be a common root cause for both the squeal and high SWR.

Induced signals in the headset harnesses can cause feedback. Disconnecting the driver headset harness from the entertainment harness did not solve the problem.

Acoustic feedback from the helmet speakers to the helmet mike will cause feedback. The squeal still occurs even when the headset is unplugged. I hear it in the handheld I'm using for testing so the squeal is being transmitted and not just limited to the bike helmet headset.

Have parts been updated that could be the answer? The radio has been updated, and the one I got is the latest version. The antenna, coax, and mounting block are the same part numbers as five years ago. The newer entertainment harness wiring configuration is the same as the old one I have.

My question is to everyone who had a squeal problem with your CB. Did you get the squeal squelched? If so, do you know what the technical fix was that solved the problem? I read several threads where the dealer changed out all the components but the squeal remained. So it must be caused by some interaction between the CB and some aspect of the bike that is not an integral part of the CB.

Has anyone successfully used a Non-Ground-Plane antenna? You have to use an NGP coax or it won't work. Not doing so may have been the reason a couple of users reported an NGP antenna didn't work for them.

I installed the CB myself and have done all the trouble shooting myself. My dealer has almost no experience with CBs and since I bought the CB in a private sale BRP won't lend a hand. The dealer did give me a copy of the installation instructions. They're almost identical to the one from five years ago. Plus, the dealers mostly just swapped out parts for most of the SL members who had this problem, and mostly that didn't help much. I'll send an inquiry to BRP and see if I can get an answer from them, but I'm hoping someone who got theirs fixed knows what the fix was.

 

[ThreeWheels]

I had the squeal in my 2010 RTS. It was solved by replacing the cluster.
It had something to do with the Can Bus refresh rate, which was hard coded into the cluster.
I'd expect that the engineers at BRP wouldn't repeat this same error.
I'm not sure if we are talking about the same issue, but this is all the information I have to offer. I hope it helps.

 

[Snowbelt Spyder]

Well, you seem very capable and thorough trying to deal with this problem. I had a couple thoughts that may prove to be insignificant, but thought I'd share.

Dead carrier squeal - indicates either RF or audio feedback to the mic input of the transmitter. Since it occurs with the mic disconnected, you can eliminate audio feedback. So, RF feedback into the mic circuit is usually cured with the RF trap that is installed in the mic itself. With the mic disconnected, it eliminates that entry point. So to me, it makes the harness suspect between where your headset plugs in and goes back to the radio. RF is getting in the circuit someplace. That harness also should be shielded and grounded. If that's all part of the entertainment harness that came from the 2013, perhaps that installation needs revisited. I'm not familiar with that harness at all. It looks like you've been all over your output end of things and everything looks good. This is usually an input issue. And of course, the radio case itself must be grounded.

Antenna - most if not all of us here have replaced the OEM antenna - if you haven't already. Most use this one.

http://www.jmcorp.com/ProductDetail.asp?ProductID=CSCBA-300

The problem is that whoever puts the OEM antenna together uses gobs of thread locker on the stick where it screws into the base - effectively insulating the antenna. I never measured the SWR of the OEM antenna but know that the range was only a few hundred feet. The replacement will make a big improvement. Now, whether that's related to your squeal or not?????? Since you moved your antenna from the 2013 you already know how to take everything part. Remember though that you only feed the antenna with the coax center connector on both the OEM and replacement antennas. The ground connector goes to the ground strap in that left pod.

http://www.jmcorp.com/pdf/CSCBA-300---InstallInstruct12-2011.pdf

Some good general technical info on this page regarding NGP setups if your interested. Scroll down to the section on NGP antennas.

http://www.firestik.com/Tech_Docs.htm

There's also a lot of chatter on the GL 1800 forums about squeal. The pages are loading pretty slowly for me today, but you might find some info there that is not specific to the Spyder.

I suppose if you're really into it, you can setup the radio on the bench and see if it squeals. The hardest part may be figuring out how to key it. The power and antenna connections are probably fairly easy to figure out. Then process of elimination until you find what causes the squeal to return. Sounds more like a winter project, though.

Good Luck with it.

 

[IdahoMtnSpyder]

Thanks for the comments, Snowbelt. I've considered the J&M antenna but I'm not sure if it really offers much technical advantage. It's a GP, not NGP. What I haven't learned yet is what the real difference is between a coax for a GP and for an NGP antenna. Firestik says you must use a specific coax, and since J&M doesn't include a new coax I surmise their antenna must be GP.

I've pretty much ruled out audio feedback as a potential cause. At this point I'm convinced the problem is induced feedback in the microphone leads to the radio. They are unshielded all the way from the headphone jack to the radio. A quick experiment I did last night was lay a steel cookie sheet over the seat area connected to ground. It killed the squeal, but didn't help the SWR. However, when I moved the helmet I got the squeal again. All along during my tests the squeal has been dependent on where the helmet is. I can move it around and make the squeal come and go. Sometimes I can simply hold the cable close to me, or in my hand, and make the squeal stop. Other users have reported squeal with two headsets plugged in, but not with only one, and vice versa. Also, some have had the squeal go away with BRP headsets, but not J&M or Edsets, which I have.

All of the variations in causes seems to point to RF feedback, which makes me wonder if shielding the microphone wires in the harness may be the answer. I don't know enough about RF and CBs at this point to know if a feedback can get into the radio circuit by other wires or not. The feedback must be going into the mic wire though because it's being transmitted. If it was in the other audio circuits it wouldn't get transmitted, I don't think.

I'm going to see if I can get some info from CB World about whether an NGP antenna will induce feedback just like the GP does. I'm sure the NGP would be the best solution for the SWR issue as I don't know how it would be possible to get enough steel surface onto the bike to make an adequate ground plane.

The dealer service manager is going to see what info he can ferret from BRP as to how they solved the problems others have had. At this point I don't think anyone has gotten a good SWR reading, just gotten rid of the feedback.

Can anyone tell me it the BRP helmet headsets use shielded cable? I'm pretty sure my Edsets does not. I don't know about J&M.

 

[Snowbelt Spyder]

A couple of those tech papers describe what's different about a NGP coax. The big difference is that there is continuity between the center conductor and shield with there only being one connection on the antenna end, and I believe that the length is critical.

http://www.firestik.com/Tech_Docs/ngp-critical.htm

http://www.firestik.com/Catalog/K-8ngp.htm

So yes, the system is set up for a GP antenna and so is the J&M. But, sounds like your cookie sheet experiment was yielding some promising information; in that shielding is a success path. You could probably fabricate up something to shield the wiring on the bike under the body work. I wouldn't be too concerned with the SWR right now. As long as a high SWR isn't hurting the finals in the transmitter-and I don't think 3:1 is a danger, the only issue with that right now is loss of transmitting range.

 

[IdahoMtnSpyder]

I wouldn't be too concerned with the SWR right now. As long as a high SWR isn't hurting the finals in the transmitter-and I don't think 3:1 is a danger, the only issue with that right now is loss of transmitting range.

I suppose that could be true, but everything I've read, and the meter itself, indicates that any SWR above 3 is in the danger zone. Maybe the newer CBs are more rugged and can tolerate a higher SWR than in the past. But at $800 for the CB unit I'm not interested in taking a gamble that 3+ won't hurt, eventually. I already lost one CB due to poor assembly. See my thread about it getting wet inside. Range is of secondary concern in a group ride.

I ordered a Firestik NGP antenna and coax from CB World. He is optimistic that using that and getting the SWR down below 2, which it should do, will cure the squeal. We'll see! All I have to do now is modify the mounting block, or conjure an adapter, to screw the Firestik into it. And figure out how to stuff 17' of coax into the innards of the Spyder!

 

[Snowbelt Spyder]

Excellent. Please get back to us with an update when it's installed.

 

[IdahoMtnSpyder]

In my tests last night I got ferrite chokes to help. I put two on them on the headset lower cord, one above the coil and one below the coil. Someone mentioned this in one of the posts last year that worked for them. There is still some squeal if I get the helmet in the right (wrong?) place. I'll add a couple more today and see how it goes on a ride tomorrow. The ferrite chokes still don't help the SWR though, so I'll be awaiting the Firestik bits.

I've come to the conclusion that this whole CB issue is not a simple BRP lack of quality or concern. At this point I believe the cause of the problems is the basic design of the Spyder, i.e., very little steel. If the Firestik works, and a local rider said it does, then BRP, and Honda, should probably use an NGP antenna and put up with the likely complaints about having 17' of coax stuffed under the Tupperware.

And to all the naysayers who say CB is outdated technology, I have two questions. Can you talk to more than two people at a time without having to go through a pairing process, and can you talk to them if they're a mile away? I believe the answer to both questions is no. With a CB you can! Remember, newer is NOT always better! :thumbup:

 

[IdahoMtnSpyder]

No reason for squeal determined

I never have determined why I was getting a squeal when pushing PTT with the stock antenna --- except MAYBE......

On the way back from Spyderfest I lost the left channel in my headset. Apparently the left channel wire was broken or shorted in the lower cord because I could bend the cord 180° at the connector and got the audio back. I duct taped the cord into the bend for the rest of the ride home.

I wonder if by chance there was a broken wire in the lower cord all along and that broken wire somehow caused feedback that then caused the squeal during transmit. That might also be the reason I could move the cord around and make the squeal come and go. I have a new lower cord, but I'm in no mood to go through the process of reinstalling the stock antenna and coax for the CB just to find out if a broken lower cord was the cause of the squeal! Besides, the Firestik No Ground Plane antenna seems to working good.

For an update about it go here: http://www.spyderlovers.com/forums/showthread.php?92153-CB-problems-promising-development!&p=1143504&viewfull=1#post1143504

Oh, BRP had no good answers to offer when the dealer sent them an inquiry about the PTT squeal.

 

[medicineman48]

Finally, a solution

I've been reading threads till my eyes are bleary, but I don't find the answer. I read many threads about problems SL members had with their BRP CB causing a squeal when they pushed the PTT to transmit. This problem apparently reared its ugly head with the advent of the 2014 RT. Well, I've got the same problem with my 2014 RTS with a 2015 model of the BRP CB and driver headset harness that I bought from a fellow SL member. I used the entertainment harness and antenna and coax from my 2013. I never had a squeal problem with the 2013 RT.

The usual causes of such problems are, and my situation with regard to them are as follows.

A squeal can be result of a high SWR (standing wave ratio) so that's where I started checking. My system is showing an SWR over 3. It needs to be less than 2.

High SWR can be caused by a bad ground. Ohmmeter check shows I have good continuity to ground from the coax shield.

A shorted coax will cause the problem. Ohmmeter check shows I have no short in the coax.

A broken center conductor will cause a problem. There is good continuity from one end to the other of the coax so it's not broken.

A smashed or bent coax will cause a problem. I bought a new coax. It did not improve the situation.

A broken wire in the antenna will cause problems. An ohmmeter check of the antenna shows full conductivity from the bottom to the top.

An inadequate ground plane will cause a high SWR. I wheeled a 2' x 3' steel table next to the bike and connected the coax ground to it. Voila! The SWR dropped to about 1.5! Oh :cus:! The squeal still occurs. Obviously it must not be caused by a high SWR. There must be a common root cause for both the squeal and high SWR.

Induced signals in the headset harnesses can cause feedback. Disconnecting the driver headset harness from the entertainment harness did not solve the problem.

Acoustic feedback from the helmet speakers to the helmet mike will cause feedback. The squeal still occurs even when the headset is unplugged. I hear it in the handheld I'm using for testing so the squeal is being transmitted and not just limited to the bike helmet headset.

Have parts been updated that could be the answer? The radio has been updated, and the one I got is the latest version. The antenna, coax, and mounting block are the same part numbers as five years ago. The newer entertainment harness wiring configuration is the same as the old one I have.

My question is to everyone who had a squeal problem with your CB. Did you get the squeal squelched? If so, do you know what the technical fix was that solved the problem? I read several threads where the dealer changed out all the components but the squeal remained. So it must be caused by some interaction between the CB and some aspect of the bike that is not an integral part of the CB.

Has anyone successfully used a Non-Ground-Plane antenna? You have to use an NGP coax or it won't work. Not doing so may have been the reason a couple of users reported an NGP antenna didn't work for them.

I installed the CB myself and have done all the trouble shooting myself. My dealer has almost no experience with CBs and since I bought the CB in a private sale BRP won't lend a hand. The dealer did give me a copy of the installation instructions. They're almost identical to the one from five years ago. Plus, the dealers mostly just swapped out parts for most of the SL members who had this problem, and mostly that didn't help much. I'll send an inquiry to BRP and see if I can get an answer from them, but I'm hoping someone who got theirs fixed knows what the fix was.

After 7 months of having my bike in the shop, I can finally use my CB. I had to buy the Can-Am headset and adapt (mutilate) them to fit my Nolan helmets. The CB works perfectly now. I tried for over a month of communication with John from J&M audio with no solution. I could not believe that using the BRP headset would make a difference but they did.

 

[billythekidd]

When I had that problem I found that if I held the cb antenna with my hand the squeal went away. So I put a magnet on the rear headset plug cable and the problem went away. Have not had an issue since.

 

[IdahoMtnSpyder]

When I had that problem I found that if I held the cb antenna with my hand the squeal went away. So I put a magnet on the rear headset plug cable and the problem went away. Have not had an issue since.

In my case the squeal would change depending on where or how I put my hand, and where and how many ferrite chokes I put on the cable. For me the chokes were not a solution. I think I tried magnets to no avail.