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J&M handlebar CB on RSTD question


Midrsv

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Has anyone successfully installed a J&M handlebar CB on their RSTD. I've been working with a friend and fellow member here to install one of the units on his Tour Deluxe. It was fairly easy to install but there is an incredible amount of engine noise in the system. To the point of being unusable.

 

Initially we connected the power through a relay triggered by the aux accessory wire under the seat with the ground directly to the battery. After contacting J&M they suggested not to connect directly to the batter and to tie the positive lead into the tail light circuit and the ground wire directly to the frame. We did that also and it made a slight improvement but the noise is still very annoying. The SWR has not been set and J&M says to set that also. Woud the SWR have any effect on picking up engine noise? I am not a radio expert but that seems unlikely to me.

 

I would be interested in others experiences with this system.

 

Thanks,

Dennis

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The SWR can effect the amount of noise you pick up just as the rewiring helped eliminate some. Other things that can have a big impact is the spark plugs. Changing to resistor type plugs can eliminate most if not all of the interference. You can also ad a noise filter to dampen more.

 

In the 70's, when running CB's in my cars, adding the resistor plugs usually did the trick.

 

Dave

:080402gudl_prv:

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The SWR can effect the amount of noise you pick up just as the rewiring helped eliminate some. Other things that can have a big impact is the spark plugs. Changing to resistor type plugs can eliminate most if not all of the interference. You can also ad a noise filter to dampen more.

 

In the 70's, when running CB's in my cars, adding the resistor plugs usually did the trick.

 

Dave

:080402gudl_prv:

 

Are the original plugs resistor type? If not, is there a resistor equivalent?

 

Dennis

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I've had my J & M for almost a year now - I know the feeling of aggravation with the noise. The other thing I found was the cable connector up under the tank (I think for the CB) tends to come loose sometimes. The CB antennae I got from J & M doesn't appear to be tunable. What type of antennae did you get with the unit? I also run my XM Roadie through the J & M unit. Where it is OK, I find that I have to turn my XM up pretty far to get sounds out of both ear pieces - which to me is a hassle as I don't always like the music that loud in the ears.

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I believe the antenna is from J&M. We haven't tried to tune it yet. We still got to find a meter.

 

Dennis

 

Radio Shack used to carry meters. If not try a CB shop or order one online. $25.00 should do it.

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Stupid Question?

 

When you say noice does noice comming from engine.... Or Squelch Has to be lowered to suppress radio noice..???

 

No it is definitely engine noise. It varies with the engine speed and comes through the aux input and CB.

 

DT

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Did you unit come with the noise supressor?

 

Yes, it has the filter on the 12V positive and negative line.

 

A friend told me that he had to put a capacitor in line on his XM radio on his Gold Wing to clear up some noise. Could that work here?

 

Dennis

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  • 4 weeks later...
Yes, it has the filter on the 12V positive and negative line.

 

I have never seen filters installed on the negative line. This could be adding to your problem. To reduce noise I always used the shortest and heaviest negative line that would fit. Usually a braided cable with lugs on each end to connect the chassis of the unit to a good ground.

 

A friend told me that he had to put a capacitor in line on his XM radio on his Gold Wing to clear up some noise. Could that work here?

 

The capacitor should not be put in line (eg. in series) It should be put across the source of the noise. Capacitors are used across alternator outputs to reduce noise, and back in the day when we had points in the ignition the capacitor was used to reduce the amount of arcing across the points. It also had the side effect of reducing noise in the am radio. If you use a capacitor on the power line it should go across the 12 volt source to ground. I would think a choke (coil of wire with a ferrite core) would be a better solution. Chokes are wired in series with the power. The power passes through the choke to get to the radio.

Dennis

 

The following is an over simplification, but the basic rule is that chokes pass DC current and block AC current. The noise you hear is an AC current.

 

The capacitor does just the opposite, it blocks DC current and passes AC current. So putting a capacitor in series with your power will block any power from getting to the radio. Putting it across the power lead will shunt the noise to ground and clean up the power source to give you less noise in the circuit.

 

The basic premise of putting filters on the power is that the noise is getting into your radio through the power. That is not the only way noise can get into the system. It can also be radiated into the system from the iginition circuit, plugs and coil. To tell the difference you listen to the noise at the lower RPMs. If the pitch of the noise is low enough that you can sing along with it, then its source probably the iginition system. If the pitch of the noise is to high for you to sing, then it's source probably the charging circuit.

 

Best of luck.

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I know this might sound far off,

 

But has anyone thought about shielding the unit's electrical wiring to keep out the interference from the plugs or alternator. I've not had to deal with this issue for a while, but it seems to me that when I did, I wrapped the wiring in aluminum foil and then covering everything a with coiled plastic wire loom.

 

Just a thought,

 

Rick

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