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Help with engine noise while using Autocom


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I have been reading the Autocom related threads and am slightly confused - not a hard thing to do :.

 

I have a Pro M1 Autocom that I operate from the tank bag of my 2003 RTP. Listeners often report significant engine noise when talking on a radio through the system. I use both Kenwood and Yaesu models. Although, the Yaesu seems to be worse, they have both presented problems. I also get noise when playing my ipod (hooked up to the same bike power in the tankbag).

 

The power source for the unit is a tankbag power connection wired (hot and ground) to the auxiliary battery of the RTP. I have also tested direct plug to both the RTP sockets with no improvement.

 

Reading the posts, it seems that the first step should be to run the hot lead to the fusebox or some other power source, but I am having trouble understanding why this configuration would be different than what I am currently using.

 

Any insights would be appreciated.

 

Ed Dailey

Philadelphia, PA

2003 RTP

2004 GS Adventure

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I have been reading the Autocom related threads and am slightly confused - not a hard thing to do :.

 

I have a Pro M1 Autocom that I operate from the tank bag of my 2003 RTP. Listeners often report significant engine noise when talking on a radio through the system. I use both Kenwood and Yaesu models. Although, the Yaesu seems to be worse, they have both presented problems. I also get noise when playing my ipod (hooked up to the same bike power in the tankbag).

 

The power source for the unit is a tankbag power connection wired (hot and ground) to the auxiliary battery of the RTP. I have also tested direct plug to both the RTP sockets with no improvement.

 

Reading the posts, it seems that the first step should be to run the hot lead to the fusebox or some other power source, but I am having trouble understanding why this configuration would be different than what I am currently using.

 

Any insights would be appreciated.

 

Ed Dailey

Philadelphia, PA

2003 RTP

2004 GS Adventure

 

Does the iPod still get interference when run on the battery rather than tank-bag power. If yes, then you need an input lead with isolation to protect from ground loop problems, for example Autocom part #1314.

A similar question would apply to battery vs. power hook-up for the radios. I have always used a Pro M-1 powered radio, thus never had this problem.

Before spending money, what happens if you connect the negative on the Autocom directly to the Aux battery earth.

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Your first issue should be to make sure that the connection between your iPod and the Autocom is an Autocom isolated lead. This will eliminate the Ground Loop Interference that is created when an intercom and any of the accessories plugged into it both share the same common ground, i.e. bike's electrical system. Were your iPod to be battery powered, you could just use the straight cable that came with your Autocom kit.

 

Second, are your Kenwood and Yaesu radios also bike powered? If so, they need to be battery powered unless the Kenwood is a TK3101 FRS/GMRS and uses the Autocom interface cable with powered battery plate.

 

If your radios are already battery powered, then make sure that your Autocom power source is clean. To wit, make sure it comes directly from the battery. If you don't want the lead to your tankbag to be hot all the time, run it through an inline switch. And be sure to install an inline fuse. A 2-amp fuse should cover it unless you're powering the TK3101 in which case 4 amp fuse should do it.

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John,

 

The iPod runs fine on its own battery. The noise problem is encountered when running on tankbag power.

 

The radios have problems both when running on their own battery or when getting power from the tankbag. The noise is only present when the engine is running.

 

Power for the tankbag already comes diretly from the aux battery (both sides). Would connecting the Autocom negative diretly to the battery be any different?

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John,

 

The iPod runs fine on its own battery. The noise problem is encountered when running on tankbag power.

 

The radios have problems both when running on their own battery or when getting power from the tankbag. The noise is only present when the engine is running.

 

Power for the tankbag already comes diretly from the aux battery (both sides). Would connecting the Autocom negative diretly to the battery be any different?

 

As Fernando says you need an isolated lead for the iPod. I have referred to the part #.

 

Connecting the Autocom directly to the battery shouldn't make any difference but it will avoid the tank-bag link for "process-of-elimation" purposes.

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John,

 

The iPod runs fine on its own battery. The noise problem is encountered when running on tankbag power.

 

The radios have problems both when running on their own battery or when getting power from the tankbag. The noise is only present when the engine is running.

 

Power for the tankbag already comes diretly from the aux battery (both sides). Would connecting the Autocom negative diretly to the battery be any different?

 

Is the noise a high frequency buzzing? If so, it could be RF interference being picked up from the ignition system. That will require a low-pass filter on the power lead.

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I would call the noise more of a clicking than a buzzing. Noise only occurs when the engine is running (not when the ignition is in the on position). I also think the noise modulates with engine speed.

 

The iPod problem is not a major issue. I typically run on battery power.

 

The Autocom problem, on the other hand, is not good when I am trying to communicate with multiple people while riding.

 

There are other things on the RTP grounded to the negative of the aux battery. Do I have a ground loop problem? Is there a remedy?

 

Thanks everyone for the continued help.

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Ed, I'm not sure what the problem is with the radios on battery power. I (and thousands) of others have been happlily using radios + Autocom systems on BMW R11xxRT machines for many years. You may have to experiment with shielding of some sort. If you line the whole tank-bag with 2 layers of aluminum foil, does that help? I am not suggesting this as a permanent solution, merely as part of the investigation.

You could always ring Autocom America.

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Just a shout out for those who wonder, "What's a ground loop?"

 

Ground loops happen when you have different power sources at different potentials (different voltages). You get power flowing through the ground wires (negative wires in a DC voltage system) which causes nasty noises and funky performance. Rule number one in electrical land: Check your ground! When in doubt, isolate the power systems.

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Thanks everyone for the continued advice.

 

I will work on isolating the ground and see if that works.

 

I guess another obvious check would be to see if the interference exists if I run the Autocom off a 9 volt battery.

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Hi folks,

 

If you unplug ALL accessory leads (music, phone, transceiver, GPS etc) from your Autocom system and then listen to it when bike powered with the engine running it should be clean (without interference), especially if the negative is connected directly to the bikes battery.

 

If so then any induced interference is being picked up via either the accessory leads or the accessories themselves.

 

It is useful to remember that while Autocom leads are shielded to help reject undesirable electrical interference, most accessories used are often not shielded!

 

Also remember that unplugging an accessory from a lead leaves that lead to act as a floating antenna as it has no load attached and so is likely to become more susceptible to interference pick up, so its important to unplug the lead/s from the main Autocom box if not being used.

 

Plug one lead & accessory back in at a time and test for interference until you discover which lead/accessory is the problem.

 

A buzzing sound related to engine RPM is often alternator whine, whereas a ticking sound related to engine RPM is more likely HT (plugs/coils) interference.

 

If both Autocom and accessory are bike powered you most often require an isolated interface lead to protect the device and eliminate earth loops/ interference

 

The noise described would suggest that it may be HT interference and so it may be worth testing an earth strap from the bikes battery to the tank, as some tanks are not earthed and so emitted HT can radiate from the tank. Earthing a metal tank often helps in such cases.

 

As was said; testing the Autocom with a PP3 9 volt battery will help to eliminate noise coming up the power line, and also help discover if the interference is airborne such as HT, but as the built in regulator and smoothing is very good especially if earthed directly to the bikes battery I doubt its that, more like Isolation issues on accessory leads or HT.

 

Cure for isolation issues is isolation leads,

 

Cure for HT issues is relocation of leads/accessories or earthing the tank (if not plastic) or shielding HT coils/leads with metallic covers that are well earthed to bike battery negative.

 

Sometimes a metal plate that’s earthed in the bottom of the tank bag can help with HT issues, or a noise filter on the power cable as close to the main unit as follows; one 3A diode in-line with the positive lead. Another 3A diode from ground/negative to the positive lead such that current passed from negative to positive (if you get this round the other way it will just keep blowing fuses) and a 25 volt 1000uF (or more) capacitor across the positive and negative after the diodes, again get the polarity the right way round. (All of this could go in the battery compartment and should filter out most noise, but it cannot help with isolation issues or interference on accessories or their leads)

 

Hope that helps

 

Autocom-UK-Tom

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OK, here is the latest.

 

All tests done with radio on battery (not bike) power.

 

All accessory leads unplugged - No resolution.

 

Tried the 9v battery - no noise problem.

 

Went back to bike power and isolated the ground to the aux. battery - back to noise.

 

Disconnected antenna from back of bike (RTP / std. antenna mount) - no noise. Touch antenna base to metal on back of bike, noise is back.

 

Tank is plastic - don't think that contributes.

 

Noise modulates with rpm change.

 

Ground loop?

 

Now what?

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OK, here is the latest.

 

All tests done with radio on battery (not bike) power.

 

All accessory leads unplugged - No resolution.

 

Tried the 9v battery - no noise problem.

 

Went back to bike power and isolated the ground to the aux. battery - back to noise.

 

Disconnected antenna from back of bike (RTP / std. antenna mount) - no noise. Touch antenna base to metal on back of bike, noise is back.

 

Tank is plastic - don't think that contributes.

 

Noise modulates with rpm change.

 

Ground loop?

 

Now what?

 

(Not answering for TomB, just offering MHO).

You have a Police BMW with a remote antenna for your B2B radios. You have no noise with the antenna not connected to your antenna cable, but you do with it attached. I'd say you likely have a ground problem with that antenna. Ground the antenna or the antenna plate straight to the battery. In fact, you can test this with a pair of alligator clips and a length of wire before making it permanent. Now check to see if your Autocom picks up any noise.

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When I said unplug all accessories I also meant unplug the transceiver as well as all other accessories. This was meant to test to see if the main unit intercom box was picking up any noise via the power lead and/or from HT, which it should not if ALL other devices are unplugged and the main unit is properly earthed (IE directly to bike battery negative post). Is it clean when used like this?

 

Now plugging just one accessory back in at a time, IE just the transceiver, do you get any noise (I think yes is the case) in which case we need to look at why?

 

How are you bike powering your transceivers? Directly from the bike (if so where are you picking up the power and earth?) or via the Pro-M1? If so do you know the correct voltage and current consumption of the transceiver, especially when transmitting?

 

If the transceiver/s is suitable for being powered via the ProM1 this is normally best at the Pro-M1 has built in power regulation and smoothing filters. (IE do the transceivers work on 9 volts and draw less than 1 amp on transmit) if so then they may be suitable for bike powering via the Pro-M1 and so no isolation is normally required on the transceiver to Autocom audio interface lead, however if you independently bike power your transceivers directly from the bikes 12 volt supply they most likely need a regulator and a noise filter to reduce the 12 volts down to 9 volts and also to filter out the noise on the power. You may also need to fit in-line isolation transformers to the audio connection, one for radio output to Autocom (normally the yellow wire on Autocom transceiver leads) & one for Autocom speech out to the transceiver (normally the white wire on Autocom transceiver leads. I can go into this more if you feel it is required.

 

Fernando has a good point with ref to the antenna requiring a good ground plane that’s properly earthed.

 

Another point worth considering is sometimes when you transmit you may emit undesirable noise that can also sometimes be radiated into the bike and metallic moving parts can create additional noise that sometimes gets bounced back in to the system/transceiver either via the power supply lines or maybe even airborne.

 

An out of tune or damaged antenna is often the cause for this and also a poorly grounded antenna ground plane. Removing the antenna can considerably reduce the emitted power/noise, as can grounding the actual antenna which sinks most of the signal strength.

 

Another useful tip is to reduce metallic rubbing such as wrap each tool in your tool bag, individually in cling-film, and don’t have bike lock chains to close to the transceiver.

 

You may also find that your bike is clean but the other receiving bike/s is/are noisy. You can test this by having you ignition on but engine not running and while you are transmitting they listen to their systems with their engine running at varying RPM.

 

You may find that a simple noise filter fitted to the back of yours or their transceivers power feed can help clean this up if you cant better tune/ground plane the antenna. The filter is per my previous post.

 

Hope this helps

 

Autocom-UK-Tom

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(Not answering for TomB, just offering MHO).

You have a Police BMW with a remote antenna for your B2B radios. You have no noise with the antenna not connected to your antenna cable, but you do with it attached. I'd say you likely have a ground problem with that antenna. Ground the antenna or the antenna plate straight to the battery. In fact, you can test this with a pair of alligator clips and a length of wire before making it permanent. Now check to see if your Autocom picks up any noise.

 

I have no noise when the antenna is attached to its cable (removed from the back of the bike). All other wiring (cable routing is the same).

 

Put the antenna and cable back on the bike and tried the alligator clips. No luck - still noisy when attached to both the antenna and the antenna plate.

 

I am still kind of lost and don't want to become PITA.

 

Other than the noise, is there another way to test for ground loop? Is it possible to eliminate it?

 

Maybe I am destined to work with lots of 9v. batteries available.

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