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Old 26th August 2007, 21:49   #16
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1 Important Query: If i connect the ground wire from the amps etc., directly to the battery negative terminal...will that be good or bad?
It won't be bad. It will probably work. But why would you do such a thing? The car chassis is the best and safest way to ground your amplifier.
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Old 27th August 2007, 06:58   #17
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Exclamation Connecting Ground To Negative Terminal

Sam Sir,

That is 'cause i don't want FM interference from my radio when i blow the horn...that was one of the ideas put forward....maybe the chassis cannot handle the current the amplifier is putting through....just a notion...

I mean ground wiring kits do the same thing...and whereas people rubbish many claims there must be some basic truth in the process...
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Old 27th August 2007, 13:11   #18
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maybe the chassis cannot handle the current the amplifier is putting through....just a notion...

I mean ground wiring kits do the same thing...and whereas people rubbish many claims there must be some basic truth in the process...
No, the chassis can handle lots of current in the return path. And, in your case, it is not the problem of being able to handle the amps current.

When you are blowing the horn, there is RF produced by the arcing in either the horn or the relay. If the ground connection of the horn / relay is not electrically perfect, the signal appears in the electrical circuit on top of the battery voltage. That RF is also caught by the glass-mounted antenna.

This causes signal interference (between the real FM signal and the spurious RF at the discriminator, like 2 people talking at the same time) while playing FM, and is amplified by your HU. Should happen while playing CD too, except it would be far less.

A capacitor across the horn / relay would suppress the RF signal at source. Better grounding will prevent the resistance over which the RF would appear on battery line.

Another way is to put a balun choke in the battery line going to HU, which will suppress spurious RF on the battery line.
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Old 28th August 2007, 06:11   #19
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Smile FM Interference Solved

Dear All,

FM problem solved...Got the installer to out a capacitor connecting the horn relay...also put a thick wooden piece connecting the horn body to the car frame...instead of connecting metal to metal...connects via the wooden piece....problem solved....

Connecting the capacitor itself only recuced the noise...did not eliminate it!

DerAlte..sir...what is a 'balun choke'?

Last edited by 1self : 28th August 2007 at 06:24.
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Old 28th August 2007, 10:22   #20
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Dear All,

FM problem solved...Got the installer to out a capacitor connecting the horn relay...also put a thick wooden piece connecting the horn body to the car frame...instead of connecting metal to metal...connects via the wooden piece....problem solved....

Connecting the capacitor itself only recuced the noise...did not eliminate it!

DerAlte..sir...what is a 'balun choke'?
Good for you, @1self, now you can honk away to your heart's content, without messing up the music.

Since the cap reduced it and did not eliminate it altogether, it means one of 2 things:
1. The capacitor value needed a bit of experimentation (ignore it now, since the noise has been eliminated)
2. There is another source of RF or a loose contact which is being activated by the vibrations conducted through the chassis (this went away because of unmounting and remounting of the horn; it is still connecting metal to metal because of the bolt and nut making contact with the horn and chassis; would have gone away with a rubber washer also; but then, these things are detected only by a process of elimination). Please have all the other grounding connections checked for corrosion / rust.

A 'balun choke' (jargon; originally a BALanced-UNbalanced line coupler) is a small inductance created by winding a few turns of the wire around a small ferrite ring / rod. This small inductance is effective only for noise / high frequencies induced locally in a wire - acts like a series filter / suppressor. You can commonly find it at one end of the connecting cable of a desktop keyboard - a small plastic cylinder.
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Old 28th August 2007, 22:40   #21
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Exclamation Balun Choke

sir,

That was informative!! I see this on almost all computer & sensitive hardware, including GPS etc. Thanks a ton for the help! Also, the horns (both of them since this is a dual tone), are not touching the chassis, or any metal for that matter...they are bolted to a thick wooden piece which is in turn bolted to the chassis.

The balun choke idea is REALLY good...would like to try it in the future!
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