2003 Pajaro - HF noise

Submitted: Tuesday, Jul 26, 2005 at 12:17
ThreadID: 25060 Views:1685 Replies:9 FollowUps:3
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Hi:
Can anyone help a Yankee? I own a 2003 Mitsubishi Montero Sport (know as Pajaro in Oz). I am trying to tame very bad HF noise. It is contant and disappears when I disconnect the antenna. I've grounded the frame, hood, etc etc. Radio is connect directly to battery. Antenna is on a ball mount on back left of truck.

I am an Amateur Radio operator and my call sign is K0MU. The US dealerships are not helpful.

Any 2003 Pajaro owners out there who can help.

Jay
Minnesota, USA
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Reply By: JayLyle - Tuesday, Jul 26, 2005 at 12:19

Tuesday, Jul 26, 2005 at 12:19
I forgot my email address:
jaylyle at mac dot com
AnswerID: 122096

Reply By: JayLyle - Tuesday, Jul 26, 2005 at 12:50

Tuesday, Jul 26, 2005 at 12:50
I was asked to provide more information:

1) The noise is received noise.
2) Radio is Yaesu FT-857D Ham Radio
3) Radio is connected directly to battery.
4) Antenna is on a ball mount in read of vehicle.
5) Noise stops when engine is stopped.
6) Noise does not start when ignition is placed to on (without starting). This probably precludes fuel pump noise.
7) Engine is 3.0 Liter gasoline engine.

Jay Lyle
Shakopee, MN USA
AnswerID: 122106

Follow Up By: Well 55 - Tuesday, Jul 26, 2005 at 13:52

Tuesday, Jul 26, 2005 at 13:52
Is the power cable running next to the antenna cable? If so you will get feed back from this.

It's possible that you need a shielded power cable, or run the power and antenna cable on either side of the engine bay.
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FollowupID: 377283

Follow Up By: JayLyle - Tuesday, Jul 26, 2005 at 14:34

Tuesday, Jul 26, 2005 at 14:34
Well 55:
Power is direct to battery. I've had very good response on the Pajaro forum; another fellow has given me great evidence that the fuel pump is the culprit. He suggests a coil and capacitor filter scheme on the wires leading to the fuel pump. It seems that the wire going from the computer to the fuel pump is 1/4 wavelength on 20 meters. This is where I have the worse interference.

I also found out that the coax is running right along what I think is the fuel pump control wires. I will also follow your suggestion to run the coax via another route (away from fuel pump). Your suggestion to shield the power wires leading to the battery is also a good practice with I will also do.

Thanks!

Jay
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FollowupID: 377295

Reply By: JayLyle - Tuesday, Jul 26, 2005 at 14:04

Tuesday, Jul 26, 2005 at 14:04
I have the model incorrect - in the US, the Montero Sport is known as the Challenger in Oz.
AnswerID: 122125

Follow Up By: Well 55 - Tuesday, Jul 26, 2005 at 14:28

Tuesday, Jul 26, 2005 at 14:28
Same problem can apply.
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FollowupID: 377294

Reply By: Kiwi Ray - Tuesday, Jul 26, 2005 at 14:30

Tuesday, Jul 26, 2005 at 14:30
Hi Jay
Un plug the alternator and run engine this will eliminate or identify another component
AnswerID: 122132

Reply By: JayLyle - Tuesday, Jul 26, 2005 at 14:36

Tuesday, Jul 26, 2005 at 14:36
Kiwi Ray:
That is a good idea (remove alternator wire). From what I understand, sometimes there are multiple sources of interferences.
AnswerID: 122134

Reply By: Member - Banjo The First (SA) - Tuesday, Jul 26, 2005 at 17:08

Tuesday, Jul 26, 2005 at 17:08
G'day Jay - I have a completely different vehicle yet my HF interfenece is chronic and caused by the high tension circuitry associated with the electronic injector system (diesel) - this is indicated by the noise disappearing when I take my foot off the accelerator, while mobile (fuel cut-off). Many vehicles here in Oz have the same problem and most are impossible to control - many of us have to pull over and switch off to use the HF !
AnswerID: 122151

Reply By: Footloose - Tuesday, Jul 26, 2005 at 17:28

Tuesday, Jul 26, 2005 at 17:28
This is an often referred to topic and refers to many of the more modern vehicles both petrol and diesel. The interference can be minimized but probably not eliminated by the usual range of measures.
Bonding of body parts and body to chassis including the exhaust pipe.
Rear mounting of the aerial
Clip on and wind through torroids on troublesome leads
Shielding of automotive components
Chokes and bypass caps
Placement of leads in relation to each other
Each measure may only lower the noise a bit but it all counts.
An old portable shortwave receiver with a fettite stick aerial makes a rough indicator of where some of the interference may be located.
Good luck
AnswerID: 122154

Reply By: Peter 2 - Tuesday, Jul 26, 2005 at 20:08

Tuesday, Jul 26, 2005 at 20:08
It will probably be the actual injection system itself, I used to install H F's for a crust and virtually gave up stopping the V6 Pajero's from interfering. As has been said lots of modern vehicles both diesel and petrol will cause uncontrollable interference. TD5 landies are also a problem.
I used to have fun with a mate in a pajero in traffic with my diesel troopy. The old troopy could beat him off at the lights regularly, especially when I picked a frequency around 11 megs and hit the tune button on the HF, the old V6 Paj would get the staggers big time as the RF mucked up the injection system.
A mate with a codan in an L series fuel injected subie had similar probs, sometimes it would cut the engine out. we'd be zooming down the road and then selcall him, his codan would tune before replying and the engine would cut out.
Peter
1996 Oka Motorhome

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AnswerID: 122182

Reply By: Dan 1 - Wednesday, Jul 27, 2005 at 23:28

Wednesday, Jul 27, 2005 at 23:28
Also check whether you have a electric fan on the radiator. They will cut in and out according to temp and can produce a lot of noise
AnswerID: 122441

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