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Re: [RFI] Mobile amps and vehicle issues

To: wa3gin@erols.com, rfi@contesting.com
Subject: Re: [RFI] Mobile amps and vehicle issues
From: "FoMoCo EMC" <fomoco_emc@hotmail.com>
Date: Wed, 11 Jan 2006 16:28:37 -0500
List-post: <mailto:rfi@contesting.com>
It would be great if auto manufacturers offered that option or even had good technical service bulletins to inform you as to what modifications would be required to obtain a quieter vehicle.

The trouble is that from an emissions standpoint the vehicle is like an onion. You peel the first layer of noise by elimininating the ignition noise. Now you can hear the cooling fan and fuel pump so you peel that layer by fixing those issues. This keeps going until you finally get to a level (layer) that you can tolerate for weak signal work, but by that time you have modified the wiring harness, fuel pump, fuel pump driver module, cooling fan control module, engine control module, ignition coil, plugs, and ignition wires.

The cost of having this level of differentiation is large enough that when weighed against the benefit of the added sales from the option that it is a loss to the manufacturer. With the manufacturers in red ink anything that adds cost is carefully scrutinized.

Still the best bet for resolving these issues is through forums like rfi@contesting.com. The manufacturers can't offer the help at the level that most hams need. Call any of the manufacturers and they will tell you to take it up with the dealer and then when it appears as a blip on the monthly warranty reports there might be some resolution coming from the factory.


From: David Jordan <wa3gin@erols.com>
To: FoMoCo EMC <fomoco_emc@hotmail.com>
CC: rfi@contesting.com
Subject: Re: [RFI] Mobile amps and vehicle issues
Date: Wed, 11 Jan 2006 13:23:07 -0500



Ford should consider offering the option for better noise suppression. Most mobile rigs are costing over $1,000 bucks these days and on-board computer controllers can be equally expensive. I think Ford might be surprised just how many radio operators would be willing to spend another $50 or $100 bucks to ensure a relatively noise free and safe ride!

I've got the noise reduced so much in my Sport Trac I can hear the noise from the anti-lock brake sensors on my AM radio, haha.


FoMoCo EMC wrote:

It may be shameful but it is going to be the shape of things to come.

Susceptible circuitry is rampant in a vehicle. Almost every electric motor in a vehicle is speed controlled by a pulse width modulated signal. A little bit of RF into the circuit and the motor will exhibit undesired RPM variations. There are a dozen sensors on the engine and throughout the vehicle that put out low level signals that can be disrupted. Imagine what occurs when the vehicle can no longer tell if tire rotation is occuring (wheel speed sensors) or can't determine the postion of the camshaft, crankshaft, or throttle plate.

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