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Date: Thu, 16 Feb 2006 09:36:44 -0700
From: Bill Dube <william.p.dube@noaa.gov>
Reply-To: william.p.dube@noaa.gov
Organization: NOAA Aeronomy Lab
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Radio noise saga
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The separated power leads radiate noise quite well. They are a giant 
loop antenna that is transmitting any ripple on the current to the 
battery. Alternator whine, motor whine, ingnition system input ripple 
all will radiate from such a loop.

This is a very common problem on homebuilt electric vehciles. With the 
large battery pack, folks often fine it convienient to run the power 
leads up one side of the car and back on the other. The hash from the 
motor controller and/or the charger make it impossible to use anything 
electronic inside the car if you wire it that way. Sometimes, the motor 
controller throttle input will pick up the output hash from such a loop 
and make the car undrivable.

Always run power leads as a pair. Keep the "presented area" low to 
reduce the transmitted noise.

You have found the problem.


>
> Twisted pair only reduces noise in signals transmitted THROUGH the 
> wire, and it only works if the receiver uses a differential signal. It 
> doesn't help with power wires. The curious can drop by:
>
> http://www.duxcw.com/digest/Howto/network/cable/cable4.htm
>
> It's a fairly good, brief description of what goes on. You'll usually 
> only find twisted pair in LAN cabling.
>
> Regards,
> Chad
>
> -- 
> Homepage:  http://www.flyrotary.com/
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>