Received-SPF: none
 receiver=logan.com; client-ip=216.148.227.152; envelope-from=rlwhite@comcast.net
Date: Thu, 16 Feb 2006 10:44:26 -0700
From: Bob White <rlwhite@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Radio noise saga
Message-Id: <20060216104426.d7ccbbb5.rlwhite@comcast.net>
In-Reply-To: <list-987493@logan.com>
References: <list-987493@logan.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit

Hi Barry,

You won't get much value out of shielding the power leads.  If your
conduit is metal, then none at all. :)

Bob W.

On Thu, 16 Feb 2006 11:02:41 -0600
Barry Gardner <barrygardner@gmail.com> wrote:

> Bill and other knowledgable folks,
> 
> Is there any value in  running a braided shielding inside the conduit 
> that will carry the power leads? I'm building a plane like Buly's and 
> want to know if that's something I should just build into my electrical 
> raceway. Thanks.
> 
> Barry Gardner
> Wheaton, IL
> 
> Bill Dube wrote:
> 
> > 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/
> >> Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/
> >>
> >
> > -- 
> > Homepage:  http://www.flyrotary.com/
> > Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/
> >
> 
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/


-- 
http://www.bob-white.com
N93BD - Rotary Powered BD-4 (first engine start 1/7/06)
Custom Cables for your rotary installation -
http://www.roblinphoto.com/shop/