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Re: [TowerTalk] Station Ground

To: "K8RI on Tower Talk" <>,"Michael Tope" <>, "Jim Lux" <>,"Tower Talk List" <>
Subject: Re: [TowerTalk] Station Ground
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Sat, 15 Jan 2005 20:34:06 -0500
List-post: <>
> My manual says to run the negative lead directly to the
> particularly with todays unibody construction.

Yeah but they often can't even get ground connections on
microphones right, almost never get CW waveshaping right,
and other simple things.  Why would they understand a car?

> All it takes is a weak weld giving way or a rusty joint
causing the path to
> change

Let's think about that a bit Roger.

The starter and alternator in every highway vehicle
manufactured in the past 40 years is grounded to the engine
block or other major engine component.  The battery negative
primarily connects to the block, and always has at least one
smaller (number 8 or larger typically) lead to the chassis
for accessories.

Now let's assume that lead to the block comes loose. The
path is through that jumper to chassis and through driveline
bearings and housings to the engine. If you ground the rig
to the chassis, all you can possibly get is less than normal
voltage. That includes if the 200 spot welds that hold the
inner fender to the chassis and radiator support break and
your wheels fall off in the process.

If you ground to the battery and a ground connection to the
chassis or the block fails, battery current will flow over
the bath between the battery and the wire to the radio
negative and in the radio to the chassis.

Why would negative post radio grounding be a good idea?

How many vehicles have you seen where major welded
sheetmetal components just fall off, outside of train/auto
collisions or Yugo's of course??

Why would a bad weld or even a dozen bad welds would cause a
problem and allow a major chassis component to electrically

73 Tom


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