[Kenwood] Alternator whine

[Eric Lemmon]

> Bill,
> 
> The majority of alternator whine problems I have worked on were caused
> by one of only two factors.  A battery that is on its last legs can
> cause a high AC ripple to appear across its terminals, due to a higher
> than normal internal resistance.  Loose battery terminal clamps can have
> the same effect.
> 
> However, most of the problems were caused by a poor return circuit from
> the frame of the alternator to the car body and to the battery's
> negative post.  My cure is very simple:  I attach a heavy terminal lug
> to the alternator itself, and run a #4 stranded wire from that lug to a
> lug on the body sheet metal, preferably the firewall, and another #4
> wire from that lug to the negative terminal on the battery.  The paint
> where the firewall lug attaches must be sanded down to bare metal, and
> contact enhancer such as Penetrox used.
> 
> I learned this solution when I discovered that the alternator whine
> often became much more pronounced when the headlights were on.  That's
> because the headlights- along with most accessories- use the body sheet
> metal as a return path.  When you have a properly-installed antenna
> mounted on the roof sheet metal, there will be a difference in potential
> between the shield at the antenna and the negative lead at the battery.
> Your antenna cable is completing a ground-loop circuit.
> 
> You can easily test this solution with a battery jumper cable, before
> investing in the wire and lugs.  Simply clamp one end on the battery's
> negative terminal, and the other end on the metal frame of the
> alternator.  Do this while the engine is running, and check to see if
> the whine lessens when the cable is connected.
> 
> 73, Eric Lemmon WB6FLY
> 
> B Riches wrote:
> >
> > Any comments or cures for alternator whine on transmit from fm units?  Truck in question is 2003 Ford 450 diesel with twin batteries.  Alternator was replaced and noise is less but still there.  Power cables from radio go directly to the battery that is closest to alternator.  Tried Newmar 10 amp inline filter in radio power line but made no difference.
> >
> > 73,
> >
> > Bill Riches, WA2DVU
> > Cape May, NJ
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