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Re: Radio static/Defroster

-- [ From: human * EMC.Ver #2.5.02 ] --

>At least one other lister (Huw Powell) has the same problem I do:  static
between the rear defroster and the radio.<    (that would be me)

>The improved reception from the new antenna only made me realize that
whenever I turned on my rear defroster I get static in the radio.

Exactly.  It is subtle enough that you need a good clean system to really be
irritated by it.

>I only get static through the radio, not when I listen to a CD or tape.  I
don't think it's my install, because I used to get it in the old, factory
set-up. I've tried just about every sensible and non-sensical solution to
rid my car of the static -- including wiring the rear defroster direct to
the battery, bypassing all switches and wiring.  I still got the static. -
Joe Y.

Thank you Joe for saving me the rewiring trouble!

Another data point: it is signal strength dependent.  I'll be on Route 4 in
Durham NH listening to Maine Public Radio or WGBH in Boston, and turning on
the defroster will trash the reception.  If I then switch to WUNH, whose
antenna I am then right under, the static almost disappears.  It's not being
masked by volume - even if they are playing something quiet this is apparent
.  So, dear listers, if you have any knowledge of RF arcanery, what's up? 
Seems to me that putting the defroster into an electrical circuit is causing
it to interfere in the antenna's ability to pick up a clean signal.  Is this
how radio works?  can the defroster "out-antenna" the regular antenna, or
sheild it?  Is it acting as a diffraction grating/prism?  Could there be
some sort of filtering that would help, i.e. a small inductor in series with
the defroster, and/or a high quality capacitor to ground right at its

Is this quest doomed to failure? 
Huw Powell

HUMAN Speakers
7 Kelsey Road
Lee NH 03824


82ish coupe
Used parts store: 80 5k, 80 5kt, 82 coupe, 87 5k