At 8:26 PM -0600 1/14/03, Jerry w0sat wrote:
>I've tried 3 types of antennas and mounts on my Pontic Aztek van .
>No matter what I've tried on HF I get into the 2 rear speakers. I
>followed the manufacturers installation spec's for the radio. I have
>run HF mobile in all my cars and vans without this type of problem .
>This pontiac Van has given me a problem that I can't find an
>answer for. I have been have been in electronics for over 50 years
>but I can,t seem to fix this problem. Any help would be appreciated.
Start with common-mode RF chokes on your RF transmission line, both
at the antenna end and at the transceiver end. See below for details.
Also put RF chokes on all other cables connected to your transceiver,
including power cables. Because DC power current may take various
routes returning to the negative terminal of your battery, you may
have to put an air-wound or appropriate low-mu ferrite or
powdered-iron core choke in the +12V supply wire, rather than a
common-mode choke.
Also put RF chokes on all cables entering your audio electronics.
Similar comments may apply to the +12V supply wire. All other
cables, e.g., to speakers, antenna(s), remote CD changer, whatever,
may be able to get multifilar common-mode RF chokes.
To make an HF common-mode choke wind ten multifilar or coaxial-cable
turns on an FT-240-43 toroid. Probably most of your cables will
require extra length to be spliced in. Sorry. Clip-on ferrite beads
don't do it for HF.
73 de Chuck, W1HIS
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