[RFI] Ignition Noise, HF Mobile, FORD

David Jordan wa3gin at erols.com
Mon Jun 16 09:45:42 EDT 2003


I'm a happy Ford truck owner as well.  They are noisey beast.  You'll 
have to bond all the sheet metal to the frame rail, not just the hood. 
 You'll also have to run a bonding strap from the negative of the batter 
to the frame rail. Ford make one good connection from the batter to the 
engine block but the chassic and the engine are both on rubber 
grommetts. Use your frame rail as your ground buss. Run bonding straps 
from the rail to all the fenders, etc. Measure the resistance across the 
door hinges. If the resistance is over 2 ohms, install a shunt across 
the hindge. Bond the tail pipe to the frame rail at three points, the 
tail pipe, between the resonator and the muffle and between the muffle 
and the cataletic converter.

Also, the brake sensors produce a lot of noise.  Make your test while 
parked or you'll just add another noise component to the mix.

Your power leads from the radio should be going directly to the battery. 
 So, as not to void my warrantee I installed a second battery inthe 
truck bed and use it as dedicated power for the transceiver.  Your coax 
from the antenna should be bonded to the frame rail as close to the base 
of the antenna as possible. Installation of an antenna isolator would 
help eliminate any common mode noise that might be pickedup by the coax.  

Good Luck,

p.s. check our our web page at www.thenighthawks.com...plenty of 
information on mobiling, etc. The NightHawks are a pure mobile net that 
runs in the evenings on 40m from 7pm till...

Cliff Bond wrote:

>I recently installed an Icom 706 in a Ford  (2002) F-150 pickup with a 4.6
>L. V-8.  It has the Coil on Plug ignition system.
>There is very heavy ignition noise (clearly "classic" ignition noise - NOT
>fuel-pump noise).  It is s-9 on 80 and 20 mtrs - less on other frequencies.
>This is my first entry into HF mobile since HW-12's in the 60's.  I have
>tried wiggling wiring, grounding the hood and other components,
>disconnecting some cables, etc. - No luck.
>I really don't understand this coil-on-plug technology, but I have been told
>there are no resistor-plugs and of course no resistor wires.
>Any suggestions as to how to proceed would be most appreciated!  I have
>tried unplugging wiring to each plug one-at-a-time with no difference noted
>in the interferrence level.  What else could I do to further diagnose the
>precise cause/source of the interferrence?
>Could I expect to get any help from Ford?
>My latest Mobile Handbook is from the 60's - out of date to say the least.
>Does the latest Mobile Handbook edition have any information on
>modern-technology ignition systems?  My 2003 ARRL Handbook (the "general"
>Handbook) has a paragraph - not at all helpful.
>All of the RFI is through the antenna - when I disconnect the antenna from
>the mount, all RFI disappears.  I can hear it on my fixed station when the
>vehicle is in the driveway.
>Any and all suggestions would be most-appreciated.  If anyone has a similar
>installation (HF) in a similar vehicle without interferrence, please let me
>Winston-Salem, NC
>RFI mailing list
>RFI at contesting.com

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