This description reminds me of a similar problem I had once. It
turned out to be the DC-DC charger for my own cell phone.
Dave Hachadorian, K6LL
Yuma, AZ
-----Original Message-----
From: John Brosnahan -- W0UN
Sent: Thursday, October 28, 2010 12:46 PM
To: rfi@contesting.com
Subject: Re: [RFI] AM radio RFI from 2010 Ford Escape
Guys,
Thanks for the help so far and here are a few more specifics.
To those who suggested the dealership. I am sure they will not
be
able to add anything since the noise is not extremely strong and
will
not be detected when listening to AM stations once I am in town.
It
is only an issue when I am rural with weaker AM signals.
Thanks to Dave Hachadorian, K6LL, for his link to test the fuel
pump. This test has confirmed what I believed to be true in the
first place -- that it is NOT the fuel pump.
I do not see any noise associated with the ABS sensors as some
have
suggested as a possibility.
And there is no specific (varying) frequency associated with the
noise like the typical "while" of an alternator.
Again, the noise appears when I press the gas pedal and
disappears
(well, drops 10 dB, which is acceptable) when I let up on the gas
pedal. So if I am driving at any typical speed (25 mph to 65
mph,
say) there is a "frying" (broadband) noise that a ham rig with a
decent noise blanker would probably reduce significantly, but
that
makes it difficult to understand the commentator, and as soon as
I
let up on the gas pedal the noise drops to an acceptable level.
My guess is that it is really an issue with either the fuel
injection
system or the ignition system that shuts down when the engine is
coasting and needs no fuel -- possibly the fuel is cut entirely
off
or the ignition is turned off during coasting at speed. This
reduction in noise is much less when sitting still and letting up
on
the gas pedal, probably due to the need to maintain the engine
fuel
supply and ignition to keep the engine idling.
I again spent a few more hours of google searching to no avail.
Since it is hard to duplicate the coming and going of the noise
when
sitting still it will be hard to use a hand held receiver to
locate the noise.
I appreciate the comments so far and especially from hearing from
some old friends! ;-)
John W0UN
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