I recently acquired a 2007 Honda Fit. It has several problems with RFI, one
of which I find particularly puzzling.
There is a broadband noise, spaced every 20 KHz. It can be heard from 40
though 2 meters (probably on 80 as well, but I haven't done much listening
there yet). It is most noticeable on 15 meters, where it approaches S9 on the
IC-746 with a HamStick antenna. (IC-746 preamps off).
The noise is perhaps 15 KHz wide, though never totally disappears in the
frequency gap. There is a weak carrier embedded in the noise band.
It does not start until the vehicle is in motion. Once motion starts the
noise appears from 0 to maybe 15 seconds later, usually sooner than later.
Once
in motion, it switches on and off, usually more on than off. It is on for a
few seconds up to maybe 15 seconds max, will drop out for maybe a half second
to 5 to 10 seconds, then back on. There is no noticeable relation to vehicle
speed or engine speed. I can put the car in neutral while moving with no
effect on the noise.
Once the car stops (engine still running) the noise may continue for several
more seconds, but then does not reappear until the car starts moving again.
I did notice one time, just after stopping, that there seemed to be a
compressor like acoustical noise coming from up front that seemed to stop when
the
RF noise stopped. I haven't had time to follow up on this, and today it is
raining which makes it hard to do tests with windows down and/or the hood up.
Any opinions from the experts on frequency?
73 - Jim K8MR
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