I don't like to be the bearer of bad news, but the dealership has no idea
what RFI is. They know the words and there is a problem with some Jeep
models, but that's as far as they go. Experience follows:
While somewhat of an esoteric problem with RFI: the "Water Hole"
surrounding 1420.405751 MHz. This is the emission line of celestial and
deep space hydrogen designated by HI. The Water Hole is protected spectrum
by international agreement, including the US. Well,......., read on.
We have a 2018 Jeep JL Rubicon. It, of course, includes the capability of
serving as a hotspot for the internet and making cell phone calls. As
such, it contains a cell modem as part of the electronics behind the video
display in the dash. That modem operates at nominally 700 MHz (I've easily
detected its fundamental frequency output on the spectrum analyzer) . The
second harmonic screams out of the assembly and blankets the hydrogen line
such that I can not do radio astronomy on that frequency. It ceases
"looking for mommie" - finding a cell tower as we have no cell coverage at
home - after sitting untraveled for 3 or 4 days. Does it track my
travels? Absolutely yes, but that's a different problem.
I have four times contacted the local dealership where we bought the
vehicle. They have absolutely no inkling of what I'm talking about other
than recognizing the term "Radio Frequency Interference". I've sent Jeep
in Toledo - their engineering department - three letters documenting,
screen grabs, the interference both as captured on the spectrum analyzer of
the second harmonic of the cell modem and in the time domain from my
receiver as captured on the laptop at 1420 MHz (after some downconversion
and detection). There has been absolutely no response from them, either,
other than a form email "thanking me for my interest in Jeep".........which
we already own. Thanks, but no thanks!
Frustrated......? Yes.......! There are instructions online on disabling
the cell modem, but since we camp off-grid in many...many locations which
do not have any cell coverage or amateur repeaters, I'm reluctant to do
so. In addition, it involves literally taking the whole dash apart which
I'm not into attempting.
All I can communicate is, "good luck"........and, there really is no such
thing as "luck". YMMV......😇
Dave - WØLEV
On Sat, Aug 26, 2023 at 11:49 PM Glenn Little <glennmaillist@bellsouth.net>
wrote:
> Take it back to the dealer and insist that they fix the problem.
>
> The problem is poorly designed and implemented inverters for the battery
> and electronics.
> It probably does not meet part 15 FCC rules for unintentional radiators.
>
> Glenn
>
>
> On 8/26/2023 12:59 PM, Donald S Brant Jr wrote:
> > If you are describing a problem with AM reception, it could be EMI from
> all of the inverters, etc. in the car, interfering with reception, rather
> than an antenna issue. I had heard that car makers were trying to move
> away from having AM to side step this issue. 73, Don N2VGU
> >
> >
> >
> >
> >
>
> --
> -----------------------------------------------------------------------
> Glenn Little ARRL Technical Specialist QCWA LM 28417
> Amateur Callsign: WB4UIVwb4uiv@arrl.net AMSAT LM 2178
> QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
> "It is not the class of license that the Amateur holds but the class
> of the Amateur that holds the license"
>
>
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