[RFI] RFI to AM and ham freqs in new vehicles

[Jim Brown]

On 5/21/2023 6:11 PM, n0tt1 at juno.com wrote:
>   Personally, I think it's
> because they don't want to deal with filtering out all those RF
> square waves in the vehicles.  Or maybe they know that
> EU is, or has already, discontinued Broadcast AM radio.

This has been widely reported in the press for several months. I've been 
driving a Tesla Model 3 for 2.5 years, and have a VHF/UHF FM rig in it, 
no observable RF noise. When looking for installation advice, I came 
across several youtube videos from an OT in 5-land who first did that, 
then advanced to an HF rig. He reported that to be pretty noise free as 
well. The 12V system won't support a lot of power. I've charged at home 
from the outbuilding that houses my shack, first from a 120V/15A outlet, 
now from 240V/30A, can't hear any noise with my Kenwood TH-F6A 
(wide-band RX) probing along the power cable, or in my radios in the shack.

The Tesla designers were VERY good about RF shielding that's quite 
frequency-selective. A talkie with a duck is deaf inside the vehicle, 
but cell phone works great inside the vehicle at knee level in the 
center pedestal (and, of course, in my pocket).

As to RFI to the AM band -- I haven't probed that, but no issues on 160M 
when charging.

Vehicles are sold worldwide, so discontinuance of AM broadcasting in any 
large market could drive mfrs to drop AM in vehicles. AM has been on a 
long downward spiral for several decades, and noise has long been a 
problem. A colleague was chief engineer at WLS in the '80s and '90s 
(maybe longer, don't remember when he retired). Their 50kW clear on 890 
kHz was maybe 25-30 miles S of Chicago, and had chronic complaints of 
ignition noise from Fords that wiped them out in the northern suburbs -- 
I'm guessing 50 miles or so from their omni stick. And as we all know, 
noise has increased exponentially in the intervening decades, and the AM 
band takes the greatest hit.

Starlink, a related company, is quite the opposite. The PSU for my dish 
is mondo-noisy, took a half-dozen ferrites with multiple turns to quiet 
it down. I love that system, which I bought as redundancy for ComCast, 
whose power backup was next to non-existent. They've since improved 
quite a lot. But with no cell service in the mountains, we can't be 
without internet, so it's great to have both systems.

73, Jim K9YC

73,