[Elecraft] Mobile high power

[Jim Brown]

On 5/6/2019 9:14 AM, Bert Craig wrote:
> I run approx. 200 watts from my mobile. It's been trouble free over the last four or five years. To the best of my knowledge, no adverse effects on other vehicles either. I do use LMR-240uf throughout and employ numerous snap-on ferrites as well as a full toroidal RF choke between the output of the amp and the antenna.
The right place for serious TX chokes is at the antenna feedpoint, NOT 
at the rig.
> Also, all units are grounded directly to the vehicle chassis and bonded to each other.

Proper bonding in a vehicle is different from bonding in a fixed 
station. In general, rigs should NOT be bonded to the vehicle chassis, 
and contrary to what is written on the site of a so-called mobile 
authority, DC power should be a pair run directly from the battery, 
ideally a twisted pair.  Fundamental reason is that bonding the rig to 
the chassis provides a loop return path for noise and coupling RFI 
to/from the vehicle's computers. Also, the rig is not the source of RF, 
it's the antenna!

73, Jim K9YC

> So far, so good.
>
> Vy 73 de Bert
> WA2SI
>
> -----Original Message-----
> From: Charlie T <pincon at erols.com>
> To: elecraft at mailman.qth.net
> Sent: Mon, 06 May 2019 11:24
> Subject: [Elecraft] Mobile high power
>
> Has anyone considered the liability of running very high power mobile?
> What if you're running a KW, and gave a call on 20M.  Suddenly,  the guys
> brakes in the vehicle next to you locked up causing a multiple vehicle
> crash?
> I realize this is an extremely hypothetical and unlikely case, but these
> smart vehicle computer systems can't be all THAT immune to all sorts of RFI.
>
> I know the cruise control my 2000 Dakota would mysteriously jump 5 MPH if I
> keyed up with only 25 watts on 222MHz.
> It would return to it's previous setting when I un-keyed.   VERY
> disconcerting eh?
>
> 73, Charlie k3ICH
>
>
>
> This begs the question: Why KX3s with KPA500s? That is what I use in my
> mobile station and it provides about 250W due to the FCC amplifier gain
> requirements. I am fine with it, as that is what I have and higher power may
> affect the vehicle. I have seen someone post a modification to remove an
> attenuator in the amp and recalibrate the power meter, but I would assume
> that Elecraft will not be allowed to do that, as the FCC Cert holder.
>
> 73,
>
> Mark
> W7MLG
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