[Elecraft] Mobile high power

[Randy Farmer]

This information is now 20+ years out of date, so I don't know what the 
car companies do any more about HF EMI testing (if anything). Some of my 
radio buddies were employees of Ford, and they would arrange to drive 
new/developmental cars around under the antenna field at the old VOA 
relay site north of Cincinnati. Maybe nobody worries these days, but I 
do know that the manufacturers are VERY sensitive to anything that 
creates a driveability issue.

73...
Randy, W8FN

On 5/6/2019 12:23 PM, Dave New, N8SBE wrote:
> Most modern vehicles are tested for EMC in large chambers, where they
> are bombarded by high-power frequencies that extend up into the
> microwave range.  So, they are relatively immune to external RF fields.
>
> On the other hand, they are frequently not designed to withstand a
> powerful onboard transmitter, unless specifically designed for a
> particular market, say police/fire/ambulance.
>
> In the case of those vehicles, the assembly plant typically installs
> bonding/ground straps to bond all major metal panels.  Unfortunately,
> regular customers can't get those kits installed at the plant for them,
> and they aren't very effective as an aftermarket kit, because the
> customer would have to scrape the paint down to bare metal and access
> locations that might be completely closed off after assembly to install
> said straps.
>
> The other unfortunate effect of designing for police/fire/ambulance
> service, is that all those radios are now VHF/UHF and up.  No more HF
> radios.  They went out with the state-wide sheriff's networks of old
> that ran on 40 MHz or so.  So, that leaves the amateur radio HF operator
> twisting in the wind, both for onboard interference from vehicle
> electronics, and susceptibility of same.
>
> I heard that one OEM had declared that no one used HF any more, because
> they scanned the FCC database looking for amateur station assigned
> frequencies (ala commercial stations which are assigned fixed channels
> or groups of channels) and finding none, reached the conclusion that no
> one is using those bands any more.  Thus, all frequencies below 30 MHz
> are not protected, except for the AM broadcast band in the US, and MW in
> the EU.
>
> OEMs are concerned that their onboard entertainment radios
> (AM/FM/Sirius/XM) and their tire pressure monitor and remote keyless
> entry systems have no interference, but everything else can go to pot.
>
> At one time, I'm aware that at least one OEM tested using an Icom IC-706
> with those dummy-load like 1-inch coil resonated antennas, but I don't
> know if that is any longer the case.
>
> The ARRL TIS (Technical Information Service) maintains a database of
> information on mobile installations, including official documentation
> (if any) from various vehicle OEMs on suggested mobile installation
> guidelines.  Some OEMs used to come to Dayton with sample mobile
> installations, and answer questions but I've not seen them do this for
> some number of years.
>
> Hope this helps.
>
> 73,
>
> -- Dave, N8SBE
>
>
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