On 4/10/2012 6:40 PM, Dale Svetanoff wrote:
> List mates:
>
> The link below leads you to an article from Electronic Design magazine. It
> concerns RFI issues in electric drive vehicles (and, by extension, hybrids,
> as well). The primary focus is on the interference caused to the
> entertainment system ("broadcast") radios within the vehicles. My personal
> view is that the situation is almost surely applicable to communications
> radios, as well, especially those used for HF communications.
>
> Here is the link:
We have a Prius Hybrid: No RFI issues to either the entertainment center
or the rig.
Most of the Hybrids I've seen/driven had too small a battery and light
gauge wiring to run much of a radio. The battery is so small the
manufacturer recommends you do not wire directly to the battery, but
either through the switch, or a relay that is energized only when the
ignition is on. Two other hams have newer models and they do not have
any RFI issues either. I'd suggest a heavy duty battery placed in back
along with a much larger alternator to keep it charged.
The first sentence is a blanket statement that is not true: "To enable
radio reception in electric vehicles, manufacturers must install filters
and insulate cables, since electrical signals will otherwise interfere
with music and speech transmissions" as I can point to 3 examples from
different years that have no problems in either the car entertainment
system, or the ham rigs. I can understand filters when necessary and
shielding, but "Insulation"?
Therefor this appears as an article that was not well thought out or
researched.
>
> http://www.wirelessdesignmag.com/ShowPR.aspx?PUBCODE=055&ACCT=0000100&ISSUE=1204&RELTYPE=IN&PRODCODE=00000&PRODLETT=AI.html?et_cid=2583485&et_rid=60851216&linkid=http%3a%2f%2fwww.wirelessdesignmag.com%2fShowPR%7ePUBCODE%7e055%7eACCT%7e0000100%7eISSUE%7e1204%7eRELTYPE%7eIN%7ePRODCODE%7e00000%7ePRODLETT%7eAI&CommonCount=0
>
> (Note: Due to length of the link, I hope it all comes thru the reflector
> intact. I am in hopes that you will be able to click anywhere on the link
> and succeed in getting to the article.)
It works fine in Thunderbird.
>
> To be honest, I was disappointed in the article's lack of substantial
> technical detail. (Although Electronic Design is not a publication devoted
> specifically to EMC/EMI issues, it is targeted to the electronic engineering
> community. Therefore, I was a bit surprised that this article is pretty much
> at the lay person level. Nevertheless, I felt that some of the comments
> might be of interest to readers on this reflector.)
The first sentence being a blanket statement that is not true hurt the
credibility of the article and author.
>
> One aspect of the automotive RFI issue did catch my interest: A primary
> dictum in RFI control is that you do all that you can to contain an RFI
> source (in this case, the power converter) so as to minimize propagation of
> interference via direct radiation or via the associated wires and cables.
> ("Containment" also means that I/O lines should be well-filtered.) Note that
> nowhere in the article is containment of the source mentioned. Instead, a
> lot of effort has been placed on routing of wires and insulation of the high
> power drive motor from the chassis of the vehicle. (These motors are
> typically electronically commutated DC types, no brushes.) One must guess
> that size, weight, and cost probably factor into the decisions to work
> placement and isolation issues, rather than containment.
>
> I, for one, would be delighted if someone in the automotive industry would
> reply to this posting with some supporting information as to what is being
> done in today's electric and hybrid drive vehicles for RFI control,
> especially as regards communications (be it for broadcast or two-way
> applications). I would also welcome comments from anyone associated with the
> Fraunhofer Institute and the work described in the article.
>
> Finally, I am wondering if any list members have installed either a ham rig
> (HF and/or VHF/UHF) or a scanner in an electric drive nor hybrid vehicle, and
> if so, were there any significant RFI issues to contend with? Please post so
> that we can all share in your experiences. Thanks.
As I said above, I know of three hams who drive a Prius (all different
years). Ours is one of the oldest ones, while a friend drives on about a
year old. No RFI issues at all.
73
Roger (K8RI)
>
> 73, Dale
> WA9ENA
> Sr. EMC Engineer
>
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