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Re: [EVDL] EV Digest, Vol 2, Issue 60

this could be done painlessly at the evdl wiki

> maybe you can make a brief webpage with this text and some pictures of
> how you did it
> Dan
> Mark Hanson wrote:
> >Hi,
> >Since everything works on my E-Porsche, I decided it's time to play with
> pesky EMI. I get really cranky if I can't hear NPR, news, Terry Grose, Car
> Talk, Garrison Kheilor, Wait,wait don't tell me etc., and I live out in the
> sticks (Blue Ridge Mountains) between the Appalachian Trail & Blue-Ridge
> Parkway. So EMI must be vertually non-existant (like when the EV is off).
> >
> >I ran the main controller cables down the left side metal enclosed channel
> of the 914 (74') E-Porsche and all control signals down the right side and
> through the center tunnel as the original conversion. I still had trouble
> picking up the weaker NPR talk channel with terry gross at lunch (that I
> listen to while getting E-parts around town). By turning off each DC
> converter in sequence I could identify the worst culprits (while on the weak
> station). (I have 2 dc-dc converters for reliability, one set to 14V and a
> backup to 13.8V). I found that the original DC converter VP-12124 that I
> designed for had proper inpu and output PI filters but the
> back up Lambda didn't. I put a standard pi-filter on from
> where the HV line comes in (a 2mH balun with .22uf X-cap & twin .0047uf
> Y-caps to RF frame ground reference). I also put a high current 1Mh 12A
> balun choke on the output for common mode RF. This got rid of the EMI from
> the DC converter.
> >
> >There was still EMI present, I could tell while the radio was on and the
> ignition key was switched on & off. It was my dash display uP controlled
> battery charger and run monitor (displays volts, RPM's Temp etc.) This thing
> has a scanning display and an internal oscillating dc-dc converter *and* is
> mounted in the dash next to the radio, oops. Since it's main function is for
> charge control, rather than choke-treat the umpteen wires coming out of it
> for conducted EMI and a shielded box for radiated, I decided to just put a
> "NPR switch" on it to turn it off while I'm listening to the FM. Now I can't
> tell when the car is on or not, I get the *same* good reception (and no
> interference from the traction control with a 200uH choke in series and
> channeled cables). That's right, no difference whether the ignition key is
> on or off, same reception on faint stations. (Don't listen to AM though but
> it appears ok).
> >Have a renewable energy day,
> >Mark in Roanoke, VA

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