REFLECTOR: Ignition Noise

Wed Jun 13 07:01:07 CDT 2007

Actually, the noise has been there for quite a while - but in the past it 
always improved after a few minutes to the point it was not a nuisance after 
a few minutes of running.  But now the noise is continuous.

The strange part is the Microair 760 #3 COM doesn't have this problem. 
Turning off the PS4000 Intercom/Audio panel has no effect.

----- Original Message ----- 
From: "steve korney" <s_korney at hotmail.com>
To: <reflector at tvbf.org>
Sent: Wednesday, June 13, 2007 12:59 AM
Subject: Re: REFLECTOR: Ignition Noise

>
> Ronnie...
>
> Two questions
>
> Have you had the noise all the time or did it just crop up... And, can you
> move the EI unit off the firewall just for a test to see if it is just to
> close to the radio itself...???  2 amps X 25000 volts = 50,000 watts.....
> That's as much as some radio stations...  I think...
>
>
> Best... Steve
>
>
>
>
> ----Original Message Follows----
> From: "Ron Brown" <romott at roadrunner.com>
> Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> CC: aeroelectric-list at matronics.com
> Subject: Re: REFLECTOR: Ignition Noise
> Date: Tue, 12 Jun 2007 20:56:00 -0400
>
>
> Sorry, Brian, No Beer tonight!!!
>
> I have worked all day chasing the noise problem on my Garmin 430:
>
> Disconnected the shield for the power to the EI at the instrument panel 
> (it
> was indeed grounded on both ends), found a loose ground wire on the single
> point grounding terminal block on the panel; ran the Jeff Rose EI off an
> independent battery, using a separate twisted wire, grounded only at the
> Electronic Ignition end; installed a big capacitor at the EI end of the
> power wire, installed the Radio Shack inductive noise filter kit  swapped
> out the direct fire coils (NAPA IC39SB); replaced one plug wire at a time,
> removed the EI timing head so that I could spin it and make sparks while 
> the
> engine was not running looking for spark jumping anywhere, none found.
>
> I'm tired - I think I'll drink the beer that I was going to send you - and
> go to bed and sleep on it!!!  (and copy the Aeroelectric list and see if
> anyone else has any suggestions short of replacing the EI with a Slick -
> ain't going there!!!!)
>
> ARRGGHHHHH!!!
>
> Ronnie Brown
> Velocity 173 Elite RG - IO360 Lycoming
>
> ----- Original Message -----
> From: "michalk" <michalk at awpi.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Monday, June 11, 2007 3:21 PM
> Subject: Re: REFLECTOR: Ignition Noise
>
>
> "power for the EI is in a shielded wire"
> "the EI is grounded on the firewall"
>
> Do you mean that your power path to the EI is battery->panel switch->EI?
>   And that this wire is a single conductor shielded wire?
>
> How does your firewall ground return to the battery?  If you patch in a
> battery to your EI and do not send this power down the duct, does that
> solve the problem?
>
> You have two problems.  First, your 430 is a receiver of this noise, and
> second, your EI is generating this noise.
>
> Fixing the noise generator usually makes other things work better, so
> start there.  The EI may have a large dV/dT, meaning a large voltage
> spike in a short time causes magnetic flux lines and electrical fields
> to be coupled into other things.
>
> If your shield is connected in two places, remove the one closest to
> your instrument panel.  If the noise goes away, good, but you still have
> a problem.  The EI sent current down that shield because its a least
> path of resistance back to your battery.  Impedance goes up as frequency
> goes up ... not just resistance.  Your EI will be much happier giving
> you a stronger spark if you fix the root cause of your problem.  Look at
> your ground path.  No need really for shielded wires.  The real need is
> to have your power and ground wires twisted.  Shielding is for
> capacitive noise.  If your power is balanced (no common mode noise) then
> there is no energy to capacitively couple.  Most likely you are
> magnetically coupling the noise.
>
> Don't fix the symptom, fix the problem.  Use twisted wire, and if you
> still want shielded, shield it at the EI(the radiator), not at the
> instrument panel.  Try to not ground your EI power to the firewall.
> Even if the ground is attached to the firewall, the electricity will
> like that path better, resulting in lower noise.
>
> I'll bet you a beer that will fix it.
>
>
> Ronnie Brown wrote:
> > The headsets are grounded at the PS4000 intercom and no where else (but 
> > I
> > will verify)  The head set wiring is through the keel, EI is powered and
> > grounded through the right side duct.  Power for the EI is in a shielded
> > wire and the shielded wire is grounded at the mag - by way of the panel.
> > Now that I think of it, the EI shield is grounded twice!  Might need to
> > lift
> > one end.  Hmmm - thanks for the suggestions, Brian!
> >
> > The EI is grounded on the SS firewall as well as to the engine (but not
> > using a braided wire - wonder if that would help?)
> >
> > Ron
> >
> > ----- Original Message -----
> > From: "michalk" <michalk at awpi.com>
> > To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> > Sent: Monday, June 11, 2007 2:12 PM
> > Subject: Re: REFLECTOR: Ignition Noise
> >
> >
> > It's not a high frequency coupling.
> >
> > I would guess that your antenna shield is a ground path for your EI.
> > Are your headset jacks insulated from the instrument panel?  Or, do your
> > headset wires share a common ground with your EI?
> >
> > Ron Brown wrote:
> >> Actually, I have been chasing a spark noise in my Garmin 430 for a
> >> several weeks.  It is only coming in the 430, it goes away when I turn
> >> off the Jeff Rose Electroair electronic ignition, it changes frequency
> >> with engine RPM, it does not come in to the #2 com which is a lowly
> >> Microair 760, it does not make noise if the antenna is disconnected 
> >> from
> >> the 430.  Arrrggghhh!
> >>
> >> I have changed antennas from right to left, used a portable antenna,
> >> bought new plugs and plug  wires, connected the 430 to a separate
> >> battery, swapped 430's with a friend, removed ground wires, cleaned and
> >> retightened them, installed noise filters on the 430 and Electroair,
> >> removed and inspected new plugs and new wires.  Next I am going to
> >> remove the timing unit from the distributor hole, spin the unit and see
> >> if I can hear sparks, then try  replace one high energy coil at a time.
> >>
> >> We are planning to fly to Colorado next week and I sure would like to
> >> NOT hear sparking noises when I am receiving a far away aircraft or 
> >> ATC.
> >>
> >> Any other suggestions from the collective???
> >> Ronnie
>
>
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