REFLECTOR: Ignition Noise
John Dibble
aminetech at bluefrog.com
Mon Jun 11 19:56:55 CDT 2007
I have an transient noise also. I have the Rose EI. I can eliminate the noise by
turning down my intercom, which is ok when I'm flying solo which is most of the time.
I will check my EI ground also.
John
Ron Brown wrote:
> The firewall ground goes to the engine via a #4 cable. The engine is
> grounded to the battery via a 1/2" ID copper tube - doubles as the vacuum
> line - Engine has always turned over fine so I know I have a good solid
> ground to the engine and starter.
>
> The EI power shield is grounded at the mag after it goes to the panel and
> back. I put a Radio Shack inductor capacitor on the EI power supply
> (inductor in series, capacitor to ground) but it had no effect. I will check
> and see where the EI shields are connected - and make sure there is only one
> at the EI.
>
> If that doesn't fix it, I will try running a twisted pair from a separate
> battery directly to the EI and see what that does.
>
> THANKS again!
>
> I'll buy you a six pack if that fixes it!!!
>
> ----- 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
> >>
> >>
> >> ----- Original Message -----
> >> *From:* Chuck Jensen <mailto:cjensen at dts9000.com>
> >> *To:* Velocity Aircraft Owners and Builders list
> >> <mailto:reflector at tvbf.org>
> >> *Sent:* Monday, June 11, 2007 1:11 PM
> >> *Subject:* Re: REFLECTOR: elevator cuff was Brake authority
> >>
> >> Ron,
> >>
> >> Thanks for the cuff description, I can visualize what you were
> >> describing but since I don't have any, I was just curious. I was
> >> suffering from cuff-envy until I realized it was fashionable not to
> >> have 'em.
> >>
> >> P.S. Nice looking paint and trim job on the bird. Now that its all
> >> painted up, I'm surprised you haven't found anything that you want
> >> to change!
> >>
> >> Chuck Jensen
> >>
> >> -----Original Message-----
> >> *From:* reflector-bounces at tvbf.org
> >> [mailto:reflector-bounces at tvbf.org] *On Behalf Of *Ron Brown
> >> *Sent:* Monday, June 11, 2007 10:41 AM
> >> *To:* Velocity Aircraft Owners and Builders list
> >> *Subject:* Re: REFLECTOR: elevator cuff was Brake authority
> >>
> >> Chuck,
> >>
> >> Don't have a picture - but I can describe them. It was a C shaped
> >> piece that was installed on the leading edge of the Elevator - which
> >> reduces the gap between the back of the canard and the elevator such
> >> that when the elevator is down, the gap is reduced from what it
> >> would be if the cuff wasn't there.
> >>
> >> It was installed on the inner half, span wise of the elevator.
> >>
> >> Ronnie
> >>
> >> ----- Original Message -----
> >> *From:* Chuck Jensen <mailto:cjensen at dts9000.com>
> >> *To:* Velocity Aircraft Owners and Builders list
> >> <mailto:reflector at tvbf.org>
> >> *Sent:* Monday, June 11, 2007 10:10 AM
> >> *Subject:* Re: REFLECTOR: elevator cuff was Brake authority
> >>
> >> Does anyone have a photo of the "cuffs" that are being
> >> discussed. I'm not sure I've ever seen the cuffs on the Velo.
> >> You're welcome to email directly.
> >>
> >> Chuck Jensen
> >>
> >> -----Original Message-----
> >> *From:* reflector-bounces at tvbf.org
> >> <mailto:reflector-bounces at tvbf.org>
> >> [mailto:reflector-bounces at tvbf.org] *On Behalf Of *Laurence Coen
> >> *Sent:* Friday, June 08, 2007 12:39 PM
> >> *To:* Velocity Aircraft Owners and Builders list
> >> *Subject:* Re: REFLECTOR: elevator cuff was Brake authority
> >>
> >> Al,
> >>
> >> The way I understand it, the elevator cuffs were one of three
> >> things done to address the deep stall problem. Your current
> >> main wing was redesigned and the canard was shortened. The
> >> cuffs are no longer needed. They were a modification for
> >> existing Velocities at that time. I received cuffs with my kit
> >> but never installed them. Their purpose is to increase the
> >> stall speed of the elevator which would explain your high stall
> >> speed.
> >>
> >> Larry Coen
> >> N136LC
> >>
> >> ----- Original Message -----
> >> *From:* Al Gietzen <mailto:ALVentures at cox.net>
> >> *To:* 'Velocity Aircraft Owners and Builders list'
> >> <mailto:reflector at tvbf.org>
> >> *Sent:* Thursday, June 07, 2007 11:34 AM
> >> *Subject:* Re: REFLECTOR: Brake authority
> >>
> >>
> >>
> >> I concur with Larry - 10KIAS makes a big difference.
> >>
> >> My canard stalls at 60KIAS with just me, 65KIAS with
> >>
> >> two people up front.
> >>
> >>
> >>
> >> I still have about half the width of the elevator cuff on
> >> the elevators. It gives a very gentle pitch-buck at stall,
> >> I’ve never felt a lack of elevator authority; and I never
> >> have full aft stick on landing. However; would removing the
> >> rest of the cuff reduce the stall speed?
> >>
> >>
> >>
> >> I have my ground idle set to about 500 RPMs (Lyc
> >>
> >> IO-540 with two mags) which is pretty much as slow as
> >>
> >> it will run
> >>
> >>
> >>
> >> My engine idle is about 850; that’s about 210 rpm on the
> >> prop.
> >>
> >>
> >>
> >> Al
> >>
> >> --------------------------------------------------------------
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> >
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> >
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>
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>
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>
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