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davedq2(at)yahoo.com
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 Posted: Sat Jul 28, 2007 1:31 pm Post subject: Very bad RFI |
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Hello,
I joined this list with the hope that I could try to solve my problem in my Q2 with a Revmaster engine. At 450 hours on the engine I converted to auto plugs. I changed the heads and replaced the aviation plug connection with auto plug connections supplied with the conversion. The RFI is so bad that my transponder reply light looks like a timing light. My Tru Trak auto pilot won't stay booted up, and the noise is heard on my com. Things I've tried are...Lonestar mag filters and eliminator power filter. Checking all grounds and relocating several to a common grounding lug. Wrapping the plug connections with tin foil to try to shield the interference. Checking all of the antenna connections. Disconnecting various radios and avionics,trying to isolate a particular source. Nothing worked.
I used my handheld radio in the cockpit and didn't pick up any noise. I also called Revmaster and they is the ones who suggested trying the tin foil shielding.
The engine is carburated and uses a Bendix 3000 series dual mag. Plugs are NGK resistor plugs, gapped at .016". Hopefully someone has a suggestion, or should I consider going back to the aviation setup. Is there a different harness that would work? The unfortunate thing is that any work that is done on the magnito requires that the engine is removed enough to access the mag which is recessed into the firewall. Thank you. Dave D.
[quote][b]
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bobf(at)feldtman.com
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| Posted: Sat Jul 28, 2007 2:40 pm Post subject: Very bad RFI |
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I'll be interested to hear the replies on this. I am thinking about going to auto plugs for the same RFI reason on my LOM engine (Czechoslovakian) -- I'm planning on getting racing wire with 150 ohms per foot and shielding it with braid (you can get it from Aircraft spruce) and grounding only the mag end, and using heat shrink to hold the other end on the plug without a ground at each end (which defeats the shield).. Keep us advised as to what you do.
bobf
On 7/28/07, Dave Dugas <davedq2(at)yahoo.com (davedq2(at)yahoo.com)> wrote:[quote] Hello,
I joined this list with the hope that I could try to solve my problem in my Q2 with a Revmaster engine. At 450 hours on the engine I converted to auto plugs. I changed the heads and replaced the aviation plug connection with auto plug connections supplied with the conversion. The RFI is so bad that my transponder reply light looks like a timing light. My Tru Trak auto pilot won't stay booted up, and the noise is heard on my com. Things I've tried are...Lonestar mag filters and eliminator power filter. Checking all grounds and relocating several to a common grounding lug. Wrapping the plug connections with tin foil to try to shield the interference. Checking all of the antenna connections. Disconnecting various radios and avionics,trying to isolate a particular source. Nothing worked.
I used my handheld radio in the cockpit and didn't pick up any noise. I also called Revmaster and they is the ones who suggested trying the tin foil shielding.
The engine is carburated and uses a Bendix 3000 series dual mag. Plugs are NGK resistor plugs, gapped at .016". Hopefully someone has a suggestion, or should I consider going back to the aviation setup. Is there a different harness that would work? The unfortunate thing is that any work that is done on the magnito requires that the engine is removed enough to access the mag which is recessed into the firewall. Thank you. Dave D. [b]
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klehman(at)albedo.net
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| Posted: Sat Jul 28, 2007 4:19 pm Post subject: Very bad RFI |
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I run dual DIS (distributorless) ignition with high voltage coil joiners
on my subaru with a total of 12 high voltage ignition wires. I have no
igniton noise or interference but I do run highly recommended premium
8.5mm Taylor spiral wound racing wires. I run 40 thou spark plug gap
and I think my ignition voltage is quite a bit higher than most
magnetos. The Taylor website used to explain a fair bit about ignition
wires but as I recall mine are considerably more than 150 ohms per foot.
Ken
Robert Feldtman wrote:
| Quote: | I'll be interested to hear the replies on this. I am thinking about
going to auto plugs for the same RFI reason on my LOM engine
(Czechoslovakian) -- I'm planning on getting racing wire with 150 ohms
per foot and shielding it with braid (you can get it from Aircraft
spruce) and grounding only the mag end, and using heat shrink to hold
the other end on the plug without a ground at each end (which defeats
the shield).. Keep us advised as to what you do.
bobf
On 7/28/07, Dave Dugas <davedq2(at)yahoo.com <mailto:davedq2(at)yahoo.com>> wrote:
Hello,
I joined this list with the hope that I could try to solve my
problem in my Q2 with a Revmaster engine. At 450 hours on the
engine I converted to auto plugs. I changed the heads and
replaced the aviation plug connection with auto plug connections
supplied with the conversion. The RFI is so bad that my
transponder reply light looks like a timing light. My Tru Trak
auto pilot won't stay booted up, and the noise is heard on my
com. Things I've tried are...Lonestar mag filters and eliminator
power filter. Checking all grounds and relocating several to a
common grounding lug. Wrapping the plug connections with tin foil
to try to shield the interference. Checking all of the antenna
connections. Disconnecting various radios and avionics,trying to
isolate a particular source. Nothing worked.
I used my handheld radio in the cockpit and didn't pick up any
noise. I also called Revmaster and they is the ones who suggested
trying the tin foil shielding.
The engine is carburated and uses a Bendix 3000 series dual mag.
Plugs are NGK resistor plugs, gapped at .016". Hopefully someone
has a suggestion, or should I consider going back to the aviation
setup. Is there a different harness that would work? The
unfortunate thing is that any work that is done on the magnito
requires that the engine is removed enough to access the mag which
is recessed into the firewall. Thank you. Dave D.
|
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n81jg(at)aol.com
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| Posted: Sun Jul 29, 2007 8:23 am Post subject: Very bad RFI |
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I had a similar problem with RFI in my VariEze when I installed the LSE CD ignition system. I tried the foil covering of the plug leads since it seemed to be high voltage ignition noise in time with plug firing, but it had no effect on lessening the noise in the radio. I had a new set of plug leads made up and the problem was solved. Must have had a minute gap in the lead connections causing a spark gap and RFI. Your local auto parts dealer can make up leads of any length.
John Greaves
VariEze N81JG
Redding, CA
--
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Eric M. Jones
Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts
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| Posted: Sun Jul 29, 2007 8:50 am Post subject: Re: Very bad RFI |
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People only do this once....Mine was a car when I was 23. Who needs those resistor/plugs and wires anyway?
Or so I thought.
Change back to resistor wires and/or plugs and the problem will vanish.
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_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net |
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Jim Baker
Joined: 30 Mar 2006
Posts: 181
Location: Sayre, PA
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| Posted: Sun Jul 29, 2007 9:22 am Post subject: Very bad RFI |
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| Quote: |
People only do this once....Mine was a car when I was 23. Who needs those resistor/plugs and wires anyway?
Or so I thought.
Change back to resistor wires and/or plugs and the problem will vanish.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
|
Of course, Eric has this one right, too.........
____________________________________________
RFI or "Radio Frequency Interference":
Many people believe that spark plugs fire instantly. This is partly
true because they fire in milliseconds, although if one looks at an
oscilloscope pattern you will see much more than a single
instantaneous firing event. Many things also occur that you cannot
see even with the oscilloscope. Part of what you cannot see, but can
in many cases hear, is the noise that is picked up in the speakers of
your car stereo. This is called RFI, or Radio Frequency Interference.
Spark Plug Firing
Voltages:{PRIVATE "TYPE=PICT;ALT=Spark plug secondary wavefom example"}
When the breaker points or solid state ignition unit (switching
device) interrupts current flow in the primary ignition circuit and
induces current flow into the secondary windings of the coil, there
is an instantaneous voltage spike. (as seen in the illustration at
right in position A to B). This represents the voltage required to
overcome the spark plug and distributor rotor gaps. Once the spark
gaps have been bridged, the secondary voltage required to sustain the
spark across the gap is much less and drops (as seen in position B to
C above). The spark continues to arc across the gap at more or less
constant voltage until the arc is extinguished (at position D above).
This is due to coil energy drop in that it can not sustain the spark
any longer. During this arc duration (Spark Duration), the plug
actually fires several times. This is caused by high frequency
oscillations in the primary and secondary windings of the coil, which
continues to induce voltage spikes. They continue and slowly diminish
(positions D to E above) even after they are no longer strong enough
to sustain spark. All of this takes place in roughly one thousandth
of a second.
With our race designed ignition units, they concentrate their efforts
on sustaining spark duration as well as limiting the voltage drop
after the gaps have been bridged. Most aftermarket ignitions
concentrate on giving us 20° of spark duration (crank degrees) as
well as much higher spark energy output. A high performance coil
helps this out, but the Capacitive discharge and digital ignition
units assist in storing and delivering this power through the coil
more efficiently, faster and give the ability to achieve higher RPMs
more safely and efficiently in fuel mixture burning. The coil is only
the pawn of the ignition trigger or control unit. The coil is the
real workhorse and takes most of the abuse ... make sure you use a
good coil. (Read below about aftermarket ignition amplifiers and
controls)
The Cause of RFI:{PRIVATE "TYPE=PICT;ALT=RFI example"}
If we were to slow down the oscilloscope to perhaps 0.00000025
seconds and greatly expand the pattern (as pictured at right), we
would see that what appears to be consistent from position C to D in
the the first illustration above is actually a series of extremely
high bursts of energy. These energy bursts are discharged at the same
frequency band as radio and TV frequencies. It is these bursts that
make your car radio snap - crackle - and pop ... as well as just
about anything electronic including telephones, aircraft control
towers and heart pace makers by causing static and interference.
Sources of RFI:
Automotive ignition systems are not the only things that spew RFI
into the atmosphere. Lawn mowers, snowmobiles, ATV's, tractors, power
lines, traffic control devices, etc. all do it. One publication
refers it to "electronic air pollution". As many of us know, we live
in a sea of constant electromagnetic waves.
Any time you have a flow of electric current you will have a magnetic
field. Coils, relays, switches, solenoids, generators, servomotors
all affect communication equipment, electronic circuits and
computers. The higher the voltages, the more critical this becomes.
Anytime you have the spark jump a gap or a contact, you have a
miniature radio transmitter.
RFI Standards:
Back in the 1930's, engineers recognized that RFI could be a
nuisance. As the years, testing and technology advancements went by,
it turned into an even greater problem. Especially with the advent of
high-tech communications systems, computers and electronic engine
control devices. The Society of Automotive Engineers (SAE) decided to
set up standards for measuring as well as the control of RFI. These
are called "EMI Standards" or the more technical name for radio
static of Electromagnetic Interference (EMI).
The current standard for EMI was adopted in 1961 and is known as
J551. It limits RFI at frequencies between 20-1,000 MHz. All spark
plug manufacturers must adhere to it. The most common method used to
suppress RFI is to install a resistor in series with the spark plug's
center electrode.
Other ways that control RFI include:
* The metal fenders, grille and hood of your car. These provide a
shielding affect which absorbs much of the RFI emitted from your
ignition components. Plastic and composite body panels are basically
transparent to RFI and provide little to no shielding.
* The use of capacitors, silicone grease at connections, proper
grounding of all circuits and routing wires to reduce electromagnetic
interference are all helpful in reducing RFI.
* The use of carbon impregnated secondary wiring (plug wires) and
resistor spark plugs have the most impact when reducing and
controlling RFI. In our race cars with our high output ignitions, it
is best to use a specifically designed plug wire for our
applications. These are usually the what is called "Spiral Wound"
style plug wires. The construction of these wires starts with a
Ferro0-Magnetic impregnated inner core, helical wrapped copper alloy
conductor, a high dielectric insulator then a heavy fiberglass braid.
Wrapping this is a 8mm to 10mm silicone jacket. Also, secure
connections of the plug wire's terminal ends are mandatory along with
secure fitting boots.
Jim Baker
580.788.2779
Elmore City, OK
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davedq2(at)yahoo.com
Guest
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| Posted: Sun Jul 29, 2007 2:10 pm Post subject: Very bad RFI |
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John,
I still have a magnito system, so harness replacement with resistor wires would be a possible cure? My problem is that every time that I want to access the mags, I have to pull the engine. Do you use auto plugs? Thanks for your reply....Dave D
n81jg(at)aol.com wrote:
[quote]I had a similar problem with RFI in my VariEze when I installed the LSE CD ignition system. I tried the foil covering of the plug leads since it seemed to be high voltage ignition noise in time with plug firing, but it had no effect on lessening the noise in the radio. I had a new set of plug leads made up and the problem was solved. Must have had a minute gap in the lead connections causing a spark gap and RFI. Your local auto parts dealer can make up leads of any length.
John Greaves
VariEze N81JG
Redding, CA
--
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bobf(at)feldtman.com
Guest
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| Posted: Sun Jul 29, 2007 3:24 pm Post subject: Very bad RFI |
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You put me on a search and I ran across magnecor wires. magnecor.com is the website. Their 7 mm wire looks great! I think I will try that - I think I saw somewhere where it has 1500 ohms per foot.
bobf
On 7/28/07, Ken <klehman(at)albedo.net (klehman(at)albedo.net)> wrote:[quote] --> AeroElectric-List message posted by: Ken <klehman(at)albedo.net (klehman(at)albedo.net)>
I run dual DIS (distributorless) ignition with high voltage coil joiners
on my subaru with a total of 12 high voltage ignition wires. I have no
igniton noise or interference but I do run highly recommended premium
8.5mm Taylor spiral wound racing wires. I run 40 thou spark plug gap
and I think my ignition voltage is quite a bit higher than most
magnetos. The Taylor website used to explain a fair bit about ignition
wires but as I recall mine are considerably more than 150 ohms per foot.
Ken
Robert Feldtman wrote:
| Quote: | I'll be interested to hear the replies on this. I am thinking about
going to auto plugs for the same RFI reason on my LOM engine
(Czechoslovakian) -- I'm planning on getting racing wire with 150 ohms
per foot and shielding it with braid (you can get it from Aircraft
spruce) and grounding only the mag end, and using heat shrink to hold
the other end on the plug without a ground at each end (which defeats
the shield).. Keep us advised as to what you do.
bobf
On 7/28/07, Dave Dugas < davedq2(at)yahoo.com (davedq2(at)yahoo.com) <mailto:davedq2(at)yahoo.com (davedq2(at)yahoo.com)>> wrote:
Hello,
I joined this list with the hope that I could try to solve my
problem in my Q2 with a Revmaster engine. At 450 hours on the
engine I converted to auto plugs. I changed the heads and
replaced the aviation plug connection with auto plug connections
supplied with the conversion. The RFI is so bad that my
> transponder reply light looks like a timing light. My Tru Trak
|
| Quote: | auto pilot won't stay booted up, and the noise is heard on my
com. Things I've tried are...Lonestar mag filters and eliminator
power filter. Checking all grounds and relocating several to a
common grounding lug. Wrapping the plug connections with tin foil
to try to shield the interference. Checking all of the antenna
connections. Disconnecting various radios and avionics,trying to
isolate a particular source. Nothing worked.
I used my handheld radio in the cockpit and didn't pick up any
noise. I also called Revmaster and they is the ones who suggested
trying the tin foil shielding.
The engine is carburated and uses a Bendix 3000 series dual mag.
Plugs are NGK resistor plugs, gapped at .016". Hopefully someone
has a suggestion, or should I consider going back to the aviation
setup. Is there a different harness that would work? The
unfortunate thing is that any work that is done on the magnito
|
[b]
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n81jg(at)aol.com
Guest
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| Posted: Sun Jul 29, 2007 4:23 pm Post subject: Very bad RFI |
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Hi Dave,
Yes, I use auto plugs on the top run by the LSE CD ignition. I forgot to mention that the high tension leads from my coils to plugs are the spiral wound auto leads and work fine after I had new ones with secure connections made up. I am unfamiliar with the grounding you have with the auto plug leads. My problem was RFI in my headset and in a handheld radio that was isolate from the aircraft system. The latter test showed that I was receiving the RFI through the air. Your problem seems to be getting to your radios through your electrical system wiring, possibly your ignition switchs near your antenna wires, radio wiring or intercom wiring.
John
--
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