Today's Message Index:
----------------------
1. 04:20 AM - Re: Help with radio intereference (Charles Reiche)
2. 05:05 AM - ANL Current Limiter to protect 10 AWG Wire (Larry Rosen)
3. 05:39 AM - Re: Help with radio intereference (Ron Brown)
4. 05:48 AM - Re: Help with radio intereference (Noel Loveys)
5. 06:08 AM - Re: Help with radio intereference (Noel Loveys)
6. 07:56 AM - Re: ANL Current Limiter to protect 10 AWG Wire (Noel Loveys)
7. 10:16 PM - Re: Help with radio intereference (jetboy)
Message 1
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| Subject: | Re: Help with radio intereference |
I would start with trying to shield the plug wires first, also you
should have shielded p lead wires goign to your switch grounding the
shield at both ends. also check that your antenna base is well grounded
thru the screws into the airframe and that belly oil or other gunk hasnt
gotten underneath the antenna mounting, seal those antennas with a good
sealant like pro-seal or fuel sealant for a long life seal, I also throw
some whitesilicone over the screw heads if the antenna is the thru hole
mounting style.
Good luck with what sounds like a non typical flying contraption!
safe flying!
Charles
----- Original Message -----
From: Andrew McMenamin
To: avionics-list@matronics.com
Sent: Sunday, May 04, 2008 2:35 AM
Subject: Avionics-List: Help with radio intereference
I hope someone can help me! I have little technical knowledge and
may have some of the technical terms incorrect but would appreciate any
advice.
I fly a Skyranger with a Simonini engine, at a controlled airfield.
The Simonini is an Italian two cylinder, two stroke liquid cooled engine
with dual Ducati ignition; two plugs per cylinder. It performs best at
over 5000 rpm. I have significant problems with noise on the radio. I
have a microair radio and a DRE 4000 headset. The radio is beautifully
clear on the ground with the engine not running. After start up, I get
an RPM - related interference which makes the radio very hard to hear
over 5000 rpm - i.e. at cruise. I am also told the Tower find it hard
to hear me. I can overcome it by reducing RPM to 4000 before
transmitting but this is not desirable!.
The interference reduces noticeably as I cut each magneto in turn at
the full power ground run up (when listening to the ATIS). This makes
me think it is ignition related.
The spark plugs are NGK resistor plugs. The plug caps are standard,
no resistor and non-shielded. The HT cables are NGK "racing" - i.e.
copper core, no apparent shielding.
The radio is positioned beside the two magneto switches on the dash,
and shielded by the aluminium firewall from the mags. It is not
shielded from the mag switch wires.
I suspect the problem is to do with the HT cables, or the plug caps,
or possibly the wires to the mag switches. I have read that I should
not use resistor caps when already using resistor plugs. Should I use
different HT leads??
Andrew
Message 2
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| Subject: | ANL Current Limiter to protect 10 AWG Wire |
I need some guidance.
I want to use 10 AWG wire from my SD-20 alternator to feed my endurance bus.
I would like to use an ANL current limiter to protect the wire.
B&C sells a 40 amp ANL and Bussman makes a 35 amp ANL (does anyone have
a source for this 35 amp ANL)
The wire table (Fig 8-3) in the connection suggests 30 amp protection
for 10 AWG wire.
Is 35 or 40 amp protection on this wire acceptable?
Would I be better off using a 14 AWG fusible link?
In addition in this circuit I want to use a S704-1 relay that is rated
at 20 amps, do I need to protect the relay? The maximum loads off the
relay are well below the 20 amps, but if it does see excessive currents,
how does it fail?
Larry Rosen
Message 3
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| Subject: | Re: Help with radio intereference |
I would try replacing the solid wire HT. I have a noise problems with my
electronic ignition system - Jeff Rose Electroair on my Velocity.
In my research into the problem, the resistance wire used with high energy
ignition systems is key to reducing ignition noise. I tried to find the
article that I had saved - but can't find it right now. Interestingly
enough, I have a Garmin 430 and a Microair 760. Guess what, the cheap radio
doesn't pick up the noise - it is the high dollar Garmin 430. Turning off
the Electroair makes the noise go away.
> Time: 11:38:36 PM PST US
> From: "Andrew McMenamin" <andrew.mcmenamin@xtra.co.nz>
> Subject: Avionics-List: Help with radio intereference
>
> I hope someone can help me! I have little technical knowledge and may
> have
> some of the technical terms incorrect but would appreciate any advice.
>
>
> I fly a Skyranger with a Simonini engine, at a controlled airfield. The
> Simonini is an Italian two cylinder, two stroke liquid cooled engine with
> dual Ducati ignition; two plugs per cylinder. It performs best at over
> 5000
> rpm. I have significant problems with noise on the radio. I have a
> microair radio and a DRE 4000 headset. The radio is beautifully clear on
> the ground with the engine not running. After start up, I get an RPM -
> related interference which makes the radio very hard to hear over 5000
> rpm -
> i.e. at cruise. I am also told the Tower find it hard to hear me. I can
> overcome it by reducing RPM to 4000 before transmitting but this is not
> desirable!.
>
>
> The interference reduces noticeably as I cut each magneto in turn at the
> full power ground run up (when listening to the ATIS). This makes me
> think
> it is ignition related.
>
>
> The spark plugs are NGK resistor plugs. The plug caps are standard, no
> resistor and non-shielded. The HT cables are NGK "racing" - i.e. copper
> core, no apparent shielding.
>
>
> The radio is positioned beside the two magneto switches on the dash, and
> shielded by the aluminium firewall from the mags. It is not shielded from
> the mag switch wires.
>
>
> I suspect the problem is to do with the HT cables, or the plug caps, or
> possibly the wires to the mag switches. I have read that I should not
> use
> resistor caps when already using resistor plugs. Should I use different
> HT
> leads??
>
>
> Andrew
>
>
Message 4
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| Subject: | Help with radio intereference |
Sounds like the same type of ignition they put on the Rotax 582. That
engine uses both resistor plugs and resistor plug caps (5k plugs BR8ES and
5K resistor caps.) Btw they recommend you only buy solid core plugs, not
the ones with the screw on terminal. The solid core plugs have a stronger
heavies top than the aluminium screw on clip. The general rule of thumb is
to use either resistor plugs or resistor caps... The Duc ignition seems to
be the exception that makes the rule.
It that doesn't work. You can then try looking at shielding your spark plugs
or installing an antenna a bit more distant from the engine... I'll go out
on a limb here and bet one full bubblegum the resistor plugs and resistor
caps will do the trick. Any takers J
Noel
From: owner-avionics-list-server@matronics.com
[mailto:owner-avionics-list-server@matronics.com] On Behalf Of Andrew
McMenamin
Sent: Sunday, May 04, 2008 4:06 AM
Subject: Avionics-List: Help with radio intereference
I hope someone can help me! I have little technical knowledge and may have
some of the technical terms incorrect but would appreciate any advice.
I fly a Skyranger with a Simonini engine, at a controlled airfield. The
Simonini is an Italian two cylinder, two stroke liquid cooled engine with
dual Ducati ignition; two plugs per cylinder. It performs best at over 5000
rpm. I have significant problems with noise on the radio. I have a
microair radio and a DRE 4000 headset. The radio is beautifully clear on
the ground with the engine not running. After start up, I get an RPM -
related interference which makes the radio very hard to hear over 5000 rpm -
i.e. at cruise. I am also told the Tower find it hard to hear me. I can
overcome it by reducing RPM to 4000 before transmitting but this is not
desirable!.
The interference reduces noticeably as I cut each magneto in turn at the
full power ground run up (when listening to the ATIS). This makes me think
it is ignition related.
The spark plugs are NGK resistor plugs. The plug caps are standard, no
resistor and non-shielded. The HT cables are NGK "racing" - i.e. copper
core, no apparent shielding.
The radio is positioned beside the two magneto switches on the dash, and
shielded by the aluminium firewall from the mags. It is not shielded from
the mag switch wires.
I suspect the problem is to do with the HT cables, or the plug caps, or
possibly the wires to the mag switches. I have read that I should not use
resistor caps when already using resistor plugs. Should I use different HT
leads??
Andrew
Message 5
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| Subject: | Help with radio intereference |
Shielding the P leads is a good idea. It should be part of the original
installation, but... only shield them at one end, where the ground should be
strongest. Typically this will be the engine end however some switches have
grounded cases at which time the shield should be grounded at the switch
end. Shields should NEVER be grounded at both ends because if there is a
difference in the strength of the ground from one end to the other (there
will be) you have just constructed a capacitive couple to make the
interference worse.
Noel
From: owner-avionics-list-server@matronics.com
[mailto:owner-avionics-list-server@matronics.com] On Behalf Of Charles
Reiche
Sent: Sunday, May 04, 2008 8:43 AM
Subject: Re: Avionics-List: Help with radio intereference
I would start with trying to shield the plug wires first, also you should
have shielded p lead wires goign to your switch grounding the shield at both
ends. also check that your antenna base is well grounded thru the screws
into the airframe and that belly oil or other gunk hasnt gotten underneath
the antenna mounting, seal those antennas with a good sealant like pro-seal
or fuel sealant for a long life seal, I also throw some whitesilicone over
the screw heads if the antenna is the thru hole mounting style.
Good luck with what sounds like a non typical flying contraption!
safe flying!
Charles
----- Original Message -----
From: Andrew <mailto:andrew.mcmenamin@xtra.co.nz> McMenamin
Sent: Sunday, May 04, 2008 2:35 AM
Subject: Avionics-List: Help with radio intereference
I hope someone can help me! I have little technical knowledge and may have
some of the technical terms incorrect but would appreciate any advice.
I fly a Skyranger with a Simonini engine, at a controlled airfield. The
Simonini is an Italian two cylinder, two stroke liquid cooled engine with
dual Ducati ignition; two plugs per cylinder. It performs best at over 5000
rpm. I have significant problems with noise on the radio. I have a
microair radio and a DRE 4000 headset. The radio is beautifully clear on
the ground with the engine not running. After start up, I get an RPM -
related interference which makes the radio very hard to hear over 5000 rpm -
i.e. at cruise. I am also told the Tower find it hard to hear me. I can
overcome it by reducing RPM to 4000 before transmitting but this is not
desirable!.
The interference reduces noticeably as I cut each magneto in turn at the
full power ground run up (when listening to the ATIS). This makes me think
it is ignition related.
The spark plugs are NGK resistor plugs. The plug caps are standard, no
resistor and non-shielded. The HT cables are NGK "racing" - i.e. copper
core, no apparent shielding.
The radio is positioned beside the two magneto switches on the dash, and
shielded by the aluminium firewall from the mags. It is not shielded from
the mag switch wires.
I suspect the problem is to do with the HT cables, or the plug caps, or
possibly the wires to the mag switches. I have read that I should not use
resistor caps when already using resistor plugs. Should I use different HT
leads??
Andrew
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Message 6
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| Subject: | ANL Current Limiter to protect 10 AWG Wire |
Larry:
There are two reasons to use the fuse. One is to protect the wire... The
other is to protect the alternator. Putting a 35 or 40A fuse of any kind on
a 20A alternator doesn't give the alternator any protection from over draw
or short circuit. To protect the wire place the fuse (no more than 20A) as
close to the alternator as is feasible. If you want 20 A protection and
think you might come across short spikes use a 20A slo-blo fuse.
The relay you have chosen is rated at 20 A. I would go with a bigger
(higher capacity) relay. If your aircraft is not certified (AB) I would
check out a relay used for RV batteries. They are usually around 30 A.
However those relays are rated to switch that current. Each time the relay
is either opened or closed under load there are little sparks that slowly
eat the contactors inside the relay. The relay is more than able to handle
20 amps continuously. If the relay is over driven it will melt.
Noel
-----Original Message-----
From: owner-avionics-list-server@matronics.com
[mailto:owner-avionics-list-server@matronics.com] On Behalf Of Larry Rosen
Sent: Sunday, May 04, 2008 9:29 AM
Subject: Avionics-List: ANL Current Limiter to protect 10 AWG Wire
I need some guidance.
I want to use 10 AWG wire from my SD-20 alternator to feed my endurance bus.
I would like to use an ANL current limiter to protect the wire.
B&C sells a 40 amp ANL and Bussman makes a 35 amp ANL (does anyone have
a source for this 35 amp ANL)
The wire table (Fig 8-3) in the connection suggests 30 amp protection
for 10 AWG wire.
Is 35 or 40 amp protection on this wire acceptable?
Would I be better off using a 14 AWG fusible link?
In addition in this circuit I want to use a S704-1 relay that is rated
at 20 amps, do I need to protect the relay? The maximum loads off the
relay are well below the 20 amps, but if it does see excessive currents,
how does it fail?
Larry Rosen
Message 7
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| Subject: | Re: Help with radio intereference |
Its going to be difficult to properly shield the wires. NGK used to sell shielded
plugs in their range I understand are not available now.
I had bad radio noise on a Jabiru installation and did some RFI testing of various
types of HT lead, shielding and R plugs.
Changing from carbon HT leads to inductive resistive wire yielded the best improvement.
The brand I used was Bosch so if not available something from NGK, Denso
or Magnecore might be similar. Aircraft shielded harness wire was little better
than plain copper. Resistor plugs helped, but using extra resistor caps
would be unwise.
If your HT leads from the coil packs are not replaceable, slip a small ferrite
clip-on supression bead at the coil ends, and another midway. These are obtainable
from electronics stores and normally used on audio and computer cabling.
I did this on my coil leads as they are copper, and it helped.
The other method is to shift the radio antenna as far away as practical from the
engine.
Ralph
--------
Ralph - CH701 / 2200a
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