Today's Message Index:
----------------------
1. 05:41 AM - Subject: Re: RF interference (Jill Gernetzke)
2. 08:45 AM - Re: Re: Chinese L-7 (aka Yak 54 knock-off) (Mark Schrick)
3. 10:27 AM - Re: Re: Chinese L-7 (aka Yak 54 knock-off) (George Coy)
4. 12:36 PM - Re: RF interference (Yak Pilot)
5. 12:49 PM - Re: RF interference (Yak Pilot)
6. 02:35 PM - Re: RF interference (Scott Poehlmann)
7. 02:42 PM - Re: RF interference (Scott Poehlmann)
8. 04:23 PM - Re: RF interference (Yak Pilot)
9. 04:34 PM - Re: RF interference (Yak Pilot)
10. 07:45 PM - Re: RF interference (Scott Poehlmann)
Message 1
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| Subject: | Re: RF interference |
Scott & Group,
We manufacture coverplates for the tach generator pad. Contact me off-list.
Jill Gernetzke
M-14P, Inc.
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| Subject: | Re: Chinese L-7 (aka Yak 54 knock-off) |
I like the way they are using a STOCK Yak 54 fuselage and design a new wing
around it.
Less time and money on R&D......Chinese do not have that many people they can
throw into a new design......maybe a BILLION but who is counting.
Merry Christmas everyone.
SHREK
________________________________
From: keithmckinley <keith.mckinley@townisp.com>
Sent: Thu, December 16, 2010 1:50:10 PM
Subject: Yak-List: Re: Chinese L-7
Dear Santa.................
--------
Keith McKinley
700HS
KFIT
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323606#323606
Message 3
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| Subject: | Re: Chinese L-7 (aka Yak 54 knock-off) |
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of Mark Schrick
Sent: Saturday, December 18, 2010 11:43 AM
Subject: Re: Yak-List: Re: Chinese L-7 (aka Yak 54 knock-off)
I like the way they are using a STOCK Yak 54 fuselage and design a new wing
around it.
Less time and money on R&D......Chinese do not have that many people they
can throw into a new design......maybe a BILLION but who is counting.
Merry Christmas everyone.
SHREK
_____
From: keithmckinley <keith.mckinley@townisp.com>
Sent: Thu, December 16, 2010 1:50:10 PM
Subject: Yak-List: Re: Chinese L-7
Message 4
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| Subject: | Re: RF interference |
Hmmm!
I need to add one step to my troubleshooting procedures Scott:
Step Three: Have you added a digital tach that takes it's input off the P Leads.
If so, that is very high potential for noise addition to your aircraft.
I actually thought of mentioning that, but since you did not bring it up in your
initial email, I guessed (incorrectly) that you had not modified anything since
you put in the new spark plugs and wire kit.
To answer your question: When pulling the Tach Drive, most of the folks I know
have had a plate made that bolts on with the four corner bolts to the plate and
there you go. You make it yourself. You need to be very very careful here,
because if you remove the wrong "plate" you also will expose the gearing for
the tach drive that also is part of the air distributor drive. What I am saying
here is that if you pull the wrong plates and stuff in an attempt to put a
new cover plate over the tach drive, you can easily disturb the gearing inside,
which will in turn through your air start distributor out of adjustment and
then you are DEEP KIMSHEE! Re-timing the airstart distributor is NOT EASY regardless
of what anyone might tell you otherwise. So Scott, be very very careful
of what you take apart in that area. Without photo's it is hard for me to
describe what to take off and what not to take off. Talk to Dennis about tha
--- On Fri, 12/17/10, Scott Poehlmann <scott-p@texas.net> wrote:
> From: Scott Poehlmann <scott-p@texas.net>
> Subject: Re: Yak-List: RF interference
> To: yak-list@matronics.com
> Date: Friday, December 17, 2010, 9:03 PM
> Scott Poehlmann <scott-p@texas.net>
>
> Thanks Mark,
>
> I knew that you would have a great, step by step method.
>
> Went out to the hangar today: looks like the P-leads are
> the
> culprit--BOTH have the shielding detached from the
> connector and about 1
> cm of unshielded lead "hanging in the breeze". I'll spend
> some time
> tomorrow AM soldering the shielding to the connector (it
> appears that
> this has been done before and that the solder joints have
> failed...),
> and will advise if this doesn't fix the problem.
>
> Now for the next question: any ideas where to find a cover
> for the tach
> generator drive? I am running a Horizon digital tach (which
> takes its
> data from the mag--in fact it is wired into the back of the
> mag
> switch...), and I have no tach generator, just a big open
> fitting with a
> drive (and seal) at the bottom... Threaded on the outside,
> of course.
>
> Thanks again, and to everyone else who provided
> information. This list
> is a tremendous asset to the continued operation of these
> airplanes.
>
> Scott
>
> On 12-17-2010 10:15, Yak Pilot wrote:
> Pilot<yakplt@yahoo.com>
> >
> > Do the following:
> >
> > Remove the plug from the Tach Gen and tie it back. Run
> the aircraft. Does the noise go away? Then it is
> indeed your Tach Gen and it is most likely shielding at the
> Tach Generator plug itself. Be careful taking this
> plug apart as it is common for the soldering on these wires
> to break.
> >
> > If the noise does not go away, fly the airplane.
> Over the airport come to complete idle and then shut the
> mags off. Both mags, turn them off.
> >
> > You're now a glider.
> >
> > Did the noise go away? If it did, then you have
> a MAG noise problem. The mag noise filters will help,
> but before you go to that effort, look at the P leak plugs
> that go into the side of the mags. It is very common
> for people to twist these plugs off during some kind of
> maint. action and in the process twist the shield right off
> the plug as well. If the P Lead is unshielded you will
> have one huge amount of noise.
> >
> > If the noise is still there even when you have
> performed these steps (whcih is highly unlikely) then you've
> got some other device radiating energy in the
> aircraft. Start turning everything that you can off to
> try and identify it.
> >
> > Suggestions have been made to see if it is coming in
> via the antenna or the power wiring. I have posted
> these suggestions before, but it is something you do at the
> end of troubleshooting and not the beginning. It is
> much easier to identify the noise source and eliminate it
> where it is coming from. If you can't identify the
> noise and you are lucky enough to have it coming in via the
> power wires (again this is rare), a choke on the input power
> wiring can help eliminate the noise. This can be as
> simple as a snap on torroid, or an expensive (purchased)
> filter, that is usually some sort of "Pi L brute force"
> filter consisting of two caps and an inductor.
> Usually, snap on torroids are just as effective and much
> cheaper. Again though, noise coming in via the power
> wiring is rare. It usually is coming in via the
> antenna, and that means you MUST eliminate the noise at it's
> source.
> >
> > The tests described above will usually nail the
> problem in short order.
> >
> > Mark Bitterlich
> >
> > p.s. The reason I recommend shutting the mags
> off at idle in flight versus doing it on the ground is
> because the engine keeps wind-milling even with the mags
> off, and you can leave them off much longer while you are
> listening for radio noise and seeing if it goes away.
> Shutting the engine off with the mags and the engine
> windmilling with it at idle will not hurt anything, although
> the engine will cool off really fast, so when you turn the
> mags back on and the engine once again is actually
> "running", don't just cob the power to 100%. Bring it
> in slowly. Common sense applies.
> >
> > --- On Thu, 12/16/10, Roger Kemp M.D.<viperdoc@mindspring.com>
> wrote:
> >
> >> From: Roger Kemp M.D.<viperdoc@mindspring.com>
> >> Subject: RE: Yak-List: RF interference
> >> To: yak-list@matronics.com
> >> Date: Thursday, December 16, 2010, 1:35 PM
> >> "Roger Kemp M.D."<viperdoc@mindspring.com>
> >>
> >> Check the shielding on your Tac Generator. That is
> the most
> >> likely source
> >> for RPM related noise.
> >> Doc
> >>
> >> -----Original Message-----
> >> From: owner-yak-list-server@matronics.com
> >> [mailto:owner-yak-list-server@matronics.com]
> >> On Behalf Of Scott Poehlmann
> >> Sent: Thursday, December 16, 2010 5:07 AM
> >> To: yak-list@matronics.com
> >> Subject: Yak-List: RF interference
> >>
> Poehlmann<scott-p@texas.net>
> >>
> >> Hi All,
> >>
> >> I am aware this has been discussed before, but as
> the
> >> problem now
> >> effects my own airplane, I have am a bit more
> attentive...
> >>
> >> I have a Yak 55M with an auto-plug conversion.
> The
> >> conversion has been
> >> in place for about 3 years now (roughly 400
> hours). I am
> >> now getting RF
> >> interference picked up in the Briz radio from the
> mags/plug
> >> wires. At
> >> least I assume that is the source, as it is RPM
> dependent.
> >> It has been
> >> present since installation, but has been gradually
> getting
> >> worse over
> >> the past year or so. I assume that there is a
> shielding
> >> issue either at
> >> the mag connection or along the wires somewhere.
> My
> >> question to you is
> >> where should I start to look at trouble shooting
> this
> >> issue, and how do
> >> I go about fixing it (shy of completely replacing
> the plug
> >> wires, which
> >> I'd prefer not to do... But will do if need
> be...)?
> >>
> >> Any thoughts you might have on the matter would
> be
> >> appreciated.
> >>
> >> Thanks,
> >>
> >> Scott Poehlmann
> >> Yak 55M N155YK
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> Lists This Month --
> >> Some AWESOME FREE Gifts!)
> >> Raiser. Click on
> >> out more about
> >> Gifts provided
> >> www.aeroelectric.com
> >> www.buildersbooks.com
> >> www.homebuilthelp.com
> >>
> -Matt
> >> Dralle, List Admin.
> >> Forum -
> >> FAQ,
> >> - MATRONICS WEB FORUMS -
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> >
> >
>
>
> Lists This Month --
> Some AWESOME FREE Gifts!)
> Raiser. Click on
> out more about
> Gifts provided
> www.aeroelectric.com
> www.buildersbooks.com
> www.homebuilthelp.com
> -Matt
> Dralle, List Admin.
> Forum -
> FAQ,
> - MATRONICS WEB FORUMS -
>
>
>
>
Message 5
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| Subject: | Re: RF interference |
Hmmm!
I need to add one step to my troubleshooting procedures Scott:
Step Three: Have you added a digital tach that takes it's input off the P Leads.
If so, that is very high potential for noise addition to your aircraft.
I actually thought of mentioning that, but since you did not bring it up in your
initial email, I guessed (incorrectly) that you had not modified anything since
you put in the new spark plugs and wire kit.
To answer your question: When pulling the Tach Drive, most of the folks I know
have had a plate made that bolts on with the four corner bolts to the plate and
there you go. You make it yourself. You need to be very very careful here,
because if you remove the wrong "plate" you also will expose the gearing for
the tach drive that also is part of the air distributor drive. What I am saying
here is that if you pull the wrong plates and stuff in an attempt to put a
new cover plate over the tach drive, you can easily disturb the gearing inside,
which will in turn through your air start distributor out of adjustment and
then you are DEEP KIMSHEE! Re-timing the airstart distributor is NOT EASY regardless
of what anyone might tell you otherwise. So Scott, be very very careful
of what you take apart in that area. Without photo's it is hard for me to
describe what to take off and what not to take off. Talk to Dennis about that
for details.
Somehow I just managed to send this message when my fingers slipped on the keyboard
oops so here is the end of the message, sorry.
Going back to your noise on your radios. I hate to tell you this Scott, but those
new digital tachs that attach to your P leads are a real source of radio noise.
This is the forth time I have had a person who installed that tach start
talking about radio noise. I also have personal experience with that thing
myself.
Given that your Tach Generator is now removed from the aircraft, and you have installed
the Digital Tach that used your P leads for a input, I am 99.999% sure
that your new radio noise is from the P leads. Yes, you should repair the shields
down at the MAGs and that will help. But you also are going to have to
go back to the wires that have been attached behind the mag switch and make darn
sure that shielded wires were used there as well. Just leaving a tiny bit
of exposed wire (I.E. Where there is no shielding on the P leads) will allow
that to act as an antenna and RADIATE NOISE all over the aircraft.
In one aircraft I worked on (a Sukhoi 26) I had to replace all of that wiring to
the digital tach, and then... get ready for this.. I had to make an actual BOX
out of aluminum and enclose the whole tach inside that box (a Faraday Shield
per se) and ground all that.
So that is the downside of using that kind of Tach, I am sorry to have to say.
Its a GREAT TACH, and I love the way it works, but since it uses the P leads,
you have to really pay attention to your shielding. There is usually no filter
that can eliminate this kind of noise. Spark noise is very broad spectrum
and if you are anywhere in the near field from this noise, youre pretty much screwed.
One trick that SOMETIMES helps: Take a handheld VHF radio, remove the antenna
and stick a paperclip into the center conductor of the antenna jack. Hook headphones
to the handheld radio. Now start the aircraft and use the radio as a
test wand and run it around the wiring to try and find the source. This is not
easy and takes some effort.
Bottom line: Your noise is coming from your P leads and new tach. Good luck.
Merry Christmas.
Mark Bitterlich
--- On Fri, 12/17/10, Scott Poehlmann <scott-p@texas.net> wrote:
> From: Scott Poehlmann <scott-p@texas.net>
> Subject: Re: Yak-List: RF interference
> To: yak-list@matronics.com
> Date: Friday, December 17, 2010, 9:03 PM
> Scott Poehlmann <scott-p@texas.net>
>
> Thanks Mark,
>
> I knew that you would have a great, step by step method.
>
> Went out to the hangar today: looks like the P-leads are
> the
> culprit--BOTH have the shielding detached from the
> connector and about 1
> cm of unshielded lead "hanging in the breeze". I'll spend
> some time
> tomorrow AM soldering the shielding to the connector (it
> appears that
> this has been done before and that the solder joints have
> failed...),
> and will advise if this doesn't fix the problem.
>
> Now for the next question: any ideas where to find a cover
> for the tach
> generator drive? I am running a Horizon digital tach (which
> takes its
> data from the mag--in fact it is wired into the back of the
> mag
> switch...), and I have no tach generator, just a big open
> fitting with a
> drive (and seal) at the bottom... Threaded on the outside,
> of course.
>
> Thanks again, and to everyone else who provided
> information. This list
> is a tremendous asset to the continued operation of these
> airplanes.
>
> Scott
>
> On 12-17-2010 10:15, Yak Pilot wrote:
> Pilot<yakplt@yahoo.com>
> >
> > Do the following:
> >
> > Remove the plug from the Tach Gen and tie it back. Run
> the aircraft. Does the noise go away? Then it is
> indeed your Tach Gen and it is most likely shielding at the
> Tach Generator plug itself. Be careful taking this
> plug apart as it is common for the soldering on these wires
> to break.
> >
> > If the noise does not go away, fly the airplane.
> Over the airport come to complete idle and then shut the
> mags off. Both mags, turn them off.
> >
> > You're now a glider.
> >
> > Did the noise go away? If it did, then you have
> a MAG noise problem. The mag noise filters will help,
> but before you go to that effort, look at the P leak plugs
> that go into the side of the mags. It is very common
> for people to twist these plugs off during some kind of
> maint. action and in the process twist the shield right off
> the plug as well. If the P Lead is unshielded you will
> have one huge amount of noise.
> >
> > If the noise is still there even when you have
> performed these steps (whcih is highly unlikely) then you've
> got some other device radiating energy in the
> aircraft. Start turning everything that you can off to
> try and identify it.
> >
> > Suggestions have been made to see if it is coming in
> via the antenna or the power wiring. I have posted
> these suggestions before, but it is something you do at the
> end of troubleshooting and not the beginning. It is
> much easier to identify the noise source and eliminate it
> where it is coming from. If you can't identify the
> noise and you are lucky enough to have it coming in via the
> power wires (again this is rare), a choke on the input power
> wiring can help eliminate the noise. This can be as
> simple as a snap on torroid, or an expensive (purchased)
> filter, that is usually some sort of "Pi L brute force"
> filter consisting of two caps and an inductor.
> Usually, snap on torroids are just as effective and much
> cheaper. Again though, noise coming in via the power
> wiring is rare. It usually is coming in via the
> antenna, and that means you MUST eliminate the noise at it's
> source.
> >
> > The tests described above will usually nail the
> problem in short order.
> >
> > Mark Bitterlich
> >
> > p.s. The reason I recommend shutting the mags
> off at idle in flight versus doing it on the ground is
> because the engine keeps wind-milling even with the mags
> off, and you can leave them off much longer while you are
> listening for radio noise and seeing if it goes away.
> Shutting the engine off with the mags and the engine
> windmilling with it at idle will not hurt anything, although
> the engine will cool off really fast, so when you turn the
> mags back on and the engine once again is actually
> "running", don't just cob the power to 100%. Bring it
> in slowly. Common sense applies.
> >
> > --- On Thu, 12/16/10, Roger Kemp M.D.<viperdoc@mindspring.com>
> wrote:
> >
> >> From: Roger Kemp M.D.<viperdoc@mindspring.com>
> >> Subject: RE: Yak-List: RF interference
> >> To: yak-list@matronics.com
> >> Date: Thursday, December 16, 2010, 1:35 PM
> >> "Roger Kemp M.D."<viperdoc@mindspring.com>
> >>
> >> Check the shielding on your Tac Generator. That is
> the most
> >> likely source
> >> for RPM related noise.
> >> Doc
> >>
> >> -----Original Message-----
> >> From: owner-yak-list-server@matronics.com
> >> [mailto:owner-yak-list-server@matronics.com]
> >> On Behalf Of Scott Poehlmann
> >> Sent: Thursday, December 16, 2010 5:07 AM
> >> To: yak-list@matronics.com
> >> Subject: Yak-List: RF interference
> >>
> Poehlmann<scott-p@texas.net>
> >>
> >> Hi All,
> >>
> >> I am aware this has been discussed before, but as
> the
> >> problem now
> >> effects my own airplane, I have am a bit more
> attentive...
> >>
> >> I have a Yak 55M with an auto-plug conversion.
> The
> >> conversion has been
> >> in place for about 3 years now (roughly 400
> hours). I am
> >> now getting RF
> >> interference picked up in the Briz radio from the
> mags/plug
> >> wires. At
> >> least I assume that is the source, as it is RPM
> dependent.
> >> It has been
> >> present since installation, but has been gradually
> getting
> >> worse over
> >> the past year or so. I assume that there is a
> shielding
> >> issue either at
> >> the mag connection or along the wires somewhere.
> My
> >> question to you is
> >> where should I start to look at trouble shooting
> this
> >> issue, and how do
> >> I go about fixing it (shy of completely replacing
> the plug
> >> wires, which
> >> I'd prefer not to do... But will do if need
> be...)?
> >>
> >> Any thoughts you might have on the matter would
> be
> >> appreciated.
> >>
> >> Thanks,
> >>
> >> Scott Poehlmann
> >> Yak 55M N155YK
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> Lists This Month --
> >> Some AWESOME FREE Gifts!)
> >> Raiser. Click on
> >> out more about
> >> Gifts provided
> >> www.aeroelectric.com
> >> www.buildersbooks.com
> >> www.homebuilthelp.com
> >>
> -Matt
> >> Dralle, List Admin.
> >> Forum -
> >> FAQ,
> >> - MATRONICS WEB FORUMS -
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> >
> >
>
>
> Lists This Month --
> Some AWESOME FREE Gifts!)
> Raiser. Click on
> out more about
> Gifts provided
> www.aeroelectric.com
> www.buildersbooks.com
> www.homebuilthelp.com
> -Matt
> Dralle, List Admin.
> Forum -
> FAQ,
> - MATRONICS WEB FORUMS -
>
>
>
>
Message 6
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| Subject: | Re: RF interference |
Thanks Mark,
I didn't mention the tach because, frankly, I didn't think about it. The
tach appears to be wired at the mag switch, and and that cabling is
unshielded. I don't know if that is at issue or not, but given what
happened today, I think not...
Having said that, I am 98% certain I have found the problem. I soldered
the shield back on the right (#1) mag and now I have the problem only
when the left (#2) mag is operating (i.e., position "2" and "1+2"). I
will repeat the process with the left mag tomorrow, and I suspect that I
am done. I am not particularly happy with the quality of the solder
joints (it is hard to solder in the engine bay...) have you had any
experience with copper tape shielding? It seems like an obvious solution
rather than trying to solder behind the engine...
I will take a photo of the location of the former tach generator (or at
least what I think is the location...) and see what you think. Given
that both Jill and George have pre-manufactured plates, I will likely
get one from one of them and put that on.
Thanks again,
Scott
On 12-18-2010 13:33, Yak Pilot wrote:
> --> Yak-List message posted by: Yak Pilot<yakplt@yahoo.com>
>
> Hmmm!
>
> I need to add one step to my troubleshooting procedures Scott:
>
> Step Three: Have you added a digital tach that takes it's input off the P Leads.
If so, that is very high potential for noise addition to your aircraft.
>
> I actually thought of mentioning that, but since you did not bring it up in your
initial email, I guessed (incorrectly) that you had not modified anything
since you put in the new spark plugs and wire kit.
>
> To answer your question: When pulling the Tach Drive, most of the folks I know
have had a plate made that bolts on with the four corner bolts to the plate
and there you go. You make it yourself. You need to be very very careful here,
because if you remove the wrong "plate" you also will expose the gearing for
the tach drive that also is part of the air distributor drive. What I am saying
here is that if you pull the wrong plates and stuff in an attempt to put
a new cover plate over the tach drive, you can easily disturb the gearing inside,
which will in turn through your air start distributor out of adjustment and
then you are DEEP KIMSHEE! Re-timing the airstart distributor is NOT EASY
regardless of what anyone might tell you otherwise. So Scott, be very very careful
of what you take apart in that area. Without photo's it is hard for me
to describe what to take off and what not to take off. Talk to Dennis about tha
>
> --- On Fri, 12/17/10, Scott Poehlmann<scott-p@texas.net> wrote:
>
>> From: Scott Poehlmann<scott-p@texas.net>
>> Subject: Re: Yak-List: RF interference
>> To: yak-list@matronics.com
>> Date: Friday, December 17, 2010, 9:03 PM
>> --> Yak-List message posted by:
>> Scott Poehlmann<scott-p@texas.net>
>>
>> Thanks Mark,
>>
>> I knew that you would have a great, step by step method.
>>
>> Went out to the hangar today: looks like the P-leads are
>> the
>> culprit--BOTH have the shielding detached from the
>> connector and about 1
>> cm of unshielded lead "hanging in the breeze". I'll spend
>> some time
>> tomorrow AM soldering the shielding to the connector (it
>> appears that
>> this has been done before and that the solder joints have
>> failed...),
>> and will advise if this doesn't fix the problem.
>>
>> Now for the next question: any ideas where to find a cover
>> for the tach
>> generator drive? I am running a Horizon digital tach (which
>> takes its
>> data from the mag--in fact it is wired into the back of the
>> mag
>> switch...), and I have no tach generator, just a big open
>> fitting with a
>> drive (and seal) at the bottom... Threaded on the outside,
>> of course.
>>
>> Thanks again, and to everyone else who provided
>> information. This list
>> is a tremendous asset to the continued operation of these
>> airplanes.
>>
>> Scott
>>
>> On 12-17-2010 10:15, Yak Pilot wrote:
>>> --> Yak-List message posted by: Yak
>> Pilot<yakplt@yahoo.com>
>>> Do the following:
>>>
>>> Remove the plug from the Tach Gen and tie it back. Run
>> the aircraft. Does the noise go away? Then it is
>> indeed your Tach Gen and it is most likely shielding at the
>> Tach Generator plug itself. Be careful taking this
>> plug apart as it is common for the soldering on these wires
>> to break.
>>> If the noise does not go away, fly the airplane.
>> Over the airport come to complete idle and then shut the
>> mags off. Both mags, turn them off.
>>> You're now a glider.
>>>
>>> Did the noise go away? If it did, then you have
>> a MAG noise problem. The mag noise filters will help,
>> but before you go to that effort, look at the P leak plugs
>> that go into the side of the mags. It is very common
>> for people to twist these plugs off during some kind of
>> maint. action and in the process twist the shield right off
>> the plug as well. If the P Lead is unshielded you will
>> have one huge amount of noise.
>>> If the noise is still there even when you have
>> performed these steps (whcih is highly unlikely) then you've
>> got some other device radiating energy in the
>> aircraft. Start turning everything that you can off to
>> try and identify it.
>>> Suggestions have been made to see if it is coming in
>> via the antenna or the power wiring. I have posted
>> these suggestions before, but it is something you do at the
>> end of troubleshooting and not the beginning. It is
>> much easier to identify the noise source and eliminate it
>> where it is coming from. If you can't identify the
>> noise and you are lucky enough to have it coming in via the
>> power wires (again this is rare), a choke on the input power
>> wiring can help eliminate the noise. This can be as
>> simple as a snap on torroid, or an expensive (purchased)
>> filter, that is usually some sort of "Pi L brute force"
>> filter consisting of two caps and an inductor.
>> Usually, snap on torroids are just as effective and much
>> cheaper. Again though, noise coming in via the power
>> wiring is rare. It usually is coming in via the
>> antenna, and that means you MUST eliminate the noise at it's
>> source.
>>> The tests described above will usually nail the
>> problem in short order.
>>> Mark Bitterlich
>>>
>>> p.s. The reason I recommend shutting the mags
>> off at idle in flight versus doing it on the ground is
>> because the engine keeps wind-milling even with the mags
>> off, and you can leave them off much longer while you are
>> listening for radio noise and seeing if it goes away.
>> Shutting the engine off with the mags and the engine
>> windmilling with it at idle will not hurt anything, although
>> the engine will cool off really fast, so when you turn the
>> mags back on and the engine once again is actually
>> "running", don't just cob the power to 100%. Bring it
>> in slowly. Common sense applies.
>>> --- On Thu, 12/16/10, Roger Kemp M.D.<viperdoc@mindspring.com>
>> wrote:
>>>> From: Roger Kemp M.D.<viperdoc@mindspring.com>
>>>> Subject: RE: Yak-List: RF interference
>>>> To: yak-list@matronics.com
>>>> Date: Thursday, December 16, 2010, 1:35 PM
>>>> --> Yak-List message posted by:
>>>> "Roger Kemp M.D."<viperdoc@mindspring.com>
>>>>
>>>> Check the shielding on your Tac Generator. That is
>> the most
>>>> likely source
>>>> for RPM related noise.
>>>> Doc
>>>>
>>>> -----Original Message-----
>>>> From: owner-yak-list-server@matronics.com
>>>> [mailto:owner-yak-list-server@matronics.com]
>>>> On Behalf Of Scott Poehlmann
>>>> Sent: Thursday, December 16, 2010 5:07 AM
>>>> To: yak-list@matronics.com
>>>> Subject: Yak-List: RF interference
>>>>
>>>> --> Yak-List message posted by: Scott
>> Poehlmann<scott-p@texas.net>
>>>> Hi All,
>>>>
>>>> I am aware this has been discussed before, but as
>> the
>>>> problem now
>>>> effects my own airplane, I have am a bit more
>> attentive...
>>>> I have a Yak 55M with an auto-plug conversion.
>> The
>>>> conversion has been
>>>> in place for about 3 years now (roughly 400
>> hours). I am
>>>> now getting RF
>>>> interference picked up in the Briz radio from the
>> mags/plug
>>>> wires. At
>>>> least I assume that is the source, as it is RPM
>> dependent.
>>>> It has been
>>>> present since installation, but has been gradually
>> getting
>>>> worse over
>>>> the past year or so. I assume that there is a
>> shielding
>>>> issue either at
>>>> the mag connection or along the wires somewhere.
>> My
>>>> question to you is
>>>> where should I start to look at trouble shooting
>> this
>>>> issue, and how do
>>>> I go about fixing it (shy of completely replacing
>> the plug
>>>> wires, which
>>>> I'd prefer not to do... But will do if need
>> be...)?
>>>> Any thoughts you might have on the matter would
>> be
>>>> appreciated.
>>>>
>>>> Thanks,
>>>>
>>>> Scott Poehlmann
>>>> Yak 55M N155YK
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Lists This Month --
>>>> Some AWESOME FREE Gifts!)
>>>> Raiser. Click on
>>>> out more about
>>>> Gifts provided
>>>> www.aeroelectric.com
>>>> www.buildersbooks.com
>>>> www.homebuilthelp.com
>>>>
>> -Matt
>>>> Dralle, List Admin.
>>>> Forum -
>>>> FAQ,
>>>> - MATRONICS WEB FORUMS -
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>> Lists This Month --
>> Some AWESOME FREE Gifts!)
>> Raiser. Click on
>> out more about
>> Gifts provided
>> www.aeroelectric.com
>> www.buildersbooks.com
>> www.homebuilthelp.com
>> -Matt
>> Dralle, List Admin.
>> Forum -
>> FAQ,
>> - MATRONICS WEB FORUMS -
>>
>>
>>
>>
>
>
Message 7
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| Subject: | Re: RF interference |
Ahh.
Perhaps I should shield the wires to the tach, too. The interference
really does go away to essentially nothing (ok, I get an occasional
"pop" or two, but NOTHING like before) when running on just Mag 1 now,
so if I can accomplish the same thing with Mag 2, then I am happy.
Will look into the shielding on those wires after fixing P-lead on Mag
2, and report back.
Scott
On 12-18-2010 13:46, Yak Pilot wrote:
> --> Yak-List message posted by: Yak Pilot<yakplt@yahoo.com>
>
>
> Hmmm!
>
> I need to add one step to my troubleshooting procedures Scott:
>
> Step Three: Have you added a digital tach that takes it's input off the P Leads.
If so, that is very high potential for noise addition to your aircraft.
>
> I actually thought of mentioning that, but since you did not bring it up in your
initial email, I guessed (incorrectly) that you had not modified anything
since you put in the new spark plugs and wire kit.
>
> To answer your question: When pulling the Tach Drive, most of the folks I know
have had a plate made that bolts on with the four corner bolts to the plate
and there you go. You make it yourself. You need to be very very careful here,
because if you remove the wrong "plate" you also will expose the gearing for
the tach drive that also is part of the air distributor drive. What I am saying
here is that if you pull the wrong plates and stuff in an attempt to put
a new cover plate over the tach drive, you can easily disturb the gearing inside,
which will in turn through your air start distributor out of adjustment and
then you are DEEP KIMSHEE! Re-timing the airstart distributor is NOT EASY
regardless of what anyone might tell you otherwise. So Scott, be very very careful
of what you take apart in that area. Without photo's it is hard for me
to describe what to take off and what not to take off. Talk to Dennis about that
for details.
>
> Somehow I just managed to send this message when my fingers slipped on the keyboard
oops so here is the end of the message, sorry.
>
> Going back to your noise on your radios. I hate to tell you this Scott, but
those new digital tachs that attach to your P leads are a real source of radio
noise. This is the forth time I have had a person who installed that tach start
talking about radio noise. I also have personal experience with that thing
myself.
>
> Given that your Tach Generator is now removed from the aircraft, and you have
installed the Digital Tach that used your P leads for a input, I am 99.999% sure
that your new radio noise is from the P leads. Yes, you should repair the
shields down at the MAGs and that will help. But you also are going to have
to go back to the wires that have been attached behind the mag switch and make
darn sure that shielded wires were used there as well. Just leaving a tiny bit
of exposed wire (I.E. Where there is no shielding on the P leads) will allow
that to act as an antenna and RADIATE NOISE all over the aircraft.
>
> In one aircraft I worked on (a Sukhoi 26) I had to replace all of that wiring
to the digital tach, and then... get ready for this.. I had to make an actual
BOX out of aluminum and enclose the whole tach inside that box (a Faraday Shield
per se) and ground all that.
>
> So that is the downside of using that kind of Tach, I am sorry to have to say.
Its a GREAT TACH, and I love the way it works, but since it uses the P leads,
you have to really pay attention to your shielding. There is usually no filter
that can eliminate this kind of noise. Spark noise is very broad spectrum
and if you are anywhere in the near field from this noise, youre pretty much
screwed.
>
> One trick that SOMETIMES helps: Take a handheld VHF radio, remove the antenna
and stick a paperclip into the center conductor of the antenna jack. Hook headphones
to the handheld radio. Now start the aircraft and use the radio as
a test wand and run it around the wiring to try and find the source. This is
not easy and takes some effort.
>
> Bottom line: Your noise is coming from your P leads and new tach. Good luck.
Merry Christmas.
>
> Mark Bitterlich
>
>
> --- On Fri, 12/17/10, Scott Poehlmann<scott-p@texas.net> wrote:
>
>> From: Scott Poehlmann<scott-p@texas.net>
>> Subject: Re: Yak-List: RF interference
>> To: yak-list@matronics.com
>> Date: Friday, December 17, 2010, 9:03 PM
>> --> Yak-List message posted by:
>> Scott Poehlmann<scott-p@texas.net>
>>
>> Thanks Mark,
>>
>> I knew that you would have a great, step by step method.
>>
>> Went out to the hangar today: looks like the P-leads are
>> the
>> culprit--BOTH have the shielding detached from the
>> connector and about 1
>> cm of unshielded lead "hanging in the breeze". I'll spend
>> some time
>> tomorrow AM soldering the shielding to the connector (it
>> appears that
>> this has been done before and that the solder joints have
>> failed...),
>> and will advise if this doesn't fix the problem.
>>
>> Now for the next question: any ideas where to find a cover
>> for the tach
>> generator drive? I am running a Horizon digital tach (which
>> takes its
>> data from the mag--in fact it is wired into the back of the
>> mag
>> switch...), and I have no tach generator, just a big open
>> fitting with a
>> drive (and seal) at the bottom... Threaded on the outside,
>> of course.
>>
>> Thanks again, and to everyone else who provided
>> information. This list
>> is a tremendous asset to the continued operation of these
>> airplanes.
>>
>> Scott
>>
>> On 12-17-2010 10:15, Yak Pilot wrote:
>>> --> Yak-List message posted by: Yak
>> Pilot<yakplt@yahoo.com>
>>> Do the following:
>>>
>>> Remove the plug from the Tach Gen and tie it back. Run
>> the aircraft. Does the noise go away? Then it is
>> indeed your Tach Gen and it is most likely shielding at the
>> Tach Generator plug itself. Be careful taking this
>> plug apart as it is common for the soldering on these wires
>> to break.
>>> If the noise does not go away, fly the airplane.
>> Over the airport come to complete idle and then shut the
>> mags off. Both mags, turn them off.
>>> You're now a glider.
>>>
>>> Did the noise go away? If it did, then you have
>> a MAG noise problem. The mag noise filters will help,
>> but before you go to that effort, look at the P leak plugs
>> that go into the side of the mags. It is very common
>> for people to twist these plugs off during some kind of
>> maint. action and in the process twist the shield right off
>> the plug as well. If the P Lead is unshielded you will
>> have one huge amount of noise.
>>> If the noise is still there even when you have
>> performed these steps (whcih is highly unlikely) then you've
>> got some other device radiating energy in the
>> aircraft. Start turning everything that you can off to
>> try and identify it.
>>> Suggestions have been made to see if it is coming in
>> via the antenna or the power wiring. I have posted
>> these suggestions before, but it is something you do at the
>> end of troubleshooting and not the beginning. It is
>> much easier to identify the noise source and eliminate it
>> where it is coming from. If you can't identify the
>> noise and you are lucky enough to have it coming in via the
>> power wires (again this is rare), a choke on the input power
>> wiring can help eliminate the noise. This can be as
>> simple as a snap on torroid, or an expensive (purchased)
>> filter, that is usually some sort of "Pi L brute force"
>> filter consisting of two caps and an inductor.
>> Usually, snap on torroids are just as effective and much
>> cheaper. Again though, noise coming in via the power
>> wiring is rare. It usually is coming in via the
>> antenna, and that means you MUST eliminate the noise at it's
>> source.
>>> The tests described above will usually nail the
>> problem in short order.
>>> Mark Bitterlich
>>>
>>> p.s. The reason I recommend shutting the mags
>> off at idle in flight versus doing it on the ground is
>> because the engine keeps wind-milling even with the mags
>> off, and you can leave them off much longer while you are
>> listening for radio noise and seeing if it goes away.
>> Shutting the engine off with the mags and the engine
>> windmilling with it at idle will not hurt anything, although
>> the engine will cool off really fast, so when you turn the
>> mags back on and the engine once again is actually
>> "running", don't just cob the power to 100%. Bring it
>> in slowly. Common sense applies.
>>> --- On Thu, 12/16/10, Roger Kemp M.D.<viperdoc@mindspring.com>
>> wrote:
>>>> From: Roger Kemp M.D.<viperdoc@mindspring.com>
>>>> Subject: RE: Yak-List: RF interference
>>>> To: yak-list@matronics.com
>>>> Date: Thursday, December 16, 2010, 1:35 PM
>>>> --> Yak-List message posted by:
>>>> "Roger Kemp M.D."<viperdoc@mindspring.com>
>>>>
>>>> Check the shielding on your Tac Generator. That is
>> the most
>>>> likely source
>>>> for RPM related noise.
>>>> Doc
>>>>
>>>> -----Original Message-----
>>>> From: owner-yak-list-server@matronics.com
>>>> [mailto:owner-yak-list-server@matronics.com]
>>>> On Behalf Of Scott Poehlmann
>>>> Sent: Thursday, December 16, 2010 5:07 AM
>>>> To: yak-list@matronics.com
>>>> Subject: Yak-List: RF interference
>>>>
>>>> --> Yak-List message posted by: Scott
>> Poehlmann<scott-p@texas.net>
>>>> Hi All,
>>>>
>>>> I am aware this has been discussed before, but as
>> the
>>>> problem now
>>>> effects my own airplane, I have am a bit more
>> attentive...
>>>> I have a Yak 55M with an auto-plug conversion.
>> The
>>>> conversion has been
>>>> in place for about 3 years now (roughly 400
>> hours). I am
>>>> now getting RF
>>>> interference picked up in the Briz radio from the
>> mags/plug
>>>> wires. At
>>>> least I assume that is the source, as it is RPM
>> dependent.
>>>> It has been
>>>> present since installation, but has been gradually
>> getting
>>>> worse over
>>>> the past year or so. I assume that there is a
>> shielding
>>>> issue either at
>>>> the mag connection or along the wires somewhere.
>> My
>>>> question to you is
>>>> where should I start to look at trouble shooting
>> this
>>>> issue, and how do
>>>> I go about fixing it (shy of completely replacing
>> the plug
>>>> wires, which
>>>> I'd prefer not to do... But will do if need
>> be...)?
>>>> Any thoughts you might have on the matter would
>> be
>>>> appreciated.
>>>>
>>>> Thanks,
>>>>
>>>> Scott Poehlmann
>>>> Yak 55M N155YK
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Lists This Month --
>>>> Some AWESOME FREE Gifts!)
>>>> Raiser. Click on
>>>> out more about
>>>> Gifts provided
>>>> www.aeroelectric.com
>>>> www.buildersbooks.com
>>>> www.homebuilthelp.com
>>>>
>> -Matt
>>>> Dralle, List Admin.
>>>> Forum -
>>>> FAQ,
>>>> - MATRONICS WEB FORUMS -
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>> Lists This Month --
>> Some AWESOME FREE Gifts!)
>> Raiser. Click on
>> out more about
>> Gifts provided
>> www.aeroelectric.com
>> www.buildersbooks.com
>> www.homebuilthelp.com
>> -Matt
>> Dralle, List Admin.
>> Forum -
>> FAQ,
>> - MATRONICS WEB FORUMS -
>>
>>
>>
>>
>
>
Message 8
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|
| Subject: | Re: RF interference |
Scott,
Any wire at all that hooks to the P lead of any mag is a noise source. Period.
How much it will influence the radio is an open question. Many folks that are
unfamiliar with radio theory think that radio interference is something you
can hear in your headset. Not necessarily the case at all.
But the bottom line is always the bottom line. If you as the pilot feel that your
radio is performing well enough for you to be happy with it, that is all that
really matters in the end.
I am not sure why you are having such a difficult time soldering the P lead wiring,
but then ... I am not there looking at it. Normally you can remove some
clamps and tie-ties (or whatever) and have plenty of slack available to be able
to get that plug out into the open. If you try to solder it without taking
the time to remove all that junk so that you have some slack, you're right, it
can be miserable.
Typically, I have had to re-do the whole P lead connector, by unsoldering the center
conductor from the metal piece, cutting it back and starting from scratch.
Just be aware... anything at all attached to a P lead that is unshielded is going
to radiate energy. How much and where and if you can accept it, is of course
a decision that must be made by you.
Plate: Get one from Jill and then you can see exactly which one that is already
on there that you have to remove in order to put the new plate on.
Take care,
Mark
--- On Sat, 12/18/10, Scott Poehlmann <scott-p@texas.net> wrote:
> From: Scott Poehlmann <scott-p@texas.net>
> Subject: Re: Yak-List: RF interference
> To: yak-list@matronics.com
> Date: Saturday, December 18, 2010, 5:32 PM
> Scott Poehlmann <scott-p@texas.net>
>
> Thanks Mark,
>
> I didn't mention the tach because, frankly, I didn't think
> about it. The
> tach appears to be wired at the mag switch, and and that
> cabling is
> unshielded. I don't know if that is at issue or not, but
> given what
> happened today, I think not...
>
> Having said that, I am 98% certain I have found the
> problem. I soldered
> the shield back on the right (#1) mag and now I have the
> problem only
> when the left (#2) mag is operating (i.e., position "2" and
> "1+2"). I
> will repeat the process with the left mag tomorrow, and I
> suspect that I
> am done. I am not particularly happy with the quality of
> the solder
> joints (it is hard to solder in the engine bay...) have you
> had any
> experience with copper tape shielding? It seems like an
> obvious solution
> rather than trying to solder behind the engine...
>
> I will take a photo of the location of the former tach
> generator (or at
> least what I think is the location...) and see what you
> think. Given
> that both Jill and George have pre-manufactured plates, I
> will likely
> get one from one of them and put that on.
>
> Thanks again,
>
> Scott
>
> On 12-18-2010 13:33, Yak Pilot wrote:
> Pilot<yakplt@yahoo.com>
> >
> > Hmmm!
> >
> > I need to add one step to my troubleshooting
> procedures Scott:
> >
> > Step Three: Have you added a digital tach that
> takes it's input off the P Leads. If so, that is very
> high potential for noise addition to your aircraft.
> >
> > I actually thought of mentioning that, but since you
> did not bring it up in your initial email, I guessed
> (incorrectly) that you had not modified anything since you
> put in the new spark plugs and wire kit.
> >
> > To answer your question: When pulling the Tach
> Drive, most of the folks I know have had a plate made that
> bolts on with the four corner bolts to the plate and there
> you go. You make it yourself. You need to be
> very very careful here, because if you remove the wrong
> "plate" you also will expose the gearing for the tach drive
> that also is part of the air distributor drive. What I
> am saying here is that if you pull the wrong plates and
> stuff in an attempt to put a new cover plate over the tach
> drive, you can easily disturb the gearing inside, which will
> in turn through your air start distributor out of adjustment
> and then you are DEEP KIMSHEE! Re-timing the airstart
> distributor is NOT EASY regardless of what anyone might tell
> you otherwise. So Scott, be very very careful of what
> you take apart in that area. Without photo's it is
> hard for me to describe what to take off and what not to
> take off. Talk to Dennis about tha
> >
> > --- On Fri, 12/17/10, Scott Poehlmann<scott-p@texas.net>
> wrote:
> >
> >> From: Scott Poehlmann<scott-p@texas.net>
> >> Subject: Re: Yak-List: RF interference
> >> To: yak-list@matronics.com
> >> Date: Friday, December 17, 2010, 9:03 PM
> >> Scott Poehlmann<scott-p@texas.net>
> >>
> >> Thanks Mark,
> >>
> >> I knew that you would have a great, step by step
> method.
> >>
> >> Went out to the hangar today: looks like the
> P-leads are
> >> the
> >> culprit--BOTH have the shielding detached from
> the
> >> connector and about 1
> >> cm of unshielded lead "hanging in the breeze".
> I'll spend
> >> some time
> >> tomorrow AM soldering the shielding to the
> connector (it
> >> appears that
> >> this has been done before and that the solder
> joints have
> >> failed...),
> >> and will advise if this doesn't fix the problem.
> >>
> >> Now for the next question: any ideas where to find
> a cover
> >> for the tach
> >> generator drive? I am running a Horizon digital
> tach (which
> >> takes its
> >> data from the mag--in fact it is wired into the
> back of the
> >> mag
> >> switch...), and I have no tach generator, just a
> big open
> >> fitting with a
> >> drive (and seal) at the bottom... Threaded on the
> outside,
> >> of course.
> >>
> >> Thanks again, and to everyone else who provided
> >> information. This list
> >> is a tremendous asset to the continued operation
> of these
> >> airplanes.
> >>
> >> Scott
> >>
> >> On 12-17-2010 10:15, Yak Pilot wrote:
> >>> -->Yak-List message
> posted by: Yak
> >> Pilot<yakplt@yahoo.com>
> >>> Do the following:
> >>>
> >>> Remove the plug from the Tach Gen and tie it
> back. Run
> >> the aircraft. Does the noise go away?
> Then it is
> >> indeed your Tach Gen and it is most likely
> shielding at the
> >> Tach Generator plug itself. Be careful
> taking this
> >> plug apart as it is common for the soldering on
> these wires
> >> to break.
> >>> If the noise does not go away, fly the
> airplane.
> >> Over the airport come to complete idle and then
> shut the
> >> mags off. Both mags, turn them off.
> >>> You're now a glider.
> >>>
> >>> Did the noise go away? If it did, then
> you have
> >> a MAG noise problem. The mag noise filters
> will help,
> >> but before you go to that effort, look at the P
> leak plugs
> >> that go into the side of the mags. It is
> very common
> >> for people to twist these plugs off during some
> kind of
> >> maint. action and in the process twist the shield
> right off
> >> the plug as well. If the P Lead is
> unshielded you will
> >> have one huge amount of noise.
> >>> If the noise is still there even when you
> have
> >> performed these steps (whcih is highly unlikely)
> then you've
> >> got some other device radiating energy in the
> >> aircraft. Start turning everything that you
> can off to
> >> try and identify it.
> >>> Suggestions have been made to see if it is
> coming in
> >> via the antenna or the power wiring. I have
> posted
> >> these suggestions before, but it is something you
> do at the
> >> end of troubleshooting and not the
> beginning. It is
> >> much easier to identify the noise source and
> eliminate it
> >> where it is coming from. If you can't
> identify the
> >> noise and you are lucky enough to have it coming
> in via the
> >> power wires (again this is rare), a choke on the
> input power
> >> wiring can help eliminate the noise. This
> can be as
> >> simple as a snap on torroid, or an expensive
> (purchased)
> >> filter, that is usually some sort of "Pi L brute
> force"
> >> filter consisting of two caps and an inductor.
> >> Usually, snap on torroids are just as effective
> and much
> >> cheaper. Again though, noise coming in via
> the power
> >> wiring is rare. It usually is coming in via
> the
> >> antenna, and that means you MUST eliminate the
> noise at it's
> >> source.
> >>> The tests described above will usually nail
> the
> >> problem in short order.
> >>> Mark Bitterlich
> >>>
> >>> p.s. The reason I recommend shutting the
> mags
> >> off at idle in flight versus doing it on the
> ground is
> >> because the engine keeps wind-milling even with
> the mags
> >> off, and you can leave them off much longer while
> you are
> >> listening for radio noise and seeing if it goes
> away.
> >> Shutting the engine off with the mags and the
> engine
> >> windmilling with it at idle will not hurt
> anything, although
> >> the engine will cool off really fast, so when you
> turn the
> >> mags back on and the engine once again is
> actually
> >> "running", don't just cob the power to 100%.
> Bring it
> >> in slowly. Common sense applies.
> >>> --- On Thu, 12/16/10, Roger Kemp M.D.<viperdoc@mindspring.com>
> >> wrote:
> >>>> From: Roger Kemp M.D.<viperdoc@mindspring.com>
> >>>> Subject: RE: Yak-List: RF interference
> >>>> To: yak-list@matronics.com
> >>>> Date: Thursday, December 16, 2010, 1:35
> PM
> >>>> -->Yak-List message
> posted by:
> >>>> "Roger Kemp M.D."<viperdoc@mindspring.com>
> >>>>
> >>>> Check the shielding on your Tac Generator.
> That is
> >> the most
> >>>> likely source
> >>>> for RPM related noise.
> >>>> Doc
> >>>>
> >>>> -----Original Message-----
> >>>> From: owner-yak-list-server@matronics.com
> >>>> [mailto:owner-yak-list-server@matronics.com]
> >>>> On Behalf Of Scott Poehlmann
> >>>> Sent: Thursday, December 16, 2010 5:07 AM
> >>>> To: yak-list@matronics.com
> >>>> Subject: Yak-List: RF interference
> >>>>
> >>>> -->Yak-List message
> posted by: Scott
> >> Poehlmann<scott-p@texas.net>
> >>>> Hi All,
> >>>>
> >>>> I am aware this has been discussed before,
> but as
> >> the
> >>>> problem now
> >>>> effects my own airplane, I have am a bit
> more
> >> attentive...
> >>>> I have a Yak 55M with an auto-plug
> conversion.
> >> The
> >>>> conversion has been
> >>>> in place for about 3 years now (roughly
> 400
> >> hours). I am
> >>>> now getting RF
> >>>> interference picked up in the Briz radio
> from the
> >> mags/plug
> >>>> wires. At
> >>>> least I assume that is the source, as it
> is RPM
> >> dependent.
> >>>> It has been
> >>>> present since installation, but has been
> gradually
> >> getting
> >>>> worse over
> >>>> the past year or so. I assume that there
> is a
> >> shielding
> >>>> issue either at
> >>>> the mag connection or along the wires
> somewhere.
> >> My
> >>>> question to you is
> >>>> where should I start to look at trouble
> shooting
> >> this
> >>>> issue, and how do
> >>>> I go about fixing it (shy of completely
> replacing
> >> the plug
> >>>> wires, which
> >>>> I'd prefer not to do... But will do if
> need
> >> be...)?
> >>>> Any thoughts you might have on the matter
> would
> >> be
> >>>> appreciated.
> >>>>
> >>>> Thanks,
> >>>>
> >>>> Scott Poehlmann
> >>>> Yak 55M N155YK
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> Lists This Month --
> >>>> Some AWESOME FREE Gifts!)
> >>>> Raiser. Click on
> >>>> out more about
> >>>> Gifts provided
> >>>> www.aeroelectric.com
> >>>> www.buildersbooks.com
> >>>> www.homebuilthelp.com
> >>>>
> >> -Matt
> >>>> Dralle, List Admin.
> >>>> Forum -
> >>>> FAQ,
> >>>> - MATRONICS
> WEB FORUMS -
> >>>>
> >>>>
> >>>>
> >>>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>
> >> Lists This Month --
> >> Some AWESOME FREE Gifts!)
> >> Raiser. Click on
> >> out more about
> >> Gifts provided
> >> www.aeroelectric.com
> >> www.buildersbooks.com
> >> www.homebuilthelp.com
> >>
> -Matt
> >> Dralle, List Admin.
> >> Forum -
> >> FAQ,
> >> - MATRONICS WEB FORUMS -
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
> Lists This Month --
> Some AWESOME FREE Gifts!)
> Raiser. Click on
> out more about
> Gifts provided
> www.aeroelectric.com
> www.buildersbooks.com
> www.homebuilthelp.com
> -Matt
> Dralle, List Admin.
> Forum -
> FAQ,
> - MATRONICS WEB FORUMS -
>
>
>
>
Message 9
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| Subject: | Re: RF interference |
Scott, without going into a long discussion on how radios work, the simple fact
is that you can not determine how much interference you are getting simply by
plugging in the headset and listening for noise. Without using test equipment
it is sometimes hard to quantify.
However, there are some simple tests that allow the human ear to determine if you
are being impacted by it or not.
The most simple test is to tune the radio to a really weak signal that is just
barely readable, and then start the engine and see how the noise impacts the reception
of that signal. That can be hard to do at the airport where most RF
sources are right there on the field. This test will only work if you can tune
into a signal that is already right on the threshold of detection. If you can
do that now, great. If not, you need a sig-gen and somebody who knows how
to use it.
Failing that, go fly and tune your radio into some ASOS or ATIS transmission a
long way aways and listen to them. Then turn off the mags and see how much the
signal improves. If it does, then you need to attack your shielding more vigorously.
If turning the engine off with the mag switch does not impact your
weak received signal at all, then you have done as much as you can to shield P
leads. Crude but it will work..
Mark Bitterlich
--- On Sat, 12/18/10, Scott Poehlmann <scott-p@texas.net> wrote:
> From: Scott Poehlmann <scott-p@texas.net>
> Subject: Re: Yak-List: RF interference
> To: yak-list@matronics.com
> Date: Saturday, December 18, 2010, 5:37 PM
> Scott Poehlmann <scott-p@texas.net>
>
> Ahh.
>
> Perhaps I should shield the wires to the tach, too.
> The interference
> really does go away to essentially nothing (ok, I get an
> occasional
> "pop" or two, but NOTHING like before) when running on just
> Mag 1 now,
> so if I can accomplish the same thing with Mag 2, then I am
> happy.
>
> Will look into the shielding on those wires after fixing
> P-lead on Mag
> 2, and report back.
>
> Scott
>
> On 12-18-2010 13:46, Yak Pilot wrote:
> Pilot<yakplt@yahoo.com>
> >
> >
> > Hmmm!
> >
> > I need to add one step to my troubleshooting
> procedures Scott:
> >
> > Step Three: Have you added a digital tach that
> takes it's input off the P Leads. If so, that is very
> high potential for noise addition to your aircraft.
> >
> > I actually thought of mentioning that, but since you
> did not bring it up in your initial email, I guessed
> (incorrectly) that you had not modified anything since you
> put in the new spark plugs and wire kit.
> >
> > To answer your question: When pulling the Tach
> Drive, most of the folks I know have had a plate made that
> bolts on with the four corner bolts to the plate and there
> you go. You make it yourself. You need to be
> very very careful here, because if you remove the wrong
> "plate" you also will expose the gearing for the tach drive
> that also is part of the air distributor drive. What I
> am saying here is that if you pull the wrong plates and
> stuff in an attempt to put a new cover plate over the tach
> drive, you can easily disturb the gearing inside, which will
> in turn through your air start distributor out of adjustment
> and then you are DEEP KIMSHEE! Re-timing the airstart
> distributor is NOT EASY regardless of what anyone might tell
> you otherwise. So Scott, be very very careful of what
> you take apart in that area. Without photo's it is
> hard for me to describe what to take off and what not to
> take off. Talk to Dennis about that for details.
> >
> > Somehow I just managed to send this message when my
> fingers slipped on the keyboard oops so here is the
> end of the message, sorry.
> >
> > Going back to your noise on your radios. I hate
> to tell you this Scott, but those new digital tachs that
> attach to your P leads are a real source of radio
> noise. This is the forth time I have had a person who
> installed that tach start talking about radio noise. I
> also have personal experience with that thing myself.
> >
> > Given that your Tach Generator is now removed from the
> aircraft, and you have installed the Digital Tach that used
> your P leads for a input, I am 99.999% sure that your new
> radio noise is from the P leads. Yes, you should
> repair the shields down at the MAGs and that will
> help. But you also are going to have to go back to the
> wires that have been attached behind the mag switch and make
> darn sure that shielded wires were used there as well.
> Just leaving a tiny bit of exposed wire (I.E. Where there is
> no shielding on the P leads) will allow that to act as an
> antenna and RADIATE NOISE all over the aircraft.
> >
> > In one aircraft I worked on (a Sukhoi 26) I had to
> replace all of that wiring to the digital tach, and then...
> get ready for this.. I had to make an actual BOX out of
> aluminum and enclose the whole tach inside that box (a
> Faraday Shield per se) and ground all that.
> >
> > So that is the downside of using that kind of Tach, I
> am sorry to have to say. Its a GREAT TACH, and I
> love the way it works, but since it uses the P leads, you
> have to really pay attention to your shielding. There
> is usually no filter that can eliminate this kind of
> noise. Spark noise is very broad spectrum and if you
> are anywhere in the near field from this noise, youre
> pretty much screwed.
> >
> > One trick that SOMETIMES helps: Take a handheld
> VHF radio, remove the antenna and stick a paperclip into the
> center conductor of the antenna jack. Hook headphones
> to the handheld radio. Now start the aircraft and use
> the radio as a test wand and run it around the wiring
> to try and find the source. This is not easy and takes
> some effort.
> >
> > Bottom line: Your noise is coming from your P
> leads and new tach. Good luck. Merry Christmas.
> >
> > Mark Bitterlich
> >
> >
> > --- On Fri, 12/17/10, Scott Poehlmann<scott-p@texas.net>
> wrote:
> >
> >> From: Scott Poehlmann<scott-p@texas.net>
> >> Subject: Re: Yak-List: RF interference
> >> To: yak-list@matronics.com
> >> Date: Friday, December 17, 2010, 9:03 PM
> >> Scott Poehlmann<scott-p@texas.net>
> >>
> >> Thanks Mark,
> >>
> >> I knew that you would have a great, step by step
> method.
> >>
> >> Went out to the hangar today: looks like the
> P-leads are
> >> the
> >> culprit--BOTH have the shielding detached from
> the
> >> connector and about 1
> >> cm of unshielded lead "hanging in the breeze".
> I'll spend
> >> some time
> >> tomorrow AM soldering the shielding to the
> connector (it
> >> appears that
> >> this has been done before and that the solder
> joints have
> >> failed...),
> >> and will advise if this doesn't fix the problem.
> >>
> >> Now for the next question: any ideas where to find
> a cover
> >> for the tach
> >> generator drive? I am running a Horizon digital
> tach (which
> >> takes its
> >> data from the mag--in fact it is wired into the
> back of the
> >> mag
> >> switch...), and I have no tach generator, just a
> big open
> >> fitting with a
> >> drive (and seal) at the bottom... Threaded on the
> outside,
> >> of course.
> >>
> >> Thanks again, and to everyone else who provided
> >> information. This list
> >> is a tremendous asset to the continued operation
> of these
> >> airplanes.
> >>
> >> Scott
> >>
> >> On 12-17-2010 10:15, Yak Pilot wrote:
> >>> -->Yak-List message
> posted by: Yak
> >> Pilot<yakplt@yahoo.com>
> >>> Do the following:
> >>>
> >>> Remove the plug from the Tach Gen and tie it
> back. Run
> >> the aircraft. Does the noise go away?
> Then it is
> >> indeed your Tach Gen and it is most likely
> shielding at the
> >> Tach Generator plug itself. Be careful
> taking this
> >> plug apart as it is common for the soldering on
> these wires
> >> to break.
> >>> If the noise does not go away, fly the
> airplane.
> >> Over the airport come to complete idle and then
> shut the
> >> mags off. Both mags, turn them off.
> >>> You're now a glider.
> >>>
> >>> Did the noise go away? If it did, then
> you have
> >> a MAG noise problem. The mag noise filters
> will help,
> >> but before you go to that effort, look at the P
> leak plugs
> >> that go into the side of the mags. It is
> very common
> >> for people to twist these plugs off during some
> kind of
> >> maint. action and in the process twist the shield
> right off
> >> the plug as well. If the P Lead is
> unshielded you will
> >> have one huge amount of noise.
> >>> If the noise is still there even when you
> have
> >> performed these steps (whcih is highly unlikely)
> then you've
> >> got some other device radiating energy in the
> >> aircraft. Start turning everything that you
> can off to
> >> try and identify it.
> >>> Suggestions have been made to see if it is
> coming in
> >> via the antenna or the power wiring. I have
> posted
> >> these suggestions before, but it is something you
> do at the
> >> end of troubleshooting and not the
> beginning. It is
> >> much easier to identify the noise source and
> eliminate it
> >> where it is coming from. If you can't
> identify the
> >> noise and you are lucky enough to have it coming
> in via the
> >> power wires (again this is rare), a choke on the
> input power
> >> wiring can help eliminate the noise. This
> can be as
> >> simple as a snap on torroid, or an expensive
> (purchased)
> >> filter, that is usually some sort of "Pi L brute
> force"
> >> filter consisting of two caps and an inductor.
> >> Usually, snap on torroids are just as effective
> and much
> >> cheaper. Again though, noise coming in via
> the power
> >> wiring is rare. It usually is coming in via
> the
> >> antenna, and that means you MUST eliminate the
> noise at it's
> >> source.
> >>> The tests described above will usually nail
> the
> >> problem in short order.
> >>> Mark Bitterlich
> >>>
> >>> p.s. The reason I recommend shutting the
> mags
> >> off at idle in flight versus doing it on the
> ground is
> >> because the engine keeps wind-milling even with
> the mags
> >> off, and you can leave them off much longer while
> you are
> >> listening for radio noise and seeing if it goes
> away.
> >> Shutting the engine off with the mags and the
> engine
> >> windmilling with it at idle will not hurt
> anything, although
> >> the engine will cool off really fast, so when you
> turn the
> >> mags back on and the engine once again is
> actually
> >> "running", don't just cob the power to 100%.
> Bring it
> >> in slowly. Common sense applies.
> >>> --- On Thu, 12/16/10, Roger Kemp M.D.<viperdoc@mindspring.com>
> >> wrote:
> >>>> From: Roger Kemp M.D.<viperdoc@mindspring.com>
> >>>> Subject: RE: Yak-List: RF interference
> >>>> To: yak-list@matronics.com
> >>>> Date: Thursday, December 16, 2010, 1:35
> PM
> >>>> -->Yak-List message
> posted by:
> >>>> "Roger Kemp M.D."<viperdoc@mindspring.com>
> >>>>
> >>>> Check the shielding on your Tac Generator.
> That is
> >> the most
> >>>> likely source
> >>>> for RPM related noise.
> >>>> Doc
> >>>>
> >>>> -----Original Message-----
> >>>> From: owner-yak-list-server@matronics.com
> >>>> [mailto:owner-yak-list-server@matronics.com]
> >>>> On Behalf Of Scott Poehlmann
> >>>> Sent: Thursday, December 16, 2010 5:07 AM
> >>>> To: yak-list@matronics.com
> >>>> Subject: Yak-List: RF interference
> >>>>
> >>>> -->Yak-List message
> posted by: Scott
> >> Poehlmann<scott-p@texas.net>
> >>>> Hi All,
> >>>>
> >>>> I am aware this has been discussed before,
> but as
> >> the
> >>>> problem now
> >>>> effects my own airplane, I have am a bit
> more
> >> attentive...
> >>>> I have a Yak 55M with an auto-plug
> conversion.
> >> The
> >>>> conversion has been
> >>>> in place for about 3 years now (roughly
> 400
> >> hours). I am
> >>>> now getting RF
> >>>> interference picked up in the Briz radio
> from the
> >> mags/plug
> >>>> wires. At
> >>>> least I assume that is the source, as it
> is RPM
> >> dependent.
> >>>> It has been
> >>>> present since installation, but has been
> gradually
> >> getting
> >>>> worse over
> >>>> the past year or so. I assume that there
> is a
> >> shielding
> >>>> issue either at
> >>>> the mag connection or along the wires
> somewhere.
> >> My
> >>>> question to you is
> >>>> where should I start to look at trouble
> shooting
> >> this
> >>>> issue, and how do
> >>>> I go about fixing it (shy of completely
> replacing
> >> the plug
> >>>> wires, which
> >>>> I'd prefer not to do... But will do if
> need
> >> be...)?
> >>>> Any thoughts you might have on the matter
> would
> >> be
> >>>> appreciated.
> >>>>
> >>>> Thanks,
> >>>>
> >>>> Scott Poehlmann
> >>>> Yak 55M N155YK
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> Lists This Month --
> >>>> Some AWESOME FREE Gifts!)
> >>>> Raiser. Click on
> >>>> out more about
> >>>> Gifts provided
> >>>> www.aeroelectric.com
> >>>> www.buildersbooks.com
> >>>> www.homebuilthelp.com
> >>>>
> >> -Matt
> >>>> Dralle, List Admin.
> >>>> Forum -
> >>>> FAQ,
> >>>> - MATRONICS
> WEB FORUMS -
> >>>>
> >>>>
> >>>>
> >>>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>
> >> Lists This Month --
> >> Some AWESOME FREE Gifts!)
> >> Raiser. Click on
> >> out more about
> >> Gifts provided
> >> www.aeroelectric.com
> >> www.buildersbooks.com
> >> www.homebuilthelp.com
> >>
> -Matt
> >> Dralle, List Admin.
> >> Forum -
> >> FAQ,
> >> - MATRONICS WEB FORUMS -
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
> Lists This Month --
> Some AWESOME FREE Gifts!)
> Raiser. Click on
> out more about
> Gifts provided
> www.aeroelectric.com
> www.buildersbooks.com
> www.homebuilthelp.com
> -Matt
> Dralle, List Admin.
> Forum -
> FAQ,
> - MATRONICS WEB FORUMS -
>
>
>
>
Message 10
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| Subject: | Re: RF interference |
Hi Mark,
Of course this all makes sense, and you are right. Fortunately I have
such a source readily available... the ATIS on the field at ELP is 11 NM
away--straight LOS through a mountain. Under good circumstances it is
just audible on my field (when the Mexican cell phones are playing
tricks, it isn't audible at all, but that's another story...), so I can
use that for the test you propose. I don't have access to a signal
generator, nor do I have any interest in trying to mess with it beyond
that which is required to obtain good communication in both directions.
I am just happy it is something straightforward and not in the power
system. I was not looking forward to that job. Frankly, shielding the
wires from the mag switch to the tach should be easy (it's all behind
the panel with a total run of less than 2 feet). Now the question which
end to ground, and to what? Do you know if the housing of the mag switch
will tolerate being grounded (perhaps it already IS grounded?) or does
it need to "float"?
Thanks,
Scott
On 12-18-2010 17:31, Yak Pilot wrote:
> --> Yak-List message posted by: Yak Pilot<yakplt@yahoo.com>
>
> Scott, without going into a long discussion on how radios work, the simple fact
is that you can not determine how much interference you are getting simply
by plugging in the headset and listening for noise. Without using test equipment
it is sometimes hard to quantify.
>
> However, there are some simple tests that allow the human ear to determine if
you are being impacted by it or not.
>
> The most simple test is to tune the radio to a really weak signal that is just
barely readable, and then start the engine and see how the noise impacts the
reception of that signal. That can be hard to do at the airport where most RF
sources are right there on the field. This test will only work if you can tune
into a signal that is already right on the threshold of detection. If you
can do that now, great. If not, you need a sig-gen and somebody who knows how
to use it.
>
> Failing that, go fly and tune your radio into some ASOS or ATIS transmission
a long way aways and listen to them. Then turn off the mags and see how much
the signal improves. If it does, then you need to attack your shielding more
vigorously. If turning the engine off with the mag switch does not impact your
weak received signal at all, then you have done as much as you can to shield
P leads. Crude but it will work..
>
> Mark Bitterlich
>
>
> --- On Sat, 12/18/10, Scott Poehlmann<scott-p@texas.net> wrote:
>
>> From: Scott Poehlmann<scott-p@texas.net>
>> Subject: Re: Yak-List: RF interference
>> To: yak-list@matronics.com
>> Date: Saturday, December 18, 2010, 5:37 PM
>> --> Yak-List message posted by:
>> Scott Poehlmann<scott-p@texas.net>
>>
>> Ahh.
>>
>> Perhaps I should shield the wires to the tach, too.
>> The interference
>> really does go away to essentially nothing (ok, I get an
>> occasional
>> "pop" or two, but NOTHING like before) when running on just
>> Mag 1 now,
>> so if I can accomplish the same thing with Mag 2, then I am
>> happy.
>>
>> Will look into the shielding on those wires after fixing
>> P-lead on Mag
>> 2, and report back.
>>
>> Scott
>>
>> On 12-18-2010 13:46, Yak Pilot wrote:
>>> --> Yak-List message posted by: Yak
>> Pilot<yakplt@yahoo.com>
>>>
>>> Hmmm!
>>>
>>> I need to add one step to my troubleshooting
>> procedures Scott:
>>> Step Three: Have you added a digital tach that
>> takes it's input off the P Leads. If so, that is very
>> high potential for noise addition to your aircraft.
>>> I actually thought of mentioning that, but since you
>> did not bring it up in your initial email, I guessed
>> (incorrectly) that you had not modified anything since you
>> put in the new spark plugs and wire kit.
>>> To answer your question: When pulling the Tach
>> Drive, most of the folks I know have had a plate made that
>> bolts on with the four corner bolts to the plate and there
>> you go. You make it yourself. You need to be
>> very very careful here, because if you remove the wrong
>> "plate" you also will expose the gearing for the tach drive
>> that also is part of the air distributor drive. What I
>> am saying here is that if you pull the wrong plates and
>> stuff in an attempt to put a new cover plate over the tach
>> drive, you can easily disturb the gearing inside, which will
>> in turn through your air start distributor out of adjustment
>> and then you are DEEP KIMSHEE! Re-timing the airstart
>> distributor is NOT EASY regardless of what anyone might tell
>> you otherwise. So Scott, be very very careful of what
>> you take apart in that area. Without photo's it is
>> hard for me to describe what to take off and what not to
>> take off. Talk to Dennis about that for details.
>>> Somehow I just managed to send this message when my
>> fingers slipped on the keyboard oops so here is the
>> end of the message, sorry.
>>> Going back to your noise on your radios. I hate
>> to tell you this Scott, but those new digital tachs that
>> attach to your P leads are a real source of radio
>> noise. This is the forth time I have had a person who
>> installed that tach start talking about radio noise. I
>> also have personal experience with that thing myself.
>>> Given that your Tach Generator is now removed from the
>> aircraft, and you have installed the Digital Tach that used
>> your P leads for a input, I am 99.999% sure that your new
>> radio noise is from the P leads. Yes, you should
>> repair the shields down at the MAGs and that will
>> help. But you also are going to have to go back to the
>> wires that have been attached behind the mag switch and make
>> darn sure that shielded wires were used there as well.
>> Just leaving a tiny bit of exposed wire (I.E. Where there is
>> no shielding on the P leads) will allow that to act as an
>> antenna and RADIATE NOISE all over the aircraft.
>>> In one aircraft I worked on (a Sukhoi 26) I had to
>> replace all of that wiring to the digital tach, and then...
>> get ready for this.. I had to make an actual BOX out of
>> aluminum and enclose the whole tach inside that box (a
>> Faraday Shield per se) and ground all that.
>>> So that is the downside of using that kind of Tach, I
>> am sorry to have to say. Its a GREAT TACH, and I
>> love the way it works, but since it uses the P leads, you
>> have to really pay attention to your shielding. There
>> is usually no filter that can eliminate this kind of
>> noise. Spark noise is very broad spectrum and if you
>> are anywhere in the near field from this noise, youre
>> pretty much screwed.
>>> One trick that SOMETIMES helps: Take a handheld
>> VHF radio, remove the antenna and stick a paperclip into the
>> center conductor of the antenna jack. Hook headphones
>> to the handheld radio. Now start the aircraft and use
>> the radio as a test wand and run it around the wiring
>> to try and find the source. This is not easy and takes
>> some effort.
>>> Bottom line: Your noise is coming from your P
>> leads and new tach. Good luck. Merry Christmas.
>>> Mark Bitterlich
>>>
>>>
>>> --- On Fri, 12/17/10, Scott Poehlmann<scott-p@texas.net>
>> wrote:
>>>> From: Scott Poehlmann<scott-p@texas.net>
>>>> Subject: Re: Yak-List: RF interference
>>>> To: yak-list@matronics.com
>>>> Date: Friday, December 17, 2010, 9:03 PM
>>>> --> Yak-List message posted by:
>>>> Scott Poehlmann<scott-p@texas.net>
>>>>
>>>> Thanks Mark,
>>>>
>>>> I knew that you would have a great, step by step
>> method.
>>>> Went out to the hangar today: looks like the
>> P-leads are
>>>> the
>>>> culprit--BOTH have the shielding detached from
>> the
>>>> connector and about 1
>>>> cm of unshielded lead "hanging in the breeze".
>> I'll spend
>>>> some time
>>>> tomorrow AM soldering the shielding to the
>> connector (it
>>>> appears that
>>>> this has been done before and that the solder
>> joints have
>>>> failed...),
>>>> and will advise if this doesn't fix the problem.
>>>>
>>>> Now for the next question: any ideas where to find
>> a cover
>>>> for the tach
>>>> generator drive? I am running a Horizon digital
>> tach (which
>>>> takes its
>>>> data from the mag--in fact it is wired into the
>> back of the
>>>> mag
>>>> switch...), and I have no tach generator, just a
>> big open
>>>> fitting with a
>>>> drive (and seal) at the bottom... Threaded on the
>> outside,
>>>> of course.
>>>>
>>>> Thanks again, and to everyone else who provided
>>>> information. This list
>>>> is a tremendous asset to the continued operation
>> of these
>>>> airplanes.
>>>>
>>>> Scott
>>>>
>>>> On 12-17-2010 10:15, Yak Pilot wrote:
>>>>> --> Yak-List message
>> posted by: Yak
>>>> Pilot<yakplt@yahoo.com>
>>>>> Do the following:
>>>>>
>>>>> Remove the plug from the Tach Gen and tie it
>> back. Run
>>>> the aircraft. Does the noise go away?
>> Then it is
>>>> indeed your Tach Gen and it is most likely
>> shielding at the
>>>> Tach Generator plug itself. Be careful
>> taking this
>>>> plug apart as it is common for the soldering on
>> these wires
>>>> to break.
>>>>> If the noise does not go away, fly the
>> airplane.
>>>> Over the airport come to complete idle and then
>> shut the
>>>> mags off. Both mags, turn them off.
>>>>> You're now a glider.
>>>>>
>>>>> Did the noise go away? If it did, then
>> you have
>>>> a MAG noise problem. The mag noise filters
>> will help,
>>>> but before you go to that effort, look at the P
>> leak plugs
>>>> that go into the side of the mags. It is
>> very common
>>>> for people to twist these plugs off during some
>> kind of
>>>> maint. action and in the process twist the shield
>> right off
>>>> the plug as well. If the P Lead is
>> unshielded you will
>>>> have one huge amount of noise.
>>>>> If the noise is still there even when you
>> have
>>>> performed these steps (whcih is highly unlikely)
>> then you've
>>>> got some other device radiating energy in the
>>>> aircraft. Start turning everything that you
>> can off to
>>>> try and identify it.
>>>>> Suggestions have been made to see if it is
>> coming in
>>>> via the antenna or the power wiring. I have
>> posted
>>>> these suggestions before, but it is something you
>> do at the
>>>> end of troubleshooting and not the
>> beginning. It is
>>>> much easier to identify the noise source and
>> eliminate it
>>>> where it is coming from. If you can't
>> identify the
>>>> noise and you are lucky enough to have it coming
>> in via the
>>>> power wires (again this is rare), a choke on the
>> input power
>>>> wiring can help eliminate the noise. This
>> can be as
>>>> simple as a snap on torroid, or an expensive
>> (purchased)
>>>> filter, that is usually some sort of "Pi L brute
>> force"
>>>> filter consisting of two caps and an inductor.
>>>> Usually, snap on torroids are just as effective
>> and much
>>>> cheaper. Again though, noise coming in via
>> the power
>>>> wiring is rare. It usually is coming in via
>> the
>>>> antenna, and that means you MUST eliminate the
>> noise at it's
>>>> source.
>>>>> The tests described above will usually nail
>> the
>>>> problem in short order.
>>>>> Mark Bitterlich
>>>>>
>>>>> p.s. The reason I recommend shutting the
>> mags
>>>> off at idle in flight versus doing it on the
>> ground is
>>>> because the engine keeps wind-milling even with
>> the mags
>>>> off, and you can leave them off much longer while
>> you are
>>>> listening for radio noise and seeing if it goes
>> away.
>>>> Shutting the engine off with the mags and the
>> engine
>>>> windmilling with it at idle will not hurt
>> anything, although
>>>> the engine will cool off really fast, so when you
>> turn the
>>>> mags back on and the engine once again is
>> actually
>>>> "running", don't just cob the power to 100%.
>> Bring it
>>>> in slowly. Common sense applies.
>>>>> --- On Thu, 12/16/10, Roger Kemp M.D.<viperdoc@mindspring.com>
>>>> wrote:
>>>>>> From: Roger Kemp M.D.<viperdoc@mindspring.com>
>>>>>> Subject: RE: Yak-List: RF interference
>>>>>> To: yak-list@matronics.com
>>>>>> Date: Thursday, December 16, 2010, 1:35
>> PM
>>>>>> --> Yak-List message
>> posted by:
>>>>>> "Roger Kemp M.D."<viperdoc@mindspring.com>
>>>>>>
>>>>>> Check the shielding on your Tac Generator.
>> That is
>>>> the most
>>>>>> likely source
>>>>>> for RPM related noise.
>>>>>> Doc
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: owner-yak-list-server@matronics.com
>>>>>> [mailto:owner-yak-list-server@matronics.com]
>>>>>> On Behalf Of Scott Poehlmann
>>>>>> Sent: Thursday, December 16, 2010 5:07 AM
>>>>>> To: yak-list@matronics.com
>>>>>> Subject: Yak-List: RF interference
>>>>>>
>>>>>> --> Yak-List message
>> posted by: Scott
>>>> Poehlmann<scott-p@texas.net>
>>>>>> Hi All,
>>>>>>
>>>>>> I am aware this has been discussed before,
>> but as
>>>> the
>>>>>> problem now
>>>>>> effects my own airplane, I have am a bit
>> more
>>>> attentive...
>>>>>> I have a Yak 55M with an auto-plug
>> conversion.
>>>> The
>>>>>> conversion has been
>>>>>> in place for about 3 years now (roughly
>> 400
>>>> hours). I am
>>>>>> now getting RF
>>>>>> interference picked up in the Briz radio
>> from the
>>>> mags/plug
>>>>>> wires. At
>>>>>> least I assume that is the source, as it
>> is RPM
>>>> dependent.
>>>>>> It has been
>>>>>> present since installation, but has been
>> gradually
>>>> getting
>>>>>> worse over
>>>>>> the past year or so. I assume that there
>> is a
>>>> shielding
>>>>>> issue either at
>>>>>> the mag connection or along the wires
>> somewhere.
>>>> My
>>>>>> question to you is
>>>>>> where should I start to look at trouble
>> shooting
>>>> this
>>>>>> issue, and how do
>>>>>> I go about fixing it (shy of completely
>> replacing
>>>> the plug
>>>>>> wires, which
>>>>>> I'd prefer not to do... But will do if
>> need
>>>> be...)?
>>>>>> Any thoughts you might have on the matter
>> would
>>>> be
>>>>>> appreciated.
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Scott Poehlmann
>>>>>> Yak 55M N155YK
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Lists This Month --
>>>>>> Some AWESOME FREE Gifts!)
>>>>>> Raiser. Click on
>>>>>> out more about
>>>>>> Gifts provided
>>>>>> www.aeroelectric.com
>>>>>> www.buildersbooks.com
>>>>>> www.homebuilthelp.com
>>>>>>
>>>> -Matt
>>>>>> Dralle, List Admin.
>>>>>> Forum -
>>>>>> FAQ,
>>>>>> - MATRONICS
>> WEB FORUMS -
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>> Lists This Month --
>>>> Some AWESOME FREE Gifts!)
>>>> Raiser. Click on
>>>> out more about
>>>> Gifts provided
>>>> www.aeroelectric.com
>>>> www.buildersbooks.com
>>>> www.homebuilthelp.com
>>>>
>> -Matt
>>>> Dralle, List Admin.
>>>> Forum -
>>>> FAQ,
>>>> - MATRONICS WEB FORUMS -
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>> Lists This Month --
>> Some AWESOME FREE Gifts!)
>> Raiser. Click on
>> out more about
>> Gifts provided
>> www.aeroelectric.com
>> www.buildersbooks.com
>> www.homebuilthelp.com
>> -Matt
>> Dralle, List Admin.
>> Forum -
>> FAQ,
>> - MATRONICS WEB FORUMS -
>>
>>
>>
>>
>
>
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