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pa3arw(at)euronet.nl
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 Posted: Sun May 17, 2009 4:43 am Post subject: Interference of GPS on Becker VHF |
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Guys,
May be some of you on the yak net has some idea how to resolve the following problem. Mark any suggestions??
I own a Avmap IV GPS, great tool but it is getting a nuisance in the 52.
The following happens: when on the ground GPS switched on, VHF on, engine NOT running, no interference on VHF at all!
when on the ground GPS switched on, VHF on, engine running (or in the air for that matter), huge interference on VHF, S5 to 6 noise level, i.e. very difficult comms. When switching over on battery (i.e. pulling the plug out...) the problem is as good as gone.
Has any body had this experience also and what have you done about it? I am thinking on a LPF or a separate DC-DC convertor for the AvMap GPS.
In principle the AvMap swallows any voltage between 10 and 36v. I assume that the 28v generator is not producing a nice DC which causes something to start generating a noise, in my case the GPS but I do not have an explanation for that at all....
Any help is appreciated!
Hans
RA3326K / EHSE
[quote][b]
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dsavarese0812(at)bellsout
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pa3arw(at)euronet.nl
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dsavarese0812(at)bellsout
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| Posted: Sun May 17, 2009 5:37 am Post subject: Interference of GPS on Becker VHF |
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Yes, we installed both filters.
Dennis
[quote] ---
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pa3arw(at)euronet.nl
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| Posted: Sun May 17, 2009 5:47 am Post subject: Interference of GPS on Becker VHF |
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Dennis,
Thanks a lot. I'll order the lot from LoneStar. Hope this solves the problem.
Do you happen to have some pictures of the installation, i.e. is it difficult to install the filter on the magneto?
Since I'm doing this now I'll also install the alternator filter.
Again: thanks a lot!
Hans
Van: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] Namens A. Dennis Savarese
Verzonden: zondag 17 mei 2009 15:26
Aan: yak-list(at)matronics.com
Onderwerp: Re: Interference of GPS on Becker VHF
Yes, we installed both filters.
Dennis
[quote] ---
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dsavarese0812(at)bellsout
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| Posted: Sun May 17, 2009 6:47 am Post subject: Interference of GPS on Becker VHF |
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No pictures available. It's VERY easy to install the filter on the magneto. First, ream out the mounting hole on the tab of the magneto filter. It must fit over the stud on the back side of the engine accessory case round rear cover. De-solder the wire from inside the P-lead probe (the part that screws into the magneto). Crimp a solderless lug on the desoldered wire. Attach the crimp lug to the screw end of the magneto filter. Solder the open end wire back into the P-lead probe. Remove one nut and lock washer from the round accessory case rear cover. Mount the magneto filter to this stud and secure with the nut and lock washer just removed. Do the same for both magnetos.
Dennis
[quote] ---
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viperdoc(at)mindspring.co
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| Posted: Sun May 17, 2009 7:23 am Post subject: Interference of GPS on Becker VHF |
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Two magneto filters are required.
Doc
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese
Sent: Sunday, May 17, 2009 8:26 AM
To: yak-list(at)matronics.com
Subject: Re: Interference of GPS on Becker VHF
Yes, we installed both filters.
Dennis
| Quote: |
----- Original Message -----
From: Hans Oortman (pa3arw(at)euronet.nl)
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Sent: Sunday, May 17, 2009 8:22 AM
Subject: RE: Yak-List: Interference of GPS on Becker VHF
Dennis,
Did you install the in-line filter as well as the magneto filter??
Hans
Van: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com] Namens A. Dennis Savarese
Verzonden: zondag 17 mei 2009 15:03
Aan: yak-list(at)matronics.com (yak-list(at)matronics.com)
Onderwerp: Re: Interference of GPS on Becker VHF
We recently had a problem with Doc's Yak 50 with noise on the Becker VHF. First we installed a nice inline filter on the DC buss; http://www.lonestaraviation.com/product_details.asp?Product_Name=The%20Eliminator. It removed much of the noise, but not all. Then we installed the magneto filters directly on the P leads going into the magnetos. http://www.lonestaraviation.com/product_details.asp?Product_Name=Magneto%20Filter. Bingo.....noise eliminated. I mounted the ground strap to the studs on the accessory case back plate.
Dennis
| Quote: |
----- Original Message -----
From: Hans Oortman (pa3arw(at)euronet.nl)
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Sent: Sunday, May 17, 2009 7:42 AM
Subject: Yak-List: Interference of GPS on Becker VHF
Guys,
May be some of you on the yak net has some idea how to resolve the following problem. Mark any suggestions??
I own a Avmap IV GPS, great tool but it is getting a nuisance in the 52.
The following happens: when on the ground GPS switched on, VHF on, engine NOT running, no interference on VHF at all!
when on the ground GPS switched on, VHF on, engine running (or in the air for that matter), huge interference on VHF, S5 to 6 noise level, i.e. very difficult comms. When switching over on battery (i.e. pulling the plug out...) the problem is as good as gone.
Has any body had this experience also and what have you done about it? I am thinking on a LPF or a separate DC-DC convertor for the AvMap GPS.
In principle the AvMap swallows any voltage between 10 and 36v. I assume that the 28v generator is not producing a nice DC which causes something to start generating a noise, in my case the GPS but I do not have an explanation for that at all....
Any help is appreciated!
Hans
RA3326K / EHSE | Quote: | | href="http://www.matronics.com/Navigator?Yak-List">http://www.matronhref="http://forums.matronics.com">http://forums.matronics.comhref="http://www.matronics.com/contribution">http://www.matronics.com/c |
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[quote][b]
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pa3arw(at)euronet.nl
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| Posted: Sun May 17, 2009 8:27 am Post subject: Interference of GPS on Becker VHF |
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Thanks Dennis...thanks Doc! I'll give it a go.
Hans
Van: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] Namens A. Dennis Savarese
Verzonden: zondag 17 mei 2009 16:43
Aan: yak-list(at)matronics.com
Onderwerp: Re: Interference of GPS on Becker VHF
No pictures available. It's VERY easy to install the filter on the magneto. First, ream out the mounting hole on the tab of the magneto filter. It must fit over the stud on the back side of the engine accessory case round rear cover. De-solder the wire from inside the P-lead probe (the part that screws into the magneto). Crimp a solderless lug on the desoldered wire. Attach the crimp lug to the screw end of the magneto filter. Solder the open end wire back into the P-lead probe. Remove one nut and lock washer from the round accessory case rear cover. Mount the magneto filter to this stud and secure with the nut and lock washer just removed. Do the same for both magnetos.
Dennis
[quote] ---
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pfstelwagon(at)earthlink.
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| Posted: Sun May 17, 2009 10:05 am Post subject: Interference of GPS on Becker VHF |
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Make sure that you have a GOOD ground wire from the engine to the structure.
Frank
N23021
[quote] ---
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yakplt(at)yahoo.com
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| Posted: Sun May 17, 2009 8:51 pm Post subject: Interference of GPS on Becker VHF |
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One of the most common sources of interference to radios is from the P leads. One of the most common causes for that is the loss of a ground for the shield. The way this happens is when you unscrew the P lead connector on the mag itself, you do not also hold the shield cup on the back of the P lead connector still as you unscrew the P lead connector itself. The result of this is that you end up twisting the shield right off the connector.
When you do this, the shield is no longer grounded. If the shield is not grounded, it will radiate noise just like there was no shield there to begin with and your radios will be filled with static and noise.
So, before you go out and install any kind of filters, ALWAYS make sure that your P LEAD shields are indeed correctly soldered and attached to the P lead connector itself.
If everything is ok in that department and you still have noise and decide to try a P lead filter, install it any way you choose, but make certain that when you are done, the P lead shield itself still has a proper ground on it, if not at the P lead connector itself, then in some other manner as you see fit. Do not allow the P lead wire shield "float", and keep the amount of unshielded P lead wire as short as possible when installing a filter and keep the length of the wire from the P lead shield to ground as short as possible as well.
Another terrific source of noise is the Tach Gen, and if the shield on that wire bundle breaks, the noise can be so strong it will burn out the receiver on a Balkan 5.
Mark Bitterlich
From: Roger Kemp M.D. <viperdoc(at)mindspring.com>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 11:10:52 AM
Subject: RE: Interference of GPS on Becker VHF
Two magneto filters are required.
Doc
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese
Sent: Sunday, May 17, 2009 8:26 AM
To: yak-list(at)matronics.com
Subject: Re: Interference of GPS on Becker VHF
Yes, we installed both filters.
Dennis
[quote]
---
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yakplt(at)yahoo.com
Guest
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| Posted: Sun May 17, 2009 9:23 pm Post subject: Interference of GPS on Becker VHF |
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I am not at all sure what the actual details are here.
The fact that you are talking about a GPS and a RADIO makes me think that somehow the problem involves both instruments.
I understand that there is no problem when the engine is not running.
I understand that there is a problem when the engine IS running,
But are you saying that when you unplug the GPS from the aircraft power source and run it on batteries that the noise on the radio goes away?
You mention "pulling the plug out" and then the noise goes away. WHAT PLUG? GPS power plug? Radio power plug? Aircraft external power plug? What?
There are two ways that noise can get into a radio. One is from noise that comes into the antenna itself. This can easily be noise from a MAG P Lead caused by a broken shield, or just a real noisy mag for that matter. Fixing the shield on the P lead, and in some cases adding a MAG P LEAD FILTER, will help radio noise that is caused by this kind of energy getting into the antenna.
The other way noise can get in is via the power wiring to the radio itself. Sometimes the noise from mag P leads can actually put noise into the power wiring as well and again, checking the shielding and maybe installing a filter can help.
BUT!!!!!!!
If you are saying that you have noise on the radio, but when you unplug the power to the GPS, the noise to the radio goes away, then it can be an entirely different problem and have little to do with P leads, or broken shielding, etc.
In many cases, processor noise can ride out a power line on a device, couple to the power buss and be felt on other devices. This can often be cured by using an RF Choke on the power wire itself... such as the GPS power wire, and the power wiring going to the radio. This is normally done by adding a toroidal choke. You can see these installed on most old computer monitor power cables as the large "bulge" in the cable. Radio Shack used to sell them, but I am not sure if they do anymore. Any type 43 ferrite core will work, and you just wrap the power wires through the thing much like you would wrap wires through a donut.
Reading your problem through for the third time, it does sound like to me you really are saying that the problem goes away completely when you unplug the GPS from the aircraft power source with the engine running. If that is indeed the case, it is doubtful that P lead filters or DC bus filters will help. In your case, it is likely that what is causing the problem is the internal battery charger in the GPS unit itself putting a noise back onto the aircraft power bus which is getting into the radios wiring... or worse yet, that the GPS battery charger is RADIATING a noise that is getting into the radios antenna. Easy to tell... unplug the antenna to the radio and see if the noise goes away or gets much less. Also, take a handheld radio and hold it near the GPS with it plugged into the aircraft and the aircraft running. If you hear it loudly in the handheld, remove the handheld antenna and see if it goes away. If it does, it is radiated noise getting into the antenna. If you do not hear the noise in the handheld at all, and you hear it in your aircraft radio with the aircraft antenna unhooked as well, then it is getting into the power wiring and coming in that way. In that case, you need to install a good toroidal choke on the GPS power wiring as close to the GPS unit itself as possible. If THAT does not work, then well... take 2 aspirin get plenty of rest and send me a personal email.
Mark Bitterlich
From: Hans Oortman <pa3arw(at)euronet.nl>
To: yak-list(at)matronics.com
Sent: Sunday, May 17, 2009 8:42:40 AM
Subject: Interference of GPS on Becker VHF
Guys,
May be some of you on the yak net has some idea how to resolve the following problem. Mark any suggestions??
I own a Avmap IV GPS, great tool but it is getting a nuisance in the 52.
The following happens: when on the ground GPS switched on, VHF on, engine NOT running, no interference on VHF at all!
when on the ground GPS switched on, VHF on, engine running (or in the air for that matter), huge interference on VHF, S5 to 6 noise level, i.e. very difficult comms. When switching over on battery (i.e. pulling the plug out...) the problem is as good as gone.
Has any body had this experience also and what have you done about it? I am thinking on a LPF or a separate DC-DC convertor for the AvMap GPS.
In principle the AvMap swallows any voltage between 10 and 36v. I assume that the 28v generator is not producing a nice DC which causes something to start generating a noise, in my case the GPS but I do not have an explanation for that at all....
Any help is appreciated!
Hans
RA3326K / EHSE
[quote][b][b]
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yakplt(at)yahoo.com
Guest
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| Posted: Sun May 17, 2009 9:53 pm Post subject: Interference of GPS on Becker VHF |
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Let me clarify a little here. There is a shielded P lead wire. The center conductor is soldered to a little device that fits into the mag itself and makes an internal connection to the mag coil. You push this into the mag P lead hole and THEN screw on the outer shell per se.
The shield for this wire is soldered to a wire CUP that fits into the screw on portion of the mag P lead connector AKA "The Shell". When you screw in the P lead connector onto the mag, or OFF of the mag, it is very easy to turn the threaded portion and ALSO turn the little piece that is soldered to the shield. If you DO turn this little piece as you screw off the threaded portion of the P lead connector, you will also twist the shield, and in so-doing will cause the shield to rip off from the connector. Thus the shield is no longer connected and there is no ground for it.
It is like MASSIVELY EASY to do this! EVERY SINGLE AIRCRAFT USING AN M-14 ENGINE I HAVE EVER SEEN HAS AT LEAST SOME DAMAGE IN THIS AREA! Every single one. This WILL cause radio noise. Every time. (Hans, your problem is likely something else)
The only way to avoid doing it is to "somehow" carefully hold that cup piece that sticks out the back of the threaded portion of the connector (the NUT per se) still as you turn the piece that screws off with your hand. I have a special tool made to do this. You can use needle nose pliers if you are careful. But if you ignore this advice and take off a P lead connector... you have VERY HIGH ODDS of damaging the shield.
Rest assured, if you didn't know this, it is even money that your P lead shields are at the very minimum "damaged" if not completely broken.
Mark
From: Yak Pilot <yakplt(at)yahoo.com>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 12:47:56 AM
Subject: Re: Interference of GPS on Becker VHF
One of the most common sources of interference to radios is from the P leads. One of the most common causes for that is the loss of a ground for the shield. The way this happens is when you unscrew the P lead connector on the mag itself, you do not also hold the shield cup on the back of the P lead connector still as you unscrew the P lead connector itself. The result of this is that you end up twisting the shield right off the connector.
When you do this, the shield is no longer grounded. If the shield is not grounded, it will radiate noise just like there was no shield there to begin with and your radios will be filled with static and noise.
So, before you go out and install any kind of filters, ALWAYS make sure that your P LEAD shields are indeed correctly soldered and attached to the P lead connector itself.
If everything is ok in that department and you still have noise and decide to try a P lead filter, install it any way you choose, but make certain that when you are done, the P lead shield itself still has a proper ground on it, if not at the P lead connector itself, then in some other manner as you see fit. Do not allow the P lead wire shield "float", and keep the amount of unshielded P lead wire as short as possible when installing a filter and keep the length of the wire from the P lead shield to ground as short as possible as well.
Another terrific source of noise is the Tach Gen, and if the shield on that wire bundle breaks, the noise can be so strong it will burn out the receiver on a Balkan 5.
Mark Bitterlich
From: Roger Kemp M.D. <viperdoc(at)mindspring.com>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 11:10:52 AM
Subject: RE: Interference of GPS on Becker VHF
Two magneto filters are required.
Doc
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese
Sent: Sunday, May 17, 2009 8:26 AM
To: yak-list(at)matronics.com
Subject: Re: Interference of GPS on Becker VHF
Yes, we installed both filters.
Dennis
[quote]
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pa3arw(at)euronet.nl
Guest
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| Posted: Mon May 18, 2009 1:13 am Post subject: Interference of GPS on Becker VHF |
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Mark,
Thanks for all the good advise/suggestions. I’ll have a look at the shieldings. When you mentioned this, I went back in history and tried to recall when this phenoma started to occur. It is only since the last year and a half or so that this has become a real problem.
I don’t fly a lot with gps but when I do, I need it, if you know what I mean.
As far as I can recall it happened after a 100hrs check up (done by our Lithuanian mechanic). At the same time, almost 2 years ago, I used the opportunity to install an additional power connector of the Lemo type. These Swiss connectors are the best you can find and have a lock facility build in rather than the normal cigarette lighter connectors which are big and have as good as no locking facility. I use those Lemo’s in my company for equipment we design/produce for cable companies. To make sure that this power lead does not pick up RF, I installed a RF-choke just before the connector.
When the engine is not running I hear no interference on any channel on the Becker Radio. The GPS is connected to the YAK52’s power and there are no problems what so ever.
It is only after I start the engine that the problem occurs as long as I have the GPS connected to the planes power. When I disconnect the power lead (a long curled cable) from the planes power the problem is gone. The AvMap IV does have a RF choke in its power lead.
I was under the impression that the problem was caused by the gps but it is the combination of the set up, i.e. engine, radio, gps, which causes this problem, not an individual piece of equipment….I think…..and only when the engine is running.
I’ll check the shields of the p-leads on both mags. The tacho generator has already been checked and the shielding of that device is OK.
Installing these filters won’t hurt any way, so I’ll order them, just in case…
Thanks for your help and advise!
Hans Oortman, MBA, Ph.D.
CEO
STN BV
Van: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] Namens Yak Pilot
Verzonden: maandag 18 mei 2009 7:53
Aan: yak-list(at)matronics.com
Onderwerp: Re: Yak-List: Interference of GPS on Becker VHF
Let me clarify a little here. There is a shielded P lead wire. The center conductor is soldered to a little device that fits into the mag itself and makes an internal connection to the mag coil. You push this into the mag P lead hole and THEN screw on the outer shell per se.
The shield for this wire is soldered to a wire CUP that fits into the screw on portion of the mag P lead connector AKA "The Shell". When you screw in the P lead connector onto the mag, or OFF of the mag, it is very easy to turn the threaded portion and ALSO turn the little piece that is soldered to the shield. If you DO turn this little piece as you screw off the threaded portion of the P lead connector, you will also twist the shield, and in so-doing will cause the shield to rip off from the connector. Thus the shield is no longer connected and there is no ground for it.
It is like MASSIVELY EASY to do this! EVERY SINGLE AIRCRAFT USING AN M-14 ENGINE I HAVE EVER SEEN HAS AT LEAST SOME DAMAGE IN THIS AREA! Every single one. This WILL cause radio noise. Every time. (Hans, your problem is likely something else)
The only way to avoid doing it is to "somehow" carefully hold that cup piece that sticks out the back of the threaded portion of the connector (the NUT per se) still as you turn the piece that screws off with your hand. I have a special tool made to do this. You can use needle nose pliers if you are careful. But if you ignore this advice and take off a P lead connector... you have VERY HIGH ODDS of damaging the shield.
Rest assured, if you didn't know this, it is even money that your P lead shields are at the very minimum "damaged" if not completely broken.
Mark
From: Yak Pilot <yakplt(at)yahoo.com>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 12:47:56 AM
Subject: Re: Yak-List: Interference of GPS on Becker VHF
One of the most common sources of interference to radios is from the P leads. One of the most common causes for that is the loss of a ground for the shield. The way this happens is when you unscrew the P lead connector on the mag itself, you do not also hold the shield cup on the back of the P lead connector still as you unscrew the P lead connector itself. The result of this is that you end up twisting the shield right off the connector.
When you do this, the shield is no longer grounded. If the shield is not grounded, it will radiate noise just like there was no shield there to begin with and your radios will be filled with static and noise.
So, before you go out and install any kind of filters, ALWAYS make sure that your P LEAD shields are indeed correctly soldered and attached to the P lead connector itself.
If everything is ok in that department and you still have noise and decide to try a P lead filter, install it any way you choose, but make certain that when you are done, the P lead shield itself still has a proper ground on it, if not at the P lead connector itself, then in some other manner as you see fit. Do not allow the P lead wire shield "float", and keep the amount of unshielded P lead wire as short as possible when installing a filter and keep the length of the wire from the P lead shield to ground as short as possible as well.
Another terrific source of noise is the Tach Gen, and if the shield on that wire bundle breaks, the noise can be so strong it will burn out the receiver on a Balkan 5.
Mark Bitterlich
From: Roger Kemp M.D. <viperdoc(at)mindspring.com>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 11:10:52 AM
Subject: RE: Yak-List: Interference of GPS on Becker VHF
Two magneto filters are required.
Doc
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese
Sent: Sunday, May 17, 2009 8:26 AM
To: yak-list(at)matronics.com
Subject: Re: Yak-List: Interference of GPS on Becker VHF
Yes, we installed both filters.
Dennis
[quote]
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dsavarese0812(at)bellsout
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| Posted: Mon May 18, 2009 3:53 am Post subject: Interference of GPS on Becker VHF |
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I failed to mention in my installation description that the wire end of the filter is a shielded wire and the shield should be soldered to the cup on the P lead end where the old braided shield was soldered to.
Dennis
[quote] ---
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yakplt(at)yahoo.com
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| Posted: Wed May 20, 2009 7:45 pm Post subject: Interference of GPS on Becker VHF |
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Hans, this is a much better explanation. Try this. Next time you go fly, leave the power lead connected for the GPS, but if possible unplug the GPS itself while leaving the power cord connected to the aircraft. Hopefully there is a disconnect plug at the GPS itself that would allow you to keep the GPS power cord connected with the actual GPS removed. Also tell me what happens if you TURN THE GPS OFF in flight! Does this impact the noise in the radio with the engine running? If NOT, then for some reason your GPS power cable is either radiating noise "somehow" or is picking noise up and putting it back into wiring where it should not be.
While unusual, this kind of thing is not unknown.
I suggest replacing your GPS power wire with dual conductor SHIELDED wire and make sure the shield is connected to ground at the power connector side only.
Also, reducing RF noise from the Mags by using filters is never a bad idea. Before you do that, PLEASE check the P lead shields right at the MAG P LEAD CONNECTOR and make sure they are not twisted off! That happens ALL the time, and you need to physically check this yourself. When you unscrew the P lead connector on the mag, be SURE to hold the center of it still as you rotate the knurled knob or you will twist the shield right off.
Best Regards,
Mark Bitterlich
From: Hans Oortman <pa3arw(at)euronet.nl>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 5:12:12 AM
Subject: RE: Interference of GPS on Becker VHF
Mark,
Thanks for all the good advise/suggestions. I’ll have a look at the shieldings. When you mentioned this, I went back in history and tried to recall when this phenoma started to occur. It is only since the last year and a half or so that this has become a real problem.
I don’t fly a lot with gps but when I do, I need it, if you know what I mean.
As far as I can recall it happened after a 100hrs check up (done by our Lithuanian mechanic). At the same time, almost 2 years ago, I used the opportunity to install an additional power connector of the Lemo type. These Swiss connectors are the best you can find and have a lock facility build in rather than the normal cigarette lighter connectors which are big and have as good as no locking facility. I use those Lemo’s in my company for equipment we design/produce for cable companies. To make sure that this power lead does not pick up RF, I installed a RF-choke just before the connector.
When the engine is not running I hear no interference on any channel on the Becker Radio. The GPS is connected to the YAK52’s power and there are no problems what so ever.
It is only after I start the engine that the problem occurs as long as I have the GPS connected to the planes power. When I disconnect the power lead (a long curled cable) from the planes power the problem is gone. The AvMap IV does have a RF choke in its power lead.
I was under the impression that the problem was caused by the gps but it is the combination of the set up, i.e. engine, radio, gps, which causes this problem, not an individual piece of equipment….I think…..and only when the engine is running.
I’ll check the shields of the p-leads on both mags. The tacho generator has already been checked and the shielding of that device is OK.
Installing these filters won’t hurt any way, so I’ll order them, just in case…
Thanks for your help and advise!
Hans Oortman, MBA, Ph.D.
CEO
STN BV
Van: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] Namens Yak Pilot
Verzonden: maandag 18 mei 2009 7:53
Aan: yak-list(at)matronics.com
Onderwerp: Re: Interference of GPS on Becker VHF
Let me clarify a little here. There is a shielded P lead wire. The center conductor is soldered to a little device that fits into the mag itself and makes an internal connection to the mag coil. You push this into the mag P lead hole and THEN screw on the outer shell per se.
The shield for this wire is soldered to a wire CUP that fits into the screw on portion of the mag P lead connector AKA "The Shell". When you screw in the P lead connector onto the mag, or OFF of the mag, it is very easy to turn the threaded portion and ALSO turn the little piece that is soldered to the shield. If you DO turn this little piece as you screw off the threaded portion of the P lead connector, you will also twist the shield, and in so-doing will cause the shield to rip off from the connector. Thus the shield is no longer connected and there is no ground for it.
It is like MASSIVELY EASY to do this! EVERY SINGLE AIRCRAFT USING AN M-14 ENGINE I HAVE EVER SEEN HAS AT LEAST SOME DAMAGE IN THIS AREA! Every single one. This WILL cause radio noise. Every time. (Hans, your problem is likely something else)
The only way to avoid doing it is to "somehow" carefully hold that cup piece that sticks out the back of the threaded portion of the connector (the NUT per se) still as you turn the piece that screws off with your hand. I have a special tool made to do this. You can use needle nose pliers if you are careful. But if you ignore this advice and take off a P lead connector... you have VERY HIGH ODDS of damaging the shield.
Rest assured, if you didn't know this, it is even money that your P lead shields are at the very minimum "damaged" if not completely broken.
Mark
From: Yak Pilot <yakplt(at)yahoo.com>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 12:47:56 AM
Subject: Re: Interference of GPS on Becker VHF
One of the most common sources of interference to radios is from the P leads. One of the most common causes for that is the loss of a ground for the shield. The way this happens is when you unscrew the P lead connector on the mag itself, you do not also hold the shield cup on the back of the P lead connector still as you unscrew the P lead connector itself. The result of this is that you end up twisting the shield right off the connector.
When you do this, the shield is no longer grounded. If the shield is not grounded, it will radiate noise just like there was no shield there to begin with and your radios will be filled with static and noise.
So, before you go out and install any kind of filters, ALWAYS make sure that your P LEAD shields are indeed correctly soldered and attached to the P lead connector itself.
If everything is ok in that department and you still have noise and decide to try a P lead filter, install it any way you choose, but make certain that when you are done, the P lead shield itself still has a proper ground on it, if not at the P lead connector itself, then in some other manner as you see fit. Do not allow the P lead wire shield "float", and keep the amount of unshielded P lead wire as short as possible when installing a filter and keep the length of the wire from the P lead shield to ground as short as possible as well.
Another terrific source of noise is the Tach Gen, and if the shield on that wire bundle breaks, the noise can be so strong it will burn out the receiver on a Balkan 5.
Mark Bitterlich
From: Roger Kemp M.D. <viperdoc(at)mindspring.com>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 11:10:52 AM
Subject: RE: Interference of GPS on Becker VHF
Two magneto filters are required.
Doc
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese
Sent: Sunday, May 17, 2009 8:26 AM
To: yak-list(at)matronics.com
Subject: Re: Interference of GPS on Becker VHF
Yes, we installed both filters.
Dennis
[quote]
---
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http://www.matronics.com/Navigator?Yak-List |
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pa3arw(at)euronet.nl
Guest
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| Posted: Wed May 20, 2009 11:46 pm Post subject: Interference of GPS on Becker VHF |
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Mark,
Thanks for the suggestions. I am going to do those in the next few days. We have a few bank holidays any way so, time to fly.
I ordered the filters, just in case, it certainly won't hurt to install these and at the same time I can check the shielding at the P-lead.
I'll keep you updated!
Hans
Tel: +31 653 286022
Van: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] Namens Yak Pilot
Verzonden: donderdag 21 mei 2009 5:37
Aan: yak-list(at)matronics.com
Onderwerp: Re: Interference of GPS on Becker VHF
Hans, this is a much better explanation. Try this. Next time you go fly, leave the power lead connected for the GPS, but if possible unplug the GPS itself while leaving the power cord connected to the aircraft. Hopefully there is a disconnect plug at the GPS itself that would allow you to keep the GPS power cord connected with the actual GPS removed. Also tell me what happens if you TURN THE GPS OFF in flight! Does this impact the noise in the radio with the engine running? If NOT, then for some reason your GPS power cable is either radiating noise "somehow" or is picking noise up and putting it back into wiring where it should not be.
While unusual, this kind of thing is not unknown.
I suggest replacing your GPS power wire with dual conductor SHIELDED wire and make sure the shield is connected to ground at the power connector side only.
Also, reducing RF noise from the Mags by using filters is never a bad idea. Before you do that, PLEASE check the P lead shields right at the MAG P LEAD CONNECTOR and make sure they are not twisted off! That happens ALL the time, and you need to physically check this yourself. When you unscrew the P lead connector on the mag, be SURE to hold the center of it still as you rotate the knurled knob or you will twist the shield right off.
Best Regards,
Mark Bitterlich
From: Hans Oortman <pa3arw(at)euronet.nl>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 5:12:12 AM
Subject: RE: Interference of GPS on Becker VHF
UNKNOWN { FONT-FAMILY: "Cambria Math"; panose-1: 2 4 5 3 5 4 6 3 2 4 } UNKNOWN { FONT-FAMILY: Calibri; panose-1: 2 15 5 2 2 2 4 3 2 4 } UNKNOWN { FONT-FAMILY: Tahoma; panose-1: 2 11 6 4 3 5 4 4 2 4 } UNKNOWN { FONT-FAMILY: Consolas; panose-1: 2 11 6 9 2 2 4 3 2 4 } UNKNOWN { MARGIN: 1in } UNKNOWN { FONT-FAMILY: Tahoma; panose-1: 2 11 6 4 3 5 4 4 2 4 } UNKNOWN { FONT-FAMILY: Consolas; panose-1: 2 11 6 9 2 2 4 3 2 4 } UNKNOWN { FONT-FAMILY: Calibri; panose-1: 2 15 5 2 2 2 4 3 2 4 } UNKNOWN { FONT-FAMILY: cou; panose-1: 0 0 0 0 0 0 0 0 0 0 } UNKNOWN { panose-1: 0 0 0 0 0 0 0 0 0 0 } P.MsoNormal { MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Times New Roman"; FONT-SIZE: 12pt } LI.MsoNormal { MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Times New Roman"; FONT-SIZE: 12pt } DIV.MsoNormal { MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Times New Roman"; FONT-SIZE: 12pt } A:link { COLOR: blue; TEXT-DECORATION: underline } SPAN.MsoHyperlink { COLOR: blue; TEXT-DECORATION: underline } A:visited { COLOR: purple; TEXT-DECORATION: underline } SPAN.MsoHyperlinkFollowed { COLOR: purple; TEXT-DECORATION: underline } PRE { MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Courier New"; FONT-SIZE: 10pt } P.msochpdefault { FONT-FAMILY: "Times New Roman"; MARGIN-LEFT: 0cm; FONT-SIZE: 10pt; MARGIN-RIGHT: 0cm } LI.msochpdefault { FONT-FAMILY: "Times New Roman"; MARGIN-LEFT: 0cm; FONT-SIZE: 10pt; MARGIN-RIGHT: 0cm } DIV.msochpdefault { FONT-FAMILY: "Times New Roman"; MARGIN-LEFT: 0cm; FONT-SIZE: 10pt; MARGIN-RIGHT: 0cm } SPAN.htmlpreformattedchar { FONT-FAMILY: Consolas } SPAN.emailstyle19 { FONT-FAMILY: Calibri; COLOR: #1f497d } SPAN.E-mailStijl21 { FONT-FAMILY: Arial; COLOR: navy } UNKNOWN { MARGIN: 70.85pt } DIV.Section1 { }
Mark,
Thanks for all the good advise/suggestions. I’ll have a look at the shieldings. When you mentioned this, I went back in history and tried to recall when this phenoma started to occur. It is only since the last year and a half or so that this has become a real problem.
I don’t fly a lot with gps but when I do, I need it, if you know what I mean.
As far as I can recall it happened after a 100hrs check up (done by our Lithuanian mechanic). At the same time, almost 2 years ago, I used the opportunity to install an additional power connector of the Lemo type. These Swiss connectors are the best you can find and have a lock facility build in rather than the normal cigarette lighter connectors which are big and have as good as no locking facility. I use those Lemo’s in my company for equipment we design/produce for cable companies. To make sure that this power lead does not pick up RF, I installed a RF-choke just before the connector.
When the engine is not running I hear no interference on any channel on the Becker Radio. The GPS is connected to the YAK52’s power and there are no problems what so ever.
It is only after I start the engine that the problem occurs as long as I have the GPS connected to the planes power. When I disconnect the power lead (a long curled cable) from the planes power the problem is gone. The AvMap IV does have a RF choke in its power lead.
I was under the impression that the problem was caused by the gps but it is the combination of the set up, i.e. engine, radio, gps, which causes this problem, not an individual piece of equipment….I think…..and only when the engine is running.
I’ll check the shields of the p-leads on both mags. The tacho generator has already been checked and the shielding of that device is OK.
Installing these filters won’t hurt any way, so I’ll order them, just in case…
Thanks for your help and advise!
Hans Oortman, MBA, Ph.D.
CEO
STN BV
Van: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] Namens Yak Pilot
Verzonden: maandag 18 mei 2009 7:53
Aan: yak-list(at)matronics.com
Onderwerp: Re: Interference of GPS on Becker VHF
Let me clarify a little here. There is a shielded P lead wire. The center conductor is soldered to a little device that fits into the mag itself and makes an internal connection to the mag coil. You push this into the mag P lead hole and THEN screw on the outer shell per se.
The shield for this wire is soldered to a wire CUP that fits into the screw on portion of the mag P lead connector AKA "The Shell". When you screw in the P lead connector onto the mag, or OFF of the mag, it is very easy to turn the threaded portion and ALSO turn the little piece that is soldered to the shield. If you DO turn this little piece as you screw off the threaded portion of the P lead connector, you will also twist the shield, and in so-doing will cause the shield to rip off from the connector. Thus the shield is no longer connected and there is no ground for it.
It is like MASSIVELY EASY to do this! EVERY SINGLE AIRCRAFT USING AN M-14 ENGINE I HAVE EVER SEEN HAS AT LEAST SOME DAMAGE IN THIS AREA! Every single one. This WILL cause radio noise. Every time. (Hans, your problem is likely something else)
The only way to avoid doing it is to "somehow" carefully hold that cup piece that sticks out the back of the threaded portion of the connector (the NUT per se) still as you turn the piece that screws off with your hand. I have a special tool made to do this. You can use needle nose pliers if you are careful. But if you ignore this advice and take off a P lead connector... you have VERY HIGH ODDS of damaging the shield.
Rest assured, if you didn't know this, it is even money that your P lead shields are at the very minimum "damaged" if not completely broken.
Mark
From: Yak Pilot <yakplt(at)yahoo.com>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 12:47:56 AM
Subject: Re: Interference of GPS on Becker VHF
One of the most common sources of interference to radios is from the P leads. One of the most common causes for that is the loss of a ground for the shield. The way this happens is when you unscrew the P lead connector on the mag itself, you do not also hold the shield cup on the back of the P lead connector still as you unscrew the P lead connector itself. The result of this is that you end up twisting the shield right off the connector.
When you do this, the shield is no longer grounded. If the shield is not grounded, it will radiate noise just like there was no shield there to begin with and your radios will be filled with static and noise.
So, before you go out and install any kind of filters, ALWAYS make sure that your P LEAD shields are indeed correctly soldered and attached to the P lead connector itself.
If everything is ok in that department and you still have noise and decide to try a P lead filter, install it any way you choose, but make certain that when you are done, the P lead shield itself still has a proper ground on it, if not at the P lead connector itself, then in some other manner as you see fit. Do not allow the P lead wire shield "float", and keep the amount of unshielded P lead wire as short as possible when installing a filter and keep the length of the wire from the P lead shield to ground as short as possible as well.
Another terrific source of noise is the Tach Gen, and if the shield on that wire bundle breaks, the noise can be so strong it will burn out the receiver on a Balkan 5.
Mark Bitterlich
From: Roger Kemp M.D. <viperdoc(at)mindspring.com>
To: yak-list(at)matronics.com
Sent: Monday, May 18, 2009 11:10:52 AM
Subject: RE: Yak-List: Interference of GPS on Becker VHF
Two magneto filters are required.
Doc
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese
Sent: Sunday, May 17, 2009 8:26 AM
To: yak-list(at)matronics.com
Subject: Re: Interference of GPS on Becker VHF
Yes, we installed both filters.
Dennis
[quote]
---
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mark.bitterlich(at)navy.m
Guest
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| Posted: Fri May 22, 2009 8:17 am Post subject: Interference of GPS on Becker VHF |
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I am not sure whether I told you this or not Hans, so I might be repeating myself. If you put in the filters, make sure you GROUND the SHIELD on the original P lead wire that will then connect to the new filter.
Mark
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