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ADS-B Out and RF Coupling -- Static

Hiyas Steve with Garmin! Thanks for the reply.

It does not, however, stop an ANR headset from picking up noise if it is prone to do that.

So are you saying that anyone with a Bose A20 ANR headset walking around the perimeter of their aircraft on battery power will pick up this noise? Has this been your experience?

When I installed the GMA 245 into the GMA 240/340 rack, I did not change out the connector backshells to the new style as that was not necessary to eliminate the issue. With proper cable shielding and termination, the new metal backshells do not significantly change the installation.

This is a quote from the instruction manual page A-1...

"If replacing a GMA 240 with a GMA 245, the GMA 240 (330-00220-25) connector backshells can be reused. However, grounding the wire shields to the GMA will be easier with the Garmin backshells in GPN 011-02302-00. The Garmin backshells also offer higher immunity to HIRF. Current installations will not be required to change the backshell type, but would benefit from doing so."

If the benefit in higher immunity to HIRF was good enough, wouldn't this be a preferable choice? This is why I ask if this has been tried.

Reading it a few times more... is current installations referring to a non-Garmin install? So perhaps both backshells offer the same degree of immunity? Please clarify.

Best Regards,
 
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Just curious...How do you guys with carbon airplanes make a good connection to the carbon with the antenna base and/or coax braid?

Bob, here's the transponder antenna installation instructions for the Lancair...Chapter 24

I've been trying to help Chuck with his graphite plane in an effort to eliminate the "victim " path... He has done an outstanding job of shielding with proper grounding and shooting down every other suggestion I could come up with...
So what I think both you lads are suggesting, and which I've had doubts about also is that a proper ground plane and antenna installation needs closer inspection.

If I am not mistaken... you are asking about bonding to composites. You don't. You can imbed conductive material, or you can create a ground plane with metal. Then, a strap or other conductive path leads from the base of the antenna to the conductive material. If it does not conduct, it will not act as a counterpoise to any antenna. Did that just muddy the waters?

...with the base of the antenna connected to the coax shield, with the other end grounded at the transponder, and properly returned to the aircraft avionics grounding buss. This results in a balanced coax output, low VSWR, eliminating "backfeed" and possible HIRF. Also giving the transmitted output gain or direction...keeping it heading down and out but not up.

Shooting the output into a dummy load and eliminating the noise. Doesn't this just leave these issues left?

Would you say this about right? Let's muddy away!:D

If we could only get Andy a 1090 mhz signal generator...:rolleyes:
 
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Another anecdote to add to the collection. I have a GMA 240 audio panel, and after installing the Stratus ESG transponder this past weekend, i went for a flight and immediately upon takeoff noticed the annoying "phbbtt" of the broadcast every few seconds. My first reaction was to recall this thread, followed up by fear that it would be a lifelong issue. Oddly, at some point during the course of the hour-long flight, it stopped. I really don't recall when, only that on the way back it occurred to me that the noise was gone. I looked at the transponder and it was still indicating that signals were being sent and received, but the noise was gone.
Several days later, I flew again. As usual, takeoff is accompanied by some electrical noise which goes away when throttled back. I may have heard a couple of blips from the transponder, but it quickly went away.

Makes me wonder: does the GMA 240 have the ability to "Learn" and filter out undesirable noises, or is this just a fluke that I should count myself lucky to experience?

Headset is a QT Halo in-ear passive unit. Have flown the plane with Active headsets, but not with the ads-b transponder.
 
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Thanks for the manual. But it left me more puzzled. I do not see how the base of the antenna is electrically connected to the outer carbon fiber skin. I see a layer of micro insulating it. And aren't these fibers imbedded in epoxy? How does one assure electrical contact?
 
Another anecdote to add to the collection. I have a GMA 240 audio panel, and after installing the Stratus ESG transponder this past weekend, i went for a flight and immediately upon takeoff noticed the annoying "phbbtt" of the broadcast every few seconds. My first reaction was to recall this thread, followed up by fear that it would be a lifelong issue. Oddly, at some point during the course of the hour-long flight, it stopped. I really don't recall when, only that on the way back it occurred to me that the noise was gone. I looked at the transponder and it was still indicating that signals were being sent and received, but the noise was gone.
Several days later, I flew again. As usual, takeoff is accompanied by some electrical noise which goes away when throttled back. I may have heard a couple of blips from the transponder, but it quickly went away.

Makes me wonder: does the GMA 240 have the ability to "Learn" and filter out undesirable noises, or is this just a fluke that I should count myself lucky to experience?

Headset is a QT Halo in-ear passive unit. Have flown the plane with Active headsets, but not with the ads-b transponder.

I've had this happen with a Mode-C transponder in the plane, but only when I am quite close to the radar station. Same headset.
 
To compliment Bob's comment in post 55, I did a quick test and provide the following VSWR plots of a blade type Transponder antenna.

The first photo shows the VSWR with the antenna mounting studs making good electrical contact with the ground plane. 1.06 at 1029.1 MHz and 1.10 at 1087.2 MHz. Both well within the spec?s listed by the Transponder MFG?s

The second photo shows the VSWR with the antenna mounting studs not in contact with the ground plane. 4.88 at 1029.1 MHz and 4.25 at 1087.2 MHz. Both outside the spec?s listed by the Transponder MFG?s.

6id284.jpg

swzame.jpg
 
That is sure neat Don!
What did you use as a test ground plane? Do you consider graphite the equivalent of aluminum, ground plane wise?
 
I used a 24? x 24? Aluminum sheet for the test in photo 1.

I have not tested Graphite as a ground plane but this study titled ?Effect of Carbon Fiber Composites as Ground Plane Material on Antenna Performance? linked here: https://publik.tuwien.ac.at/files/PubDat_230745.pdf shows little difference to Aluminum.

With that said, it is very important that the antenna mounting studs make good electrical contact with the ground plane for optimum performance.
 
Thanks for the manual. But it left me more puzzled. I do not see how the base of the antenna is electrically connected to the outer carbon fiber skin. I see a layer of micro insulating it. And aren't these fibers imbedded in epoxy? How does one assure electrical contact?

I was thinking along the very same lines Bob. I asked the builder what this material was and posted this picture to him, hoping that the material would make a good ground plane.

Cx4CDrA.jpg


I think 4 bid stands for four layers of bi-directional fibers...no reply back as of today.

Path as far as I can tell is... Antenna base counter sunk bevels, cad coated screws, nut plates, rivets into graphite fibers.:(

I used a 24? x 24? Aluminum sheet for the test in photo 1.

I have not tested Graphite as a ground plane but this study titled ?Effect of Carbon Fiber Composites as Ground Plane Material on Antenna Performance? linked here: https://publik.tuwien.ac.at/files/PubDat_230745.pdf shows little difference to Aluminum.

With that said, it is very important that the antenna mounting studs make good electrical contact with the ground plane for optimum performance.
Well done Don. Great paper. Although I have to say I've read that graphite is not recommended to be used as an antenna ground plane...

May I ask what power output you are using? If your testing above a concrete floor. And lastly, do you have any snap on mix 61 toroidal ferrite cores to attach to the coax cable close to the antenna connection, and retest the bad ground plane example?:eek:
 
I think 4 bid stands for four layers of bi-directional fibers...
Yes. That's exactly correct. I think Burt Rutan was the first to use the "bid" shorthand for "bi-directional", meaning the glass fibers are oriented at +/- 45 degrees to the joint you are reinforcing. Doing it that way has two benefits over orienting the glass fibers at +/- 90 degrees. First, the cloth can better conform to rounded or uneven surfaces. Secondly, it makes the joint stronger because there are twice as many glass fibers crossing the joint as there would be if the fibers were oriented at +/- 90 to the joint. At 45 degrees, each fiber has only 0.707 (square root of two) of the tensile strength, but there are twice as many fibers so the overall strength is 1.414 times as much. Does this make sense?

P.S. You'll want to use crowfoot weave in this example because it's more flexible.
 
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Another anecdote to add to the collection.

Makes me wonder: does the GMA 240 have the ability to "Learn" and filter out undesirable noises, or is this just a fluke that I should count myself lucky to experience?

Ahhhh the more the merrier!:D

Hiyas j-red! Thinking back would you say the problem occurred whilst on or near the ground?
I don't know about the GMA-240 but the Stratus ESG manual mentions that it will automatically switch from ground mode to altitude mode. Doesn't say how, but I imagine it looks at your altitude encoder info and uses that.

From the installation manual...

Ground mode... Key- (none)
Stratus ESG is powered on and in ALT or On mode, but does not report altitude. Ground mode is automatically detected. Press the ALT or ON key to override Ground mode. Press SBY to remove this override.

When your on the ground I would be curious if toggling this on and off would make a difference? Would just adding the requirement to report altitude be enough of a difference...hummmmm.:rolleyes:

Oh and by the by... Are you one that had to coil up a long length of GPS antenna coax cable in the avionics bay to meet minimum dB requirements?:mad:



Hey Snopercod! Good information. Thank you. Does your expertise extend into graphite and composite ground plane installations!:)

Best regards all,
 
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The requirement to automatically switch between air and ground mode is a TSO requirement.
I think most boxes look at GPS ground speed and/or indicated airspeed to make the switch.
 
Does your expertise extend into graphite and composite ground plane installations!:)
No, sorry. I've done a lot of traditional fiberglass work but very little carbon fiber and I don't know nuttin' about CFC ground planes. I did find this, though: Effect of Carbon-Fiber Composites as Ground Plane Material on Antenna Performance. The bottom line is that the CFC ground plane is a little more lossy than aluminum. I'm not understanding why you are even considering that on an aluminum airplane.
 
Thread SUMMARY.

I'm not understanding why you are even considering that on an aluminum airplane.

Long answer to a short question...:D

Yep this thread is getting a bit long in the tooth... let's see if I can summarize.

We are attempting to find the cause and elimination of squitter noise(1090ES transponders ADS-B)that sounds like a tick (also described as a phbbtt) which is not effected by volume controls that is heard in the headsets (passive and active type) of three entirely different types and builds of aircraft listed below.

1) Andy's pusher fiberglass composite Velocity. Original poster.
2) Jeff's RV-7 see post # 3 and 26.
3) Chuck's tractor graphite composite Lancair Legacy. Equipped with retractable gear. see post #44.

Common links are: 1090 ES Transponders, audio panels(most notably the GMA 240, but not exclusively) , and Automatic Noise Reduction and passive headsets.

Known fixes are:

Distance! Move the antenna as far away as possible from the audio equipment. (impossible ins Andy's situation)
Installation of a Garmin 245 audio panel cures the issue for passive headset mode type only.
Note: Installation of a dummy load for testing eliminated the problem.

What's agreed on:

The "SOURCE" are the Transponders...specifically the transmission of the unit reply and ADS-B packets (also know as squitter) that happens about once a second.
The "PATH" of noise is Radio-Frequency Interference (EMI).
And the "VICTIMS" are the audio panels/headsets.

It's apparent that the ANR circuits in "active" headsets are susceptible. Which I gladly leave to the manufactures to correct...

Tried fixes are too numerous to list...you'll have to read for yourself...

But I think it would be safe to say that most efforts have been to harden the audio panels susceptibility to it, coax cables, and attempts at blocking the RFI.


Which brings me to my current working theory.:rolleyes:

I think the problem could be solved by a correct ground plane installation or an antenna modification. Remember, three feet required straight line between transponder and antenna. Extra grounding precautions are also required for transponder cases in composite aircraft.
(Now I KNOW Andy would be the first to say he has tried several ground planes and antennas! As I know he has! But I think we just haven't hit the right combination yet...);)

Why work on a composite first? Because I always like to work on the seemingly harder problem first!

None have done a VSWR test yet which would put some of this to rest quickly.
It also seems that the manufactures are aware of the problem, and working on solutions, so this may be mute with newer equipment installations.




So if all of you would be kind enough to point out my mistakes or additions to this post in a P.M.to me, I'll be happy to update this "summary" as required to keep the posts down... Thanks.

And by all means...Post the correct fix!

With best regards to all,
 
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T.C.,

Sorry for the late reply. As you noted, I am pretty tired when it comes to this. I've tried so many things.

To answer your questions: No, I have not been able to do the VSWR test. I don't have the proper meter and I don't know anyone that has one. If I ever could get the meter I would be happy to try it.

What is different between my airplane and others that don't have the issue? They are all unique aircraft with the builder doing the installation. The hard part is finding out what things matter. Most transponder antennas look very similar to mine. When talking with the engineers, they tell me the shape of the ground plane can affect the performance of the broadcast, but probably not going to change the static.

FWIW, other builders have installed the antennas right under the pilot's seat, in the nose, at the end of the strake, and where I have mine; between the main gear. My understanding is they may have gotten lucky, or maybe call me unlucky (glass half full...) with the position of the antenna relative to their headsets.

People with the problem have both Garmin and Trig transponders. Both Garmin and Lightspeed headsets. People also have the same equipment and are not experiencing the problem.

I don't have the heart or ambition to go on a new transponder location hunt. Not at this time.

Andy
 
Composite Pusher Aircraft...

Hi Andy,

An important question I have is... did you do all testing after making changes in the air? It's become apparent that the transponders output can be reflected off the concrete apron and up into cockpit areas! Especially with a fiberglass airframe. That being said... :rolleyes:

Been working hard to find a solution to your problem of RF interference on your ANR headset.
Two tacts seem possible with keeping your existing headset, and antenna location... Find a way to get RFI OUT of your aircraft...and KEEP it out!
The get it out part would be to go over the transponder, coax, and antenna with ground plane installations once again to make it the best it can be, and/or make modifications to the element's radiation pattern by inducing passive gain with parasitic elements (whew):eek: .....sounds like you'd pass on that at this time.

Or...Keep it out!:)

Here's what I have for your consideration.

RFI Barrier.

Gone off my rocker?;) Perhaps, but think about this... An easy to install (in comparison to aluminum foil sheets),cheap, and light weight (3 oz.). And big enough to cover most of the bottom of your fuselage. Did I mention cheap? This would help to see if more effort in this direction would be worth it.
Think of your transponder antenna as a 100 watt light bulb with your fiberglass fuselage as, well glass. Your goal is to keep the light from reaching your headset, and from bouncing around inside the fuselage (it's already bouncing off your gear...).
But your thinking, I tried all that aluminum wrapping earlier! But you did get some positive results! And this was after the RFI was already in the cockpit. Much like holding an umbrella overhead to block out the sun, and being disappointed it wasn't totally dark. The only real possibility would be to have put your headset in a seamless grounded metal box. But I digress...

Feel like giving it a go? If so, only one side of the Mylar blanket is aluminum coated. you'll have to verify which. I've read where it's resistance is less than 7 ohms corner to corner. That side will face down. You can make no holes in it. And the conductive face must be grounded. By all means go over the top of the antenna and coax.

If you find that this does make a difference... More permanent possibilities are as follows...

The "Good Stuff"
Conductive Paint.
Barrier Materials

Some other thoughts to your most recent post...



T.C.,

What is different between my airplane and others that don't have the issue? They are all unique aircraft with the builder doing the installation. The hard part is finding out what things matter.

When talking with the engineers, they tell me the shape of the ground plane can affect the performance of the broadcast, but probably not going to change the static.

People also have the same equipment and are not experiencing the problem.

Andy

Statement 1: Ah, the lack of commonality. What matters is the efficient discharge of the transponders output. The location of the transponder, audio components, coax cable, and antenna. Their position to each other, and to other wiring. Correct grounding of the transponder, antenna ground plane and audio equipment. The antenna's ground plane size, shape, material, and installation. Just look back on some of the great questions and possible solutions in this thread to see what matters.

Statement 2: A couple points I would like to make is that a poor ground plane could cause back feed on the coax shielding. Causing RF radiation from the coax cable itself which would be closer to the headset location. This results in a bad VSWR test. As per Don..."A bad VSWR can be caused by a number of things, poor antenna grounding, damaged coax or connector, antenna damaged, corrosion at antenna base, and water egress into coax and or connecters just to name a few". And he's tested ground planes of 8" in diameter and 48" square, both with good results.
Now I do not think that this is your issue. As your trial of an L2 dipole antenna, which is automatically balanced requiring no ground plane, would seem to bear out (see top paragraph). But I also have reservations of its output being bounced off that huge mirror of a stainless steel firewall... But an enlarged ground plane could act as a barrier to unwanted radiated RF in the cockpit.(see emergency blanket) As it does in metal skinned aircraft.

Statement 3: If you could find an owner with the same make and model of aircraft, and same headset, and antenna location. Experiencing no problems and that's willing to answer questions... I would grill him relentlessly about his transponder, coax, and antenna installations down to the smallest detail. Until I could uncover the difference between the two builds. Keep in mind, even something as trivial as paint primer can make a difference. A bonus if he flies it over for a side by side comparison.:D




Bonus: Confused about transponder ground plane sizes and efficiencies...? You've got to read this thread! HERE!
Pay particular attention to Gary Millers offerings and pdf. attachment!

With best regards,
 
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RV aluminum aircraft update...

As interesting and bringing new problems and issues to light in composite and graphite airplane builds...as well as ground plane issues.

The 2 RV aircraft noise issues posted have not been ignored.


To Update:


Jeff Kersey's RV-7A --- In conversations with Jeff the cause of the problem appears to be very straightforward.
His installation did not keep the required 36" minimum distance between the transponder and transponder antenna. To be fair it was an upgrade, keeping the existing antenna location which is just behind the firewall between the exhaust pipes... That said, I'd read about a fix for other RFI problems with the Transponder being close to the antenna in installations where they where in very close proximity to each other, all though installed in the tail. That fix being to increase coax cable length to add impedance. Suggested this to Jeff, as well as double checking ground plane grounding connections... At this time Jeff is living with the low noise problem as is...

J-Red's RV-6A--- Now Jon's symptoms seem to be a bit different. Noise every few seconds or intermittent blips...But the real kicker is that it only happens during full throttle! So in conversations I brought up things that come to mind:

Vibration...any thing loose... especially grounding wise?
Voltage...Staying in spec?
Throttle cable...rubbing on anything? (long shot)

But my biggest suspicion would be where the transponder antenna is mounted. Greater than 36" line of sight from the transponder? (thinking the antennas in front of your feet) Anyone see a pattern with this?
From another thread it is also known that he's got a long GPS antenna coax run, so I asked.
And did you shorten up that long 16' RG-174 GPS coax cable to 5'? Or have it coiled up well away? (thinking it's antenna is up front) Thinking also perhaps it's gathering some RFI. As of today no reply...But he also stated that the problem is not a high priority or concern as it only happens during full throttle.

Best regards to all,
 
Hey T.C.

>> did you do all testing after making changes in the air?

To the extent possible, yes. I cannot walk around the airplane in the air :)

Also tried everything in the hangar and outside as the metal building *might* have had an impact.

>> RFI Barrier ... Feel like giving it a go?

Well, not really. I have the exterior in final paint and my interior is finished. I have looked into shielding options. Metallic paints, fine wire mesh, etc. I talked these over with my engineers and the engineers at Bose. They did not give me hope in finding a solution. Luck would be involved and most likely many attempts would be needed.

>> Ground plane

I've tried multiple ground planes of varying sizes and shapes. I even tried different locations. I would have been encouraged if I saw any change in the problem. The static did not seem to change for any configuration.

>> Coax?

I used a dummy load to isolate the source of the static. With the dummy load connected to the transponder, there was no static. I then connected the coax back to the transponder and the dummy load to the end of the coax. There was no static. If the static was being generated in the coax, it would have been there during this test.

I see you have been working with the RV guys and helping them. Good on you!

It seems the RV-7 seems to be good-to-go. I am happy for him. My understanding is the best chance at improving the situation is to move the transponder antenna. There is no formula for the correct distance or location, but moving it offers a chance. I would argue that it was the new position of the antenna rather than the length of the coax.

As for position of the antenna, there are a number of Velocity guys that mounted it directly under their seat or in the nose. They don't seem to be experiencing the problem. I tried mine in the nose and it didn't seem to help.

I would love to try another transponder just to see if it worked...

Andy
 
Not sure this is helpful but my Dynon 261 (Trig 22) XPNDR is installed on the right side of the sub-panel in my -7A with about 3' of RG-400 routed down to the antenna, which is located just in front of the gear weldment. The ADS-B IN box and antenna are on the opposite side.


Also have dual SV 1000T screens with Dynon radio and intercom.


No issues with static.
 
Here's an easy test. Repeat the dummy load test with a bad dummy load, e.g., solder a 25 ohm resistor (not wire-wound!) across a female BNC, and plug that into your coax instead of the antenna. If your symptoms return, then high SWR in the coax (bad match at the antenna, ground plane,...) is the problem. (make certain your transponder doesn't automatically protect itself by shutting down.)
 
I would argue that it was the new position of the antenna rather than the length of the coax.

Let me clarify. I read in a thread which the remote transponder and it's antenna were both mounted in the tail, and having interference problems from transmitter back feed. A workaround of increasing coax impedence by increasing it's length was successful.:)

As for position of the antenna, there are a number of Velocity guys that mounted it directly under their seat or in the nose. They don't seem to be experiencing the problem. I tried mine in the nose and it didn't seem to help.

I re-iterate...If you could find an owner with the same make and model of aircraft, and same headset, and antenna location. Experiencing no problems and that's willing to answer questions... I would grill him relentlessly about his transponder, coax, and antenna installations down to the smallest detail. Until I could uncover the difference between the two builds. Keep in mind, even something as trivial as paint primer can make a difference. A bonus if he flies it over for a side by side comparison.

I believe in LUCK. But I also believe you make your own luck...;)

And along Bob's suggestion...N49ex has mentioned that he has some ferrites that go over your coax cable if you'd like to give that a try. Give him a P.M.

Good to hear from you Andy, and that you still have your sense of humor.:D
 
Hi Ray,

Now that's a close install! Definitely under the 3' recommended distance.

What ANR headset are you using? Or just passive?

What antenna are you using?

Thanks for the input! The more points the better! Perhaps the distance between the audio panel and transponder is more/or just as important as that between transponder and antenna...?? The search continues...

Best regards,
 
I'm following this one with interest - from my experience with RF, ferrites on the coax as well as the audio lines will help. Also adding them to any power lines that feed power to the intercom as well so that no RF is picked up by the DC power going into the intercoms amplifiers too.

Cheers,
Matt
 
Hi Ray,

Now that's a close install! Definitely under the 3' recommended distance.

What ANR headset are you using? Or just passive?

What antenna are you using?

Thanks for the input! The more points the better! Perhaps the distance between the audio panel and transponder is more/or just as important as that between transponder and antenna...?? The search continues...

Best regards,

I have a passive Halo headset and a passive ATS on the co-pilot side but others have flown in my plane with Bose X and Bose A20 headsets and did not hear noise.

Both antenna are from ACS. XPNDR and ADS-B

Here is a pick of my sub-panel. Note the ground bar in the lower center. That is where all audio related grounds are united. There is a 18g wire from there to the main ground point on the firewall.

lHTqAxgh.jpg
 
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Note the ground bar in the lower center. That is where all audio related grounds are united. There is a 18g wire from there to the main ground point on the firewall.

Hi Ray,
Great post! An excellent textbook example of ground loop noise elimination. All audio wiring shielded and terminated here also?
Would you consider sharing your wiring diagrams for the main power and grounding distribution? In particular where you grounded the transponder and avionics...

With the Trig 22 on, and transmitting on the ground. Can your friend with the Bose A20 headset, on battery power, and ANR. Walk around the aircraft and pick up any noise? And if so, does sitting in the aircraft stop the noise? Or plugging the headset in?

Best regards,
 
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Another data point. I asked Tim Hass at Approach Fast Stack if he had a 330ES on the shelf. He did and he was willing to send it to me for a test. I put the new unit in the panel and there was no change in the static.
 
I just got off the phone with Mack Dickson at EAA. Mack met with the FAA and industry guys Wednesday. The FAA representatives were not engineering or systems savvy and were unaware of the issue. The rep. from L3 said "Yes, we know about that."

Having Mack hear confirmation from someone else is a step in the right direction. When I first spoke with Mack he was completely unaware. The old line "to solve a problem one must first admit there is one." Before EAA will advocate they must be convinced the problem exists.

I am feeling more confident that Mack gets it. This is more than one squeaky wheel.

Mack is in a bit of a catch 22 situation. He really wants to know how many people are noticing the issue. However, he doesn't want to ask the membership as he will be pointing out a problem that he does not have an answer for. Gotta know how many, don't wanna to ask...

I asked him to please speak with Steve at Garmin. Steve is a great friend to the experimental community and knows his stuff. He is very familiar with this subject and would like to see solutions on the market.

Both EAA and AOPA have expressed a *hope* the market would drive a solution. I don't know how this can get started as neither organization is willing to publish anything that acknowledges it.

I showed him the response from Bose stating they met the TSO and fixing this will require a new engineering effort. This will be expensive and they are unwilling to do at this time. I know changing the regulation will be a slow process, so let's get started. I think this might be where we are headed. Time will tell.

That's the update for now.

Andy
 
Another One!

I have this problem too. I have a Trig TT22 transponder (1090ES) on a VariEze. But, I guess I am somewhat lucky because it is silent when I use a passive headset, so my GTR-200 and its intercom appear to be immune. But, when I turn on ANR on either of my two models of Lightspeed headsets, I can hear the clicking.
 
I have this problem too. I have a Trig TT22 transponder (1090ES) on a VariEze. But, I guess I am somewhat lucky because it is silent when I use a passive headset, so my GTR-200 and its intercom appear to be immune. But, when I turn on ANR on either of my two models of Lightspeed headsets, I can hear the clicking.

Hello Ron,

Yes, that is consistent with my experience. Neither my GMA 245 audio panel or GTR 200 radio pick up the squitter in my Long-EZ with the ANR part of the headset turned off, but when you power on the ANR circuitry in the Zulu headset, you hear the 1090ES squitter coming in through the headset.

The same headset and avionics used in our RV-7A doesn't have the issue, presumably due to the extra shielding provided by the metal fuselage.

Steve
 
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I have this problem too. I have a Trig TT22 transponder (1090ES) on a VariEze. But, I guess I am somewhat lucky because it is silent when I use a passive headset, so my GTR-200 and its intercom appear to be immune. But, when I turn on ANR on either of my two models of Lightspeed headsets, I can hear the clicking.

I just installed a Trig22 in my RV-10. Made the first flight with the new transponder over the weekend. I didn't notice any clicking with my Bose with ANR enabled.

Not making any statement, just sharing a data point.

bob
 
ADSB static

Hi Andy, Thanks for stepping up and getting the ball rolling on this issue. I thought it was just my problem. I have a professionally wired full IFR, RV6 with recently installed Garmin GTX-335. I'm using Bose A20's. The static can be heard at low RPM's. The cruise RPM noise drowns it out. I went with Garmin and Bose to reduce chances issues like this. We need to keep the pressure on, hopefully sombody will come up with a fix. One thing I'm sure of is that it has nothing to with a composite designed aircraft. Thanks, Chip
 
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