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Occasional Com Radio Issue

Printed From: Avidyne
Category: Avidyne General
Forum Name: IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
Forum Description: Topics on Avidyne's IFD 5 Series and IFD 4 Series Touch Screen GPS/NAV/COM
Printed Date: 20 May 2019 at 6:53pm
Software Version: Web Wiz Forums 12.01 -

Topic: Occasional Com Radio Issue
Posted By: B2C2
Subject: Occasional Com Radio Issue
Date Posted: 16 May 2018 at 3:51pm
I have had an on and off problem with the radio quality on my 540 for a year or so and was wondering if anyone else has seen this. Once in a wile, I believe after a bit of a sit but haven't had it happen often enough to verify this, I will get comments from ground etc that my 540 com radio is 1 by 5. Reception is fine. I have two radios so I switch to the other one and all is good. Then it seems like after I power cycle the unit, typically next startup on the same day after a flight somewhere its fine. As you might imagine its not easy to diagnose this when the avionics shop is at another airport. So far it seems like it goes away by itself and I haven't been able to get it to do it at the shop. We checked all antenna connectors, tray etc and no obvious problems found. Has anyone else seen anything like this or have a suggestion of what might be causing it?    

Posted By: AzAv8r
Date Posted: 16 May 2018 at 10:53pm
I have had two incidents of something similar, both in mid February of this year.  The IFD was installed ~ Jul 15.

The first time I was contacting Ground for a day VFR departure, sitting near our hangar.  After several tries with no response, Ground replied "Aircraft repeatedly attempting to contact ground, nothing but a squeal." I switched to #2 (a Garmin SL30), Comms was fine, and we departed.  Later in the flight I did a radio check on the IFD with ATC and all was well, so we used the IFD for the remainder of the flight.  I attributed the issue to having the perfect (unlucky) position in an aluminum (hangar) canyon, out of line-of-sight from the tower, to maximize any of a number of RF distortions (I started life as a radio engineer).

Three days later departing a different airport, and sitting on a wide-open ramp in clear line-of-sight to the tower, Ground replied to my initial attempt "weak and unreadable".  I again switched to #2, and was successful.  We departed VFR on #2.  After a while in the flight, we switched back to the IFD and did a radio check with ATC.  No issues, so we used #1 for the remainder of the flight. 

Subsequent flights have revealed no issues.   Still scratching my head, and wishing I'd bought a lottery ticket.   Right now I'm assuming a defective antenna connection somewhere, but intermittent problems are difficult/expensive to track down until you discover the magic sequence that makes them repeatable.

Posted By: HenryM
Date Posted: 16 May 2018 at 11:16pm
i had a similar problem in a non-IFD-equipped plane. The root cause in my case was a loose ground connection. I accidentally found it when I touched a nut on the firewall that turned when it was supposed to be tight. We had spent a couple of hours chasing the bug right after an engine monitor installation in a Cessna 172. We were chasing leads related to the engine monitor installation which had not even touched the area where the loose ground was found. 

The loose ground caused the radio signal to react as described. Fortunately the ground was loose enough that it was not as intermittent as the problems described here. 

Posted By: PA20Pacer
Date Posted: 17 May 2018 at 7:07am
You have probably already thought about this, but often the #1 comm is wired to an antenna on the bottom of the plane. On the ground, it is possible for the plane to be positioned so that a wing or another part of the airframe is blocking the signal.



Bob Siegfried, II
Brookeridge Airpark (LL22)
Downers Grove, IL

Posted By: compasst
Date Posted: 17 May 2018 at 11:39am
I experienced transmission clarity issues on my first IFD 540 shortly after it came out. Turns out it was a problem that required warranty work.

I knew it wasn’t antenna issues because the previous radio worked fine on same antenna and wiring.

Give tech a call and ask for Christine.

Posted By: B2C2
Date Posted: 18 May 2018 at 7:49pm
Ill try calling tech support. Given the extremely intermittent nature of the problem I'm not sure what they will say but its worth a shot. When you had this problem that was fixed under warranty was it also intermittent or predictably present?

In regards to one of the previous posts when I had the problem the other day i tried the radio again from a different spot on the field prior to departure to see if I was being blocked on the antenna due to the hangars nearby and had the same problem. Next time I'm going to power cycle the radio stack and see if it fixes it. I had a passenger with me and didn't want to unduly delay the flight with trouble shooting.   

Posted By: Plunger
Date Posted: 24 May 2018 at 10:33am
I have a new IFD 440 with a different problem and can't get Avidyne Tech support to help me with. My situation is that the comm radio in the 440 has poor reception.I compare it to the comm 2 which is a 20 year old radio which receives perfectly. I swapped the antenna cables, for both radios but that didn't help. Next the avionics shop swapped out the 440 with a new unit off the shelf but the reception was still poor with the replacement radio. Next we reinstalled my old Garmin 430 and the reception was perfect.I have not replaced the coax cables or antennas yet.

Not sure what to do now. Rolland from Avidyne won't return my calls, the Avionics Place in Rockford is stumped. Not sure Avidyne was a good choice.

Anyone have any ideas?  

Posted By: oskrypuch
Date Posted: 24 May 2018 at 1:34pm
I have never heard of anyone (customer, or shop) not getting return calls from Tech support, when they had an outstanding problem.

There is no general issue with the IFD COM section, if there was, it would have shown up a long time ago.

The thing that is common here would be the mounting tray. The fit on the IFD and GNS are a little different. I would bet that replacing the tray (if you didn't use the nice new IFD tray), might solve the problem.

Just a guess.

* Orest

Posted By: Plunger
Date Posted: 24 May 2018 at 2:18pm
Orest, Thanks for the response I don't believe that Avidyne has an answer to this problem so it seems that their solution is to just ignore me.I went with the 440 so that I would not need to replace the tray and all of the expense associated with replacing my Garmin unit.

One theory that has been suggested is that possible the coax antenna cables could be the problem. Any thoughts?

Posted By: Gring
Date Posted: 24 May 2018 at 2:24pm
did you check to see if your squelch is on?  That will cause comm issues.  Aux page and audio tab.

Posted By: Plunger
Date Posted: 24 May 2018 at 2:35pm
I have played with the squelch and don't believe that is the problem. Any signals will break the squelch much sooner on my old Bendix King (comm 2) before it will on the new 440. I turn off the squelch and I can hear a faint staticy signal while the comm2 is already receiving well.As I get closer to the signal source the reception improves but never gets a good as the old comm 2

Posted By: oskrypuch
Date Posted: 24 May 2018 at 4:21pm
Originally posted by Plunger Plunger wrote:

One theory that has been suggested is that possible the coax antenna cables could be the problem. Any thoughts?

Well, yes, something related to that or its connection to the new unit.

Has your shop tried to bench test the units? Any good avionics shop will have the tools to measure output. But rather unlikely that there were two faulty 440s in a row.

* Orest

Posted By: Plunger
Date Posted: 24 May 2018 at 5:31pm
The avionics shop did test with a power meter but not sure if that test will tell anything about reception. Tomorrow I will fly and see if I can get data on the transmitt quality. I have not had moments about the transmitt quality. So far I only know that reception is poor. I should know more tomorrow.

Posted By: B2C2
Date Posted: 25 May 2018 at 3:50pm
I am not an install tech but suggest the following. Since two units both behave the same its almost certainly not the 440. It looks like the radio connects through a bulkhead pass through connector at the back of the tray. The antenna coax connects to the opposite end of this connector outside of the tray. I would suspect a problem with the IFD antenna coax connector to the tray bulkhead pass through connector connection. This could be caused by incomplete seating of the unit in the tray. It could also be that this bulkhead pass through connector is slightly out of spec or damaged due to the action of the Garmin unit on the connector. During one service visit with my 540 and an Avidyne tray the service tech had some trouble seating the 540 properly. its a tight fit. So I would double check the 440 is all the way seated. If that doesn't do it I would think about replacing the bulkhead pass through connector. These can be damaged and a poor connection will result in poor reception.   

Posted By: B2C2
Date Posted: 29 May 2018 at 1:05pm
So I had the same issue when I went to fly the plane this last weekend, but this time I power cycled the radio stack in the run up area. Radio then worked properly. Problem solved. So I do think its associated with power up after sitting and it can for the moment be fixed by power cycling the unit,however this is the first time I have had it happen on back to back flights. Time for that call to tech support. 

Posted By: Plunger
Date Posted: 03 Jun 2018 at 6:31pm
Is there anyone who knows what the part numbers are for the antennas that will work a IFD 440. This may be a long shot but an easy one to check for my poor reception problem. I Have not heard back from Avidyne in a while so will attempt to troubleshoot the comm problem.

Posted By: DavidBunin
Date Posted: 04 Jun 2018 at 4:14pm
I believe I used the CI-121 on mine.

Posted By: Gring
Date Posted: 05 Jun 2018 at 6:19am
The acceptable antennas are listed in the install manual available on the Avidyne website. 

Posted By: dmtidler
Date Posted: 05 Jun 2018 at 7:43am
The install manuals used to be publicly available on the Avidyne website...not anymore.

Posted By: AzAv8r
Date Posted: 06 Jun 2018 at 9:28am
Unlike with GPS, any good quality comm antenna should work fine, as long as it is intact/undamaged.  By far the most likely issue with an antenna system is in the coax cable (including grounding) between the transceiver and the antenna.  Cables have an "impedance" determined by their physical cross-section dimensions and materials, so distortion (eg, kink it or tie it in a knot) can dramatically reduce their ability to deliver RF power.   Cuts in the shielding (which isn't just a shield, but part of the transmission line) can have this same effect.   The first time I was deep inside our panel (actually, when the IFD 540 was installed) I discovered the transponder antenna cable had been abraded through the shield on one side, which I'm sure meant we weren't radiating full transponder power. 

For a transmitter, the bad thing about an impedance problem is that part of the transmitter power gets reflected back into the transmitter itself, which distorts what signal does get transmitted.    So when the problem does happen, ask the person giving you the radio check (after you've switched to the good transmitter) about clarity.   That's why there is an "and" in the traditional radio check response "Loud and Clear", "Loud and distorted", "weak but readable", "weak and unreadable", etc..

Any chance you can correlate the issue to temperature?  I've seen bad BNC connectors where the center pin would barely mate with the female socket.  As materials shrink when they get cold perhaps you have a center pin pulling out of a connector.

Since the problem is intermittent, I would suggest swapping antenna and cable systems at the boxes themselves.   So your #1 comm will use your #2 antenna and cable, and vice-versa.   Fly this way until the problem is observed again.  If it follows the antenna, you'll know it's in the antenna system.  If it follows the radio, you'll know it is in the radio, the tray, or any coax pigtail between the tray and where you swapped the antenna systems.

Posted By: Plunger
Date Posted: 19 Jun 2018 at 11:13am
I have waisted many hours attempting to troubleshoot the poor comm reception problem with out any success.Niether my avionics Shop or the Avidyne tech people can tell me why the comm reception on my new IFD440 is so much less than my comm 2 which is a 20 year old Bendix/King or my old Garmin 430.

I would ask anyone who has a newer IFD 440 and an exsisting comm 2 radio to help me out if you could.This is the procedure thatI use to test the comm reception. I simply tune a AWOS station on both radios that is quite far in the distance and start flying toward the transmitter. I keep flipping between the two radios and comparing the quality of the signal.

The difference in signals is like night and day doing this test.If anyone could do this test for me the next time you fly then I would know if I should keep looking for a solution or accept the poor quality of the product. 

Thanks for any help. Ralph Benjamin

Posted By: oskrypuch
Date Posted: 19 Jun 2018 at 4:08pm
I have not noticed any difference in my IFD540 and SL-30 radios, but I'll give that a try for you.

* Orest

Posted By: Plunger
Date Posted: 19 Jun 2018 at 4:16pm
Thank you so much

Posted By: AzAv8r
Date Posted: 19 Jun 2018 at 10:42pm
The weekend I had a transmitter reception problem, I switched back and forth between the receivers during my arrival and noticed no difference.  I will repeat this verification my next cross-country to confirm.

A difference in reception distance can be readily attributable to the squelch setting of the receiver.

The IFD squelch is adjustable; I don't recall how, but I recall adjusting it.   I know it's in the manual.

If someone were to adjust the squelch in an RF-noisy environment, you would not be happy when you actually used the radio.  Try adjusting the squelch when you are doing your AWOS test.   You should be able to get both radios to break squelch at the same distance, then you compare the clarity of the audio.

I have no reason to believe my IFD 540 is any less capable than my SL30, which I've heard others say is the best radio Garmin will ever build.  (And they discontinued it.)

Posted By: Plunger
Date Posted: 20 Jun 2018 at 10:19am
Thanks for the suggestions but I have tried the squelch adjustments.My avionics guy has worked on this problem for many hours and has done everything except replace the coax which he says is not the problem.Avidynes tech dept. also does not have an answer.

My only hope is that I can find others who have the same problem so we can go back on the manufacture and possibly come up with a solution.

Posted By: Catani
Date Posted: 20 Jun 2018 at 11:12am
Originally posted by Plunger Plunger wrote:

Thanks for the suggestions but I have tried the squelch adjustments.My avionics guy has worked on this problem for many hours and has done everything except replace the coax which he says is not the problem.Avidynes tech dept. also does not have an answer.

My only hope is that I can find others who have the same problem so we can go back on the manufacture and possibly come up with a solution.
Can you hot swap another IFD or 430 to check whether either improves the performance of your reception?  If the swapped radio works well, the problem is with your unit.  If no radio works well, the problem is with the rack, the wiring, and/or the antenna.

Posted By: Plunger
Date Posted: 20 Jun 2018 at 8:27pm
I have swapped out the problem radio with another brand new IFD 440 And the problem remains. I have also swapped out the problem radio with a Garmin 430 and the 430 reforms beautifully. It’s a real head scratcher.

 Not sure that Avidyne’s tech-support is going to continue with this problem. I may very well be on my own from this point out. Not very good advertising for them.  

Posted By: AzAv8r
Date Posted: 20 Jun 2018 at 10:17pm
Was the 430 you swapped the same one that came out, or was it a different one?  Looking up thread, I would infer this is likely the case.

The reason I ask:  while I have an IFD tray, it has been reported here that the robustness of the Garmin tray is lacking in comparison to the IFD tray.   If this is the case, it is conceivable that your (flexible) Garmin tray accommodated a dimensional non-conformity of your 430, and took a "set". (Or perhaps the original installer jury-rigged it to work).  These would explain the 430 vs 440 difference.

Posted By: Plunger
Date Posted: 21 Jun 2018 at 8:53am
The 430 was not my original unit but one that the avionics shop had on their shelf. Are you suggesting that I replace the original Garmin tray with the Avidyne tray?

Posted By: oskrypuch
Date Posted: 21 Jun 2018 at 10:57am
Originally posted by Plunger Plunger wrote:

The 430 was not my original unit but one that the avionics shop had on their shelf. Are you suggesting that I replace the original Garmin tray with the Avidyne tray?

I would in this instance, and believe I suggested that up thread.

The Avidyne trays are very robust, and better built.

* Orest

Posted By: Plunger
Date Posted: 21 Jun 2018 at 1:18pm
One of the reasons that I went with the Avidyne 440 is so that I would not have to replace the tray. This has been very frustrating

Posted By: Catani
Date Posted: 21 Jun 2018 at 5:37pm
Originally posted by Plunger Plunger wrote:

One of the reasons that I went with the Avidyne 440 is so that I would not have to replace the tray. This has been very frustrating
Well you don't, if the tray is a good one.  It's like the DFC90: all you need to do is replace the STec box, the DFC90 uses the same servos. But if the servos are marginal, the DFC90 won't work well.  Suitability of existing hardware is something a installation shop should check for.  Any existing piece of equipment is subject to prior wear and tear.  What you will still get by going with the IFD is that a new Avidyne box, if needed, will fit where the defective Garmin box went, and all the wiring will still be there.  It's not like a GTN650 install where you start from scratch because the size and wiring are entirely different from a 430.

Posted By: Plunger
Date Posted: 25 Jun 2018 at 9:56pm
No it’s not like the DFC 90.

Posted By: aviationone
Date Posted: 10 Aug 2018 at 1:20pm
I have the same issue with my new IFD 440. Waiting on Avidyne to look at logs.  If you come up with a fix let me know. I have inspected coax and connectors with no issues found. Did an SWR test on the cable/Antenna all numbers below 1.9. 
 This radio replaced a Garmin GTR 200 using the original comm antenna and coax, the reception with the 440 is poor at best. 

Posted By: Plunger
Date Posted: 10 Aug 2018 at 1:34pm
I have done all of the same things that you have done and have been working on this problem for about six months. Avidyne doesn’t know what to do anymore and is basically forgotten about me. If you make any progress I would really appreciate letting me know as I am out of options here. Good luck and I hope the Avidyne people will stick with you as they have not done so with me. My email address is RLBENJI if you would like to email me directly. Good luck 

Posted By: TogaDriver
Date Posted: 22 Aug 2018 at 4:45pm
I'm "hearing" different, but possibly related, problems with my IFD440.  My installation is one IFD440 and one (old) KX-165.  The intercom is a GMA-340.

When I first startup the aircraft with the GMA selected for the IFD I will sometimes get loud noise, as if the squelch is off.  Once I get through the startup and test/legal screens the noise usually goes away.

The other issue is with PTT:  often, when I press PTT when the IFD is selected I get a loud scratching/popping sound, as if the PTT switch is dirty or intermittent.  When I'm Tx'ing on the KX-165 I never get this problem so the IFD seems to be unusually sensitive to the PTT in my installation.  I plan to open up the switch on the yoke and blow it out to see if there is any improvement.

My question:  has anyone experienced either of these problems with the 440 or 540?


Posted By: HenryM
Date Posted: 22 Aug 2018 at 6:00pm
I haave a similar issue on my plane, but I have been attributing it to the audio panel.

I have an IFD-540 on COM1, and a TKM 300MX as COM2. They are connected to a PMA-6000M PS Engineering Audio Panel. 

 As long as only one com is selected, everything works as expected. However, if COM1 is the transmitter and I press the button to hear COM2, whenever I press the PTT I hear a loud noise, similar to the descriptions above. It sounds like some sort of audio feedback or loud background noise. If I deselect COM2 audio, then everything is fine. The issue does not appear if COM2 is selected as the transmitter.

Posted By: Plunger
Date Posted: 08 Sep 2018 at 7:03pm
have you had any success so far with your COM reception on your new Avidyne 440?

Posted By: Plunger
Date Posted: 08 Sep 2018 at 7:04pm
Aviationone have you had any success so far with your COM reception on your new Avidyne 440?

Posted By: ChainSaw
Date Posted: 30 Sep 2018 at 3:20pm
IFD 440 Users. Rule out the simple things first. Are you in the vicinity of a solar farm?  RF interference (RFI) stories with AM radios (i.e. aviation radios) follow in  the  context of IFD 440 'com issues'.Our locally famous pilot rented my plane shortly after my  ifd440 upgrade and returned to curse the com quality of the ifd440.  The A&P and I could not reproduce the problem. A few weeks later I had cause to fly the same route our famous pilot flew. The intercom, radio, and headset noise went crazy just as our famous pilot described . We ajustedd  all connections and the noise subsided gradually   and stopped. Back to normal. During  the noise episode, I  could barely hear my co-pilot. I mentally noted that  we  had just  flown over  a strange patch of upward facing black panels that do not appear on Google Earth. On the reverse leg,  the exact same noise phenomena happened and this time  I  confirmed that it started and stopped exactly at the boundaries of the presumed solar farm.  Subsequent research reveals many technical papers on the subject of RFI from solar arrays/inverters on AM radios - the type of modulation aviation radios use. However, none of the papers mention this RFI problem in the context of Aviation radios - yet. I am trying to pinpoint the location and will report it to the FAA in an attempt to get some aviation case studies started on the subject of solar farm RFI with general aviation radios.    

Posted By: safari
Date Posted: 30 Sep 2018 at 7:37pm
I have had the same problem with weak transmit and receive on 540 and 550 compared to kx155. I have switched the antennas and no luck it usually is only a problem with ground control when you are near some hangars but the other day switching to the next ATC frequency I could barely hear them and they couldn't hear me switched to the kx155 loud and clear and he said it was his problem not mine. which means they had a weak area but the kx155 is a much better radio from what I can tell Usually it is not a big problem and I only use the ifd but if a weak signal I will turn on the kx155 like to monitor atis a ways out much better reception on the kx155. I guess one could put a Garmin radio in place of it and see what happens. 


Posted By: Plunger
Date Posted: 01 Oct 2018 at 11:04am
Dave, You will find that if you slide a Garmin in the place of the Avidyne that your reception will be good. The Avidyne is just a poor radio.There is no fix to this problem, you will always have bad reception

Posted By: HenryM
Date Posted: 01 Oct 2018 at 1:33pm
I don’t have any issues with the radio of my IFD-540. It works just as well as the MX-300 2nd radio or the Icom and Narco radios I had in my previous 2 airplanes.

Posted By: Catani
Date Posted: 01 Oct 2018 at 2:57pm
I have an IFD440 and a 430W.  The IFD radio is the better radio than the 430W, for both transmission and reception.  I chalk up such things not to the quality of the box, but installation, cabling and antenna issues.  If the 430W did not work at all, I'd investigate.  But it does work, so I live with the difference.

Posted By: Plunger
Date Posted: 17 Oct 2018 at 10:32am
However my problem is that my new 440 has poor reception and my old Garmin 430 and 20 year old Bendix King are both good. Testing on the bench confirms that the Avidyne is a lesser unit that the other 2 radios.I am on my 4th 440 now and they all have had bad reception and the problem is not the install job. The last 440 that I had also over heated and shut down every few miniutes. I am very frustrated and Avidyne will no longer return my emails or phone calls. I have well over 2000 dollars in the trouble shooting process with 2 different avionics shops. Both shops say the same thing"the reception problem is in a poorly designed radio. Looks like i'm stuck with a 13,000 radio that dosent preform.

Posted By: forkauto
Date Posted: 17 Oct 2018 at 12:25pm
Have you swapped over to the Avidyne mounting tray. I know multiple people have mentioned this. When I got my 440 initially, I wasn't happy with the reception, swapped out the tray and voila it was working great. Like night and day! Since I have gone with the 550 after my panel upgrade. If you have not tried that, I would definitely recommend it. If you look at the two side by side, you can see the Avidyne unit is much heavier duty

Posted By: Plunger
Date Posted: 18 Oct 2018 at 8:26am
I would try swapping the tray but the bench testing indicates that the Avidyne 440 is the weak radio. Any idea how much the cost would be to change out the tray? the main reason that I went with the 440 was because of the ease of installation. 

Posted By: forkauto
Date Posted: 18 Oct 2018 at 10:49am
If I had to guess, I would say probably 3-4 hours of labor

Posted By: Plunger
Date Posted: 24 Oct 2018 at 11:49am
I have heard from several 440 owners that have identical com reception problems. Since the beginning I have been told that I am the only 440 owner that has this problem but now realize that is not true. If other 440 owners would compare the reception of their 440 against another com radio you may realize how poor the reception really is.
Avidyne will no longer return my calls or emails. That being said it seems that I am on my own. I have contacted most of the tech people at Avidyne but don't get the courtesy of a return call or email. I attempted to contact the CEO of Avidyne but was told that he does not talk the the customers which I thought was sad.
I realize  now that I made a big mistake by dealing with Avidyne. When I had my own contracting business I realized when a customer is happy with the work that you do for them they will tell 3 or 4 people what a good job you did for them but if you do poor work they will tell everyone that they know how bad your product and service is. That is where I am at after months of trying to resolve my 440 issues.
I hope that others don't make the same mistake that I did by buying an Avidyne product.

Posted By: programmer@pcmforles
Date Posted: 29 Oct 2018 at 10:45am
Honestly, I would try the tray, for as easy of a swap as it is (the wiring is the time consuming part, the tray isn't)
I put an IFD440 in a Garmin 430 tray and I fortunately had excellent luck with it and the IFD440 radio out performs the GNS430 radio.    
But, I just did an IFD550 install and am using the Avidyne rack, but the radio was not fully seating into the tray because the face of the radio was catching the front of the panel before it fully seated as I had the rack a bit too deep.   I had very poor radio reception and transmission until I fixed this issue.   I had a GX60 in before and it had good reception so I knew the antenna was good, I did have to change the connector from the solder on Apollo/UPSAT connector to a BNC and did that connection twice thinking that was the problem till I connected the BNC to my portable radio and realized it worked OK so I knew that wasn't the issue.
Just my $.02 that my help you fix your issues.

Posted By: oskrypuch
Date Posted: 29 Oct 2018 at 5:35pm
I concur, swapping out the tray would be the thing to try, only a few hours labor. There doesn't appear to be a design issue in the IFD COM radios, with thousands of units out there for a number of years now, if there was it would be obvious.

My IFD540 works quite well. The SL-30 I have as #2 is about the same in performance, and it is a very good unit.

If Avidyne even sent out three replacement units, looks like they did a yeoman effort. Even a modest non-connect of the antenna would explain your problems. The Avidyne trays are much better construction, for sure, try the tray swap -- very little to lose. 

* Orest

Posted By: programmer@pcmforles
Date Posted: 29 Oct 2018 at 8:46pm
Agreed.   I have also found before that if the BNC connector that is installed is not done properly the center contact does not stick out far enough and it will have an intermittent engagement with the backplate BNC connection.   I've accidentally done this before with the one crimper tool I had that I've since replaced.   On the IFD units the Com antenna connection is near the very top and often on a tight fit there is pressure on the com antenna coax with the glareshield or other things near the back of the firewall.   

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