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.

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. 

Regards,

Bob

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.

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.   

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?  

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

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

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.

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 rlbenji1@gmail.com

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.)

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.

 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.  

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.

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

The Avidyne trays are very robust, and better built.

* Orest

 This radio replaced a Garmin GTR 200 using the original comm antenna and coax, the reception with the 440 is poor at best. 

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?

Thanks

Neil

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.

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.

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.

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

I know this is an old thread but I'm experiencing poor reception on the IFD440, replaced the COAX which was RG-58, now it is shiny new RG-400, no improvement, tried 2 different antennas, no improvement.

I'm going to work with my IA to test the VSWR (Avidyne wants this even though VSWR has very little bearing on reception).  We'll be using a "Sark-110 Antenna Analyzer" and provide the report to Avidyne.

This radio was a slide in replacement for a GNS430W, the 430W had no issues with receiving, even before replacing the antenna coax.

Jeff

After these repairs my radios have been flawless and super clear.

I believe I had a similar issue.  The issue was resolved when I changed the engine and redid the alternator, alternator wiring, ignition harnesses, overhauled mag, and more.  I can't isolate what fixed it since I did a bunch of work at once, but my theory was that the IFD was auto squelching such that I couldn't always hear with with the IFD radio when I could hear with the KX-155.

I have no noise whatsoever in the other radio, plus the antenna for the IFD is even further away from the engines than my #2 radio.

working with my IA I've sent over VSWR reading (VSWR of 2.20 from 118 - 136) to support which was taken from the front of the tray (pulled the radio and pushed a BNC female plug onto the connector in the tray) so I have the VSWR from the connection the radio uses through the coax to the radio. Support is looking for some logs now, hopefully I can get them tonight before my friend borrows the airplane for the weekend. 

If it matters, when I had the VSWR meter connection I performed also did TDR to get the cable length, the total length was just under 12 ft, (13 ft minus the 1 foot lead on the tester), cable is brand new RG400.