GTN 750 650 Squelch & Fuel flow

[RocketAviator]

Myself & at least one other Mooniac' I met at homecoming are having problems with out Comms the 750 seems to be the worst. Have had the Squelch adjusted in the maintenance utility from 0 to 75, seemed to help for less than an hour then the problem returned!

Also is anyone else using the G4 and are you able to get Dynamic real time fuel flow on the 750, what about MP does anyone display that on their 750?

Going to call Garmin Monday myself but would appreciate any input from anyone with first hand experience .

Thanks in advance,

LLL

[Marauder]

Lacee -- First on the Garmin Comm. There are several Comm updates from Garmin that I was notified about. I thought one dealt with squelch issues. I will pull them up these evening when I get out of the coal mine later today. To be honest, I am not at all impressed with the GTN Comm radios. I have dealt numerous times with not being able to speak to ATC and had to rely on my 20 year Narco to establish communication. Not sure it is the belly mounted antennae or what exactly the problem is, but they can't hear me consistently.

 

As for the fuel flow. There was a firmware update that disabled the fuel flow on the Garmin. When my GTN was installed in December 2012, I was getting fuel flow on the Garmin from output from my EI fuel totalizer. After revision 3 (I think, again once I get the coal dust off of me, I will look it up) was loaded by my shop, my GTN fuel flow stopped working.

[Bennett]

Funny this should come up on the forum. My GTN 650 comm works perfectly, but my GTN 750 occasionally sounds a bit "scratchy", and then works perfectly a few minutes later. Too random so far to find a pattern, but I have a feeling it is in the squelch arena. I haven't done any GTN firmware (or operating system) updates lately, only database updates. Not a problem - just an annoyance, but annoyances can become problems. 

[BobAustin]

May be unrelated but...I have had Garmin 430 and 530 in two different planes, both with a King KR-155/165 NavCom.  When flying over areas with poor coverage the 155 /165 always is more sensitive both transmitting and receiving.  This repeated in over 50 trips or more.

 

In my opinion Garmin radios are for close to the airport use only.

[flyboy0681]

I too had the fuel flow problem and it was introduced in release 3 of the software and was fixed with the subsequent update.

I have to be quite honest, I've never had an issue with the radio on the 750. Be it transmit sensitivity or squelch.

[Piloto]

May be unrelated but...I have had Garmin 430 and 530 in two different planes, both with a King KR-155/165 NavCom.  When flying over areas with poor coverage the 155 /165 always is more sensitive both transmitting and receiving.  This repeated in over 50 trips or more.

 

In my opinion Garmin radios are for close to the airport use only.

 

I have a GNS 530AW and KX-165. The 530 measured 20 Watts and the KX-165 8 watts on the bench for transmitting RF power. However when the 530 was first installed the modulation level was lower than the 165. I readjusted the modulation level on the 530 and never had a problem reaching over 100nm at altitude. The modulation level can be adjuted on the COM Setup page MIC level or in some thru a pot on the enclosure labeled MIC. The adjustment needs to be made on three frequencies. You will need some form of TX modulation level monitor for this. The test needs to be made on your plane with the microphone you use. Check with an avionics shop for this.

 

José

[donkaye]

I have been using my new panel for over 46 hours now.  No issues with the squelch on either the 750 or the 650.  Set it up with 75% on the squelch level as recommended on the BeechTalk list.  When interfaced with an external  source, the 750 shows real time fuel flow information on the fuel and trip planning pages.  I could only get it on the 750, since all I/Os were already in use.

 

Have never had a complaint from ATC on any of the new radios.

[BobAustin]

Jose,

 

Thanks for the tip I will have my avionics shop check my 430W as you suggest.

Bob

 

I have a GNS 530AW and KX-165. The 530 measured 20 Watts and the KX-165 8 watts on the bench for transmitting RF power. However when the 530 was first installed the modulation level was lower than the 165. I readjusted the modulation level on the 530 and never had a problem reaching over 100nm at altitude. The modulation level can be adjuted on the COM Setup page MIC level or in some thru a pot on the enclosure labeled MIC. The adjustment needs to be made on three frequencies. You will need some form of TX modulation level monitor for this. The test needs to be made on your plane with the microphone you use. Check with an avionics shop for this.

 

José

[PTK]

Never had any issues with com radio or ff on the 750.

Could it be an installation related issue?

[RocketAviator]

Got the fuel flow working, needed to set up G4 & 750 for Shadin data format. Still having issues with Popping Squelch is what I'm told they call it.

Great to have large fuel flow displayed on 750.

[Marauder]

Got the fuel flow working, needed to set up G4 & 750 for Shadin data format. Still having issues with Popping Squelch is what I'm told they call it.

Great to have large fuel flow displayed on 750.

What version software do you have Lacee? Mine stopped working when they updated it to version 3 (I think). I will be taking it in for the glitchy display sometime. I do know that the version I have caused the FF to stop working.

[RocketAviator]

Latest version don't recall what it is. Fuel flow ok now that have both G4 & 750 talking Shadin data protocols.

The squelch is driving me crazy. One time I can hold my hand in front not touching of my audio it quits... i know sounds nuts so I video it so someone would believe me... changed the 750 audio panel... sill has the problem on the 750.

[Marauder]

Latest version don't recall what it is. Fuel flow ok now that have both G4 & 750 talking Shadin data protocols.

The squelch is driving me crazy. One time I can hold my hand in front not touching of my audio it quits... i know sounds nuts so I video it so someone would believe me... changed the 750 audio panel... sill has the problem on the 750.

Post that video on YouTube. Other than some nuts that come out of the woodwork on YouTube, there are people who may shed some light (sound) on the situation. Have you eliminated headsets?

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[flyboy0681]

What version software do you have Lacee? Mine stopped working when they updated it to version 3 (I think). I will be taking it in for the glitchy display sometime. I do know that the version I have caused the FF to stop working.

 

There is a known software bug with v3.0 in the area of fuel flow which was corrected in 4.0

[Marauder]

There is a known software bug with v3.0 in the area of fuel flow which was corrected in 4.0

Thanks for the confirmation. My JPI 830 and EI FP-5L both report fuel usage, but it would be nice if I could get it functioning again in the GTN. Do you know what the current rev is?

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[flyboy0681]

Thanks for the confirmation. My JPI 830 and EI FP-5L both report fuel usage, but it would be nice if I could get it functioning again in the GTN. Do you know what the current rev is?

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Actually, the fuel display was fixed in release 4.10

 

http://static.garmincdn.com/pumac/190-01007-11_0A_Web.pdf

 

 

The current release is 5.0. Here's the update document:

 

http://static.garmincdn.com/pumac/190-01007-12_0A_Web.pdf

[Mooney_Allegro]

I've been having constant issues with my new GTN-650/750. Here are the issues & I wonder if others are also experiencing the same thing?

** 650/750 squelch break. 650 is so bad on all frequencies you cannot monitor it. Up to 45 second squelch breaks on the 650 w/RX showing during the squelch breaks. The squelch breaks happen right after liftoff. I consider the 650 unusable.

** GTN 650/750 range issues 20-40 miles away having difficulty picking up approach/centers. This happens at least once during an IFR 2-3 hour flight. The 750 is worse, so you have to keep the 650 & 750 on the same frequency to be sure you don't miss a transmission, however, you have to keep the volume very low on the 650 due to constant squelch breaks.

** squelch break at end of every inbound transmission both on the 650/750. The squelch break lasts 1 second, but it's very annoying.

** Constant screen flicker for the 650.

I've been to 2 Garmin dealers, who adjusted my squelch with no positive effect. I'm also up to date with the latest com software 2.13 & the service bulletin where you had to send the units back to Garmin for a Mod. My squelch settings are both at 75, & the GMA35 is set to the factory default of 48%. I've also contacted 2 service techs at Garmin back in April, and the latest was this month & both techs told me they would get back to me within 24 hours with a solution & they never called me back after speaking to them with my concerns. A few Garmin dealers told me that they are having squelch & range issues with the later models. I'm not happy with Garmin Customer support, since nobody is getting back to me as promised. I'm just wondering if others have these issues & what is the solution. I has the 430 & 530 previously with none of these issues except for the flickering screen issue on the 430.

[Marauder]

** GTN 650/750 range issues 20-40 miles away having difficulty picking up approach/centers. This happens at least once during an IFR 2-3 hour flight. The 750 is worse, so you have to keep the 650 & 750 on the same frequency to be sure you don't miss a transmission, however, you have to keep the volume very low on the 650 due to constant squelch breaks.

** Constant screen flicker for the 650.

.

I have the two issues above with my 650. In fact, it's so bad I don't use the 650 to communicate with ATC. The range absolutely sucks for the ATC frequencies. I use my 20 year old Narco instead. I also have the flicker problem.

[Mooney_Allegro]

Marauder, have you contacted Garmin about the range issues with your GTN-650? Do you remember what your squelch is set to? I received an email from Garmin about the flickering issues, and they said there will be a software update at some point to address it. I've heard nothing from Garmin about the squelch break or range issues.

[Marauder]

Marauder, have you contacted Garmin about the range issues with your GTN-650? Do you remember what your squelch is set to? I received an email from Garmin about the flickering issues, and they said there will be a software update at some point to address it. I've heard nothing from Garmin about the squelch break or range issues.

I have had it looked at by the installing shop thinking it was an installation issue. They found nothing. I have not contacted Garmin but will do so now that I know there is someone else out there with this issue.

I don't have the squelch issue but do have the flickering display. They sent a letter out on this saying it would be addressed in a further release. I will take a look at the squelch setting when I get out to the airport.

Oh Peter -- you reading this? Superior product?

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[RocketAviator]

I sent a copy of this thread and some other research points like the Beach & Cessna sites where others are complaining of same or similar issues to my avionics guy, I had diner with the Garmin rep for Texas during the San Marcos AOPA, he told me to contact him if things did not get worked out. The next day my avionics guy had a new Garmin 750 installed, all was good for about 1.5hrs of flight then the squelch or always TX issues resumed. The avionics guy said maybe it is the audio panel so we air freight a new one of the PS8000 in and that did not fix it. In fact a real weird issue occurs I noticed after we installed the new 8000 when I was reaching up to the 8000 the TX light woukd come on the 750.... Now before you go off on me I video this several times. I don't even have to touch the 8000 for the action to take place. Now that being said put the old unit back in and it would not do it!

Also it worked very well for months... Then slowly things went south to a point the GTN 750 is not useable. I'm not a happy camper with as much as I spent, I'm so far very happy with my avionics guy he has not tried to pull my chain and tried all that I have asked of him. And for that I'm thankful.

Just wish we could all figure these issues out for me that is why I went the extra expense for Garmin! Wow I bet I open up a can a worms for that comment!

Let me know if anyone learns anything that might help and I'll do the same.

[flyboy0681]

I sent a copy of this thread and some other research points like the Beach & Cessna sites where others are complaining of same or similar issues to my avionics guy, I had diner with the Garmin rep for Texas during the San Marcos AOPA, he told me to contact him if things did not get worked out. The next day my avionics guy had a new Garmin 750 installed, all was good for about 1.5hrs of flight then the squelch or always TX issues resumed. The avionics guy said maybe it is the audio panel so we air freight a new one of the PS8000 in and that did not fix it. In fact a real weird issue occurs I noticed after we installed the new 8000 when I was reaching up to the 8000 the TX light woukd come on the 750.... Now before you go off on me I video this several times. I don't even have to touch the 8000 for the action to take place. Now that being said put the old unit back in and it would not do it!

Also it worked very well for months... Then slowly things went south to a point the GTN 750 is not useable. I'm not a happy camper with as much as I spent, I'm so far very happy with my avionics guy he has not tried to pull my chain and tried all that I have asked of him. And for that I'm thankful.

Just wish we could all figure these issues out for me that is why I went the extra expense for Garmin! Wow I bet I open up a can a worms for that comment!

Let me know if anyone learns anything that might help and I'll do the same.

 

Truly bizarre. My 750 was installed in 2011, has software version 4.0 and I don't have any problems with it. None.

[Marauder]

I sent a copy of this thread and some other research points like the Beach & Cessna sites where others are complaining of same or similar issues to my avionics guy, I had diner with the Garmin rep for Texas during the San Marcos AOPA, he told me to contact him if things did not get worked out. The next day my avionics guy had a new Garmin 750 installed, all was good for about 1.5hrs of flight then the squelch or always TX issues resumed. The avionics guy said maybe it is the audio panel so we air freight a new one of the PS8000 in and that did not fix it. In fact a real weird issue occurs I noticed after we installed the new 8000 when I was reaching up to the 8000 the TX light woukd come on the 750.... Now before you go off on me I video this several times. I don't even have to touch the 8000 for the action to take place. Now that being said put the old unit back in and it would not do it!

Also it worked very well for months... Then slowly things went south to a point the GTN 750 is not useable. I'm not a happy camper with as much as I spent, I'm so far very happy with my avionics guy he has not tried to pull my chain and tried all that I have asked of him. And for that I'm thankful.

Just wish we could all figure these issues out for me that is why I went the extra expense for Garmin! Wow I bet I open up a can a worms for that comment!

Let me know if anyone learns anything that might help and I'll do the same.

Lacee -- I am calling my avionics shop this afternoon and will ask how many others are running into issues. For the record, I have a GTN 650 connected to a PS 8000BT. I have not seen the squelch issue. Installed December 2012.

BTW - got the adapters! Thank you! Will try them this weekend.

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[Mooney_Allegro]

I spoke to Sarasota Avionics today, who did my GTN-650/750 install, & the GMA35 remote audio panel. Garmin has decided to replace both of my GTN's under warranty due to the squelch & range issues. Like I said before, the 650 is useless due to intermittent squelch breaking which lasts up to 45 seconds on all frequencies.

RocketAviator, that's very interesting about your TX indication coming on when you reach your hand up towards that audio panel. Did you mean RX indicator instead of TX? My RX comes on when the squelch breaks. Also, do you have range issues as well?

Dave

[RocketAviator]

I spoke to Sarasota Avionics today, who did my GTN-650/750 install, & the GMA35 remote audio panel. Garmin has decided to replace both of my GTN's under warranty due to the squelch & range issues. Like I said before, the 650 is useless due to intermittent squelch breaking which lasts up to 45 seconds on all frequencies.

RocketAviator, that's very interesting about your TX indication coming on when you reach your hand up towards that audio panel. Did you mean RX indicator instead of TX? My RX comes on when the squelch breaks. Also, do you have range issues as well?

Dave

My bad yes RX, not TX. Don't know if I have range issues as the radio is unusable when breaking squelch.

Someone posted how to test range or maybe not range rather power / signal output strength but I have not had this checked. Garmin & my avionics shop have already replaced the 750 with a new one but the problem did not go away. That is most concerning to me and possibly suggests one of two probabilities. 1 Garmin has some product issues and I list this one first as I have account of several people who are having issues and 2 that there is some other issues such as shielding or other anomalies that can cause the Garmin to believe there is radio transmission again to me that may be Garmin related more than not. I'm a bit of a nut when it comes to learning what the cause of a problem is and often won't accept plug and replace without reasonable identity of the culprit. But in this case I just want the problem to go away and that is why I choose the higher cost Garmin in hopes this type of issue would not occur if in fact it is a Garmin issue.

Please let me know if the change out resolved you issues.