Garmin GTN 6xx/7xx thread

[RotorDude]

Not sure if a generic thread exists, but wanted to add the latest Garmin advisory regarding boot failure after some checklist setups.

 

[petrolero]

I got that today as well. Sounds like the checklists work OK but adding a shortcut in either of those locations causes it **** the bed at bootup.\

Good to know for sure!

 

[RotorDude]

For those not aware of it Garmin has come out with a new free version of the GTN Windows desktop simulator. Apologies if this has already been mentioned here.

 

[Henning]

Nice, appreciated.

 

[Marauder]

Thanks for starting this thread. Since it is dedicated to the GTNs are any of you experiencing open squelch issues on some freqs?


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[RotorDude]

Thanks for starting this thread. Since it is dedicated to the GTNs are any of you experiencing open squelch issues on some freqs?

I have noticed that in the past on some frequencies (e.g. a year ago returning IFR from KEYW to KISM over the GoM), but it seems to have gotten better lately. I seem to recall they tweaked something in the software for that. Best way to diagnose it is with another independent radio, since if there is a strong noise/interference source on the frequency you can't blame the auto-squelch.

 

[tlglenn]

I spent about 20 hours with a GTN650 over the past two weeks. Only once do I recall a squelch issue and I wasn't sure if it was the unit or not.

Those traffic alerts are pretty handy. The GTN would issue the alert 2-3 seconds before ATC did so.

 

[Marauder]

I have noticed that in the past on some frequencies (e.g. a year ago returning IFR from KEYW to KISM over the GoM), but it seems to have gotten better lately. I seem to recall they tweaked something in the software for that. Best way to diagnose it is with another independent radio, since if there is a strong noise/interference source on the frequency you can't blame the auto-squelch.

I'm running the current COM firmware (2.20). The unit was installed in 2012 and was having some range issues but never an open squelch problem.

A few ago I started having issues on a number of frequencies. I started recording these and those that I didn't have an issue. Pretty frustrated with it at this point. Have an appointment with the shop to look at it again.


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[Henning]

I'm running the current COM firmware (2.20). The unit was installed in 2012 and was having some range issues but never an open squelch problem.

A few ago I started having issues on a number of frequencies. I started recording these and those that I didn't have an issue. Pretty frustrated with it at this point. Have an appointment with the shop to look at it again.


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Antenna issue?

 

[Marauder]

Yes I am. I thought it was just me. Some frequencies are worse than others. I called the avionics shop that did the install and he said there is a squelch adjustment in the setup section that he can tweak to see if it helps. I haven't gotten around to taking it in yet.

I have a number of frequencies that I recorded that are problematic. Most are in 124.xx to 126.xx. The Unicom freqs are okay as are the Center freqs in the 133.xx range.


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[Marauder]

Antenna issue?

I don't know either and it is frustrating. Easy enough for them to swap antenna. Worth trying, thanks.


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[Marauder]

Agree with your assessment. I was on freq with Tucson approach today (128.5) and there was a near continuous "mic keying" noise with the RX indicator displaying almost the entire time. When someone was talking the transmissions were very clear otherwise squelch problem was very distracting.

Has someone reported this to Garmin?

I think Garmin is aware. There has been a steady stream of Com firmware updates like the recently released 2.20 to deal with open squelch issues.

Service Bulletin 1526: GTN 635/650/750 Software Upgrade to COM Software Version 2.20
1 APRIL 2015 / SERVICE DOCUMENT NOTIFICATIONS /

CERTIFICATION APPROVAL: TSO Authorization

COMPLIANCE: Optional

SYSTEM: GTN635 / GTN650 / GTN750

PURPOSE:

This Service Bulletin announces the availability of GTN 635/650/750 COM Software Version 2.20 and COM FPGA Version 2.4.

GTN 6XX/7XX COM Software Version 2.20/FPGA Version 2.4 contain the following changes from COM Software Version 2.13/FPGA Version 2.2:

Reduced noise burst (“Squelch Tail”) that occurs at the end of a reception
Reduced random squelch breaks (popping)
Download 1526A_ASDN


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[RotorDude]

My guess regarding specific discrete frequencies that have a constant "open squelch" problem is that there is external interference injecting noise into the channel and causing that. I think this is unrelated to "squelch tail", which would affect pretty much all channels.
That interference could be emanating from anything electronic on board, with one suspect being the alternator/regulator. What I would do (and have done in the past) in such cases, is to turn off everything but the problem radio (e.g. turn off the alternator field), and pull all available circuit breakers to be sure. Then start turning things on one by one until the culprit is identified (this is ideally done on the ground, if the problem can be replicated there).
Another possibility to consider, and is harder to diagnose, is internal cross-talk in the GTN unit, e.g. from the GPS circuitry to the comm/nav radios, etc.

 

[Marauder]

My guess regarding specific discrete frequencies that have a constant "open squelch" problem is that there is external interference injecting noise into the channel and causing that. I think this is unrelated to "squelch tail", which would affect pretty much all channels.

That interference could be emanating from anything electronic on board, with one suspect being the alternator/regulator. What I would do (and have done in the past) in such cases, is to turn off everything but the problem radio (e.g. turn off the alternator field), and pull all available circuit breakers to be sure. Then start turning things on one by one until the culprit is identified (this is ideally done on the ground, if the problem can be replicated there).

Another possibility to consider, and is harder to diagnose, is internal cross-talk in the GTN unit, e.g. from the GPS circuitry to the comm/nav radios, etc.

Thanks for the suggestions. The shop I am working with already removed the second NavCom (a Narco) to see if there was interference coming from it (it wasn't).

Will start unloading the electrical system to see what that does.


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[RotorDude]

Thanks for the suggestions. The shop I am working with already removed the second NavCom (a Narco) to see if there was interference coming from it (it wasn't).

Will start unloading the electrical system to see what that does.

OK, please keep us posted.

 

[Marauder]

OK, please keep us posted.

Update: I have figured out what is causing the GTN 650 to open the squelch. Now I need to figure out how to make it stop.

I installed a JPI 900 to replace a 830 just before the issue started. Since it was only certain frequencies, I never made the connection. The problem is reproducible (pull the JPI breaker and it closes the squelch). Anyone have any idea why a JPI 900 would cause an issue and the 830 didn't? Other than an ammeter shunt and fuel tank readings, all of the other features were on the 830.


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[Henning]

Perhaps it's a difference in the LCD drivers? Maybe the antenna cable got re-routed or had a noisy wire from the ammeter shunt tied to it?

 

[Marauder]

This video will show what is causing the Garmin GTN to open squelch. Waiting for JPI to provide a solution. https://youtu.be/C_I-OjGJI-U


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[RotorDude]

This video will show what is causing the Garmin GTN to open squelch. Waiting for JPI to provide a solution. https://youtu.be/C_I-OjGJI-U

Cool! Hopefully they'll find the culprit and fix it very soon. Seeing it in the handheld is impressive, since it means it's not a directly wired ground or power connection.

 

[Marauder]

Cool! Hopefully they'll find the culprit and fix it very soon. Seeing it in the handheld is impressive, since it means it's not a directly wired ground or power connection.

It was a strange one. Even JPI tech support told me they needed to consult with their R&D folks to understand why it is occurring. Good to know what is causing it...


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[mr ed]

Not a Garmin issue but jpi. Jpi box internals is ge!nerating rf interference which leaks out via the wire. Quick Fix is to put a filter on the sensor wire. Proper fix is for jpi to 1) better test their hw and 2) put a low pass filter internally on the outputs which is a hw mod.

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[Marauder]

Not a Garmin issue but jpi. Jpi box internals is ge!nerating rf interference which leaks out via the wire. Quick Fix is to put a filter on the sensor wire.

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That's exactly what JPI is having me do. They are setting me a filter for the indicator wire.


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[Comanche flyer]

Thanks for starting this thread. Since it is dedicated to the GTNs are any of you experiencing open squelch issues on some freqs?


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I got lot of RX noise like receiving some times, my gnc on same freq doesn't pic the RX noise.
Not a big deal tough is very rare and I think is due to moving away from transmitting stations.

 

[RotorDude]

Garmin has just issued their Service Bulletin for the release of new software version 6.11 for the GTN 6XX/7XX.
The most important new feature IMO is the user friendly arbitrary hold-at-any-fix capability.
Another interesting feature is the addition of LP+V (advisory glide slope for LP approaches). (I was somehow under the impression they were already there, but apparently not.)

 

[drotto]

Last few times I have flown, I have notice a feedback type interference. Adjusting the squelch does not seem to make a difference. Using a Bose A20 headset, will the new firmware make a difference?

 

[Jim Rosenow]

Ran across our avionics guy today. He said Garmin just came out with a new 650/750 firmware update yesterday or the day before.... fwiw.

Jim

 

[tsts4]

Just found out that for the first time Garmin is going to make a system software update downloadable for self-install by us E-AB folks with this update. For those interested they will be pushing out SB 1613 which is the E-AB counterpart to SB 1580, the V6.11 firmware update for standard type certificate aircraft.

 

[RotorDude]

Just found out that at least one avionics shop has encountered problems installing new GTN version 6.11 (resulting in a bricked 750 ). So some pilots are going to wait a bit before working up enough courage to possibly disable their aircraft by inserting a microSD card...

 

[tsts4]

Just found out that at least one avionics shop has encountered problems installing new GTN version 6.11 (resulting in a bricked 750 ). So some pilots are going to wait a bit before working up enough courage to possibly disable their aircraft by inserting a microSD card...

I downloaded the update a few minutes ago and plan to do the update tomorrow. I'll report back with the results good or bad.

 

[tsts4]

Thanks for posting this. Maybe I will wait.

Having never been through a software update with an installed Garmin GPS, where can one find instructions on how to use the new features? I received two emails from Garmin which gave an overview of what the changes are, but not how to use them.

From the SB: The following documents have been updated to reflect the changes associated with GTN 6XX/7XX Series
Main Software version 6.11:
 GTN 650 Series Pilot’s Guide (Garmin P/N 190-01004-03) Rev K or later
 GTN 750 Series Pilot’s Guide (Garmin P/N 190-01007-03) Rev K or later
 GTN 650 Series Cockpit Reference Guide (Garmin P/N 190-01004-04) Rev J or later
 GTN 750 Series Cockpit Reference Guide (Garmin P/N 190-01007-04) Rev H or later

The latest Pilot’s Guides, Upgrade Supplements, and Cockpit Reference Guides can all be downloaded
from the Garmin website.

 

[RotorDude]

I downloaded the update a few minutes ago and plan to do the update tomorrow. I'll report back with the results good or bad.

If it hasn't crashed and bricked the GTN on you, you are probably good. In the incident I am aware of, it happened almost immediately, most likely due to some glitch in the data or the install process.

 

[RotorDude]

Thanks for posting this. Maybe I will wait.

Having never been through a software update with an installed Garmin GPS, where can one find instructions on how to use the new features? I received two emails from Garmin which gave an overview of what the changes are, but not how to use them.

I would recommend downloading the latest (free) Garmin GTN trainer version and playing around with it, since it's updated to version 6.11.

There is some decent information on the BruceAir blog, as well as others.

 

[tsts4]

OK...I give up. I can't find where to get the "free" GTN trainer. I see one for $25. I know I downloaded one last year for free.

Thanks for the BruceAir link, very helpful. The link for a "free" GTN 750 trainer in the BruceAir article is for a GTN 620

Did you look in the Apple App Store? Disclaimer: I don't have an iPad so haven't actually downloaded it myself so can't vouch if it's still free but I know it's in the store.

 

[RotorDude]

OK...I give up. I can't find where to get the "free" GTN trainer. I see one for $25. I know I downloaded one last year for free.

Thanks for the BruceAir link, very helpful. The link for a "free" GTN 750 trainer in the BruceAir article is for a GTN 620

Try the free GTN 620 (2GB!) here. I believe it has both the G500 and the GTN 750/650 inside it.
I downloaded it a couple of weeks ago, and it seems to run fine. It is much improved over their old version from 2011 or so. Please let us know here if it worked for you.

 

[Jim Rosenow]

Interesting piece of trivia for the flight simmers among us who also have real GTN's. 'Rumor' has it that it's possible to import the real-world data into one's sim GTN and run current charts, etc. I'm told...

Back to your regularly scheduled thread...

Jim

 

[RotorDude]

Interesting piece of trivia for the flight simmers among us who also have real GTN's. 'Rumor' has it that it's possible to import the real-world data into one's sim GTN and run current charts, etc. I'm told...

Back to your regularly scheduled thread...

Jim

That's less urgent now, since their latest version is pretty much up to date. It used to be a major issue before this version, when the approaches were woefully behind reality. It will presumably become important again in a few months or so.
It would sure be nice if they would just let us import the latest rev from the microSD.

 

[MooneyDriver78]

Did you look in the Apple App Store? Disclaimer: I don't have an iPad so haven't actually downloaded it myself so can't vouch if it's still free but I know it's in the store.

The PC, aka Windows version is free, no idea why iPad version isn't ?

 

[tsts4]

So just completed the update -- took all of about 10 minutes and that included writing down settings (eg ARINC 429 and RS-232 configs) in case there were any issues.

 

[Gucci Pilot]

Found out the Seminole I'm gonna be doing the ATP in has the 650, I got the GTN Trainer iPad app(I don't have Windows stuff) and have been playing around with it and watching video demonstrations on YouTube and Garmin. Coming from using the KLN 89B, 94, and Garmin 430 during almost all my training and GA flying and an early 90s series FMS in my professional flying, all I can say is...WOW...what a game changer. I was like, "How neat would that be if I tapped on a VOR on the map and it told me about it or tuned it in the NAV radio." Then I tapped on the VOR....Jaw dropped.

 

[petrolero]

Found out the Seminole I'm gonna be doing the ATP in has the 650, I got the GTN Trainer iPad app(I don't have Windows stuff) and have been playing around with it and watching video demonstrations on YouTube and Garmin. Coming from using the KLN 89B, 94, and Garmin 430 during almost all my training and GA flying and an early 90s series FMS in my professional flying, all I can say is...WOW...what a game changer. I was like, "How neat would that be if I tapped on a VOR on the map and it told me about it or tuned it in the NAV radio." Then I tapped on the VOR....Jaw dropped.

That was my reaction too. I had an Apollo GX60 coupled with an MX20 before and the difference between that and the GTN 750 was huge in terms of readability, intuitiveness, usability, customization, and speed of use.

How have you found it to work in turbulence? My experience has been that I'm obviously slower than in smooth air but still faster overall in turbulence now than I was programming the GX60 and MX20 in smooth air. I hated the GX60's interface going all the way back to my days in the CAP when they used them.