Garmin GTN 750xi vhf issue

With the most comprehensive lineup of avionics upgrades in the industry, Garmin offers solutions for most any budget and mission.

Moderator: Moderators

fly1981
Taxiing to Clubhouse
Posts: 426
Joined: Wed Sep 26, 2007 5:54 pm
Closest Airfield: All over
Has liked: 1 time
Been liked: 9 times

Garmin GTN 750xi vhf issue

Unread post by fly1981 » Sat Mar 12, 2022 7:58 pm

We have just completed an avionics upgrade in our baron. The package included a garmin gtn750xi, which is used as com 1. I have noticed the range of vhf communications when using com 1 is shocking, in some instances 20 miles. Switch over to com 2 which is a 20 year old 430, and transmitting and receiving is crystal as clear. Any idea what could be causing this?
User avatar
Chalkie
Too Tousand
Too Tousand
Posts: 2032
Joined: Mon Jun 02, 2008 9:19 am
Closest Airfield: FAPX
Location: Jeffreys Bay
Has liked: 291 times
Been liked: 847 times

Re: Garmin GTN 750xi vhf issue

Unread post by Chalkie » Sun Mar 13, 2022 10:19 am

RF is a real black art/witches craft. I would take the aircraft back to the avionics shop and ask them to fix it.

However if you want to do your own fault finding, I would disconnect the coaxial RF cable at both ends and check for continuity and for a short circuit from centre core to shielding. It is quite easy when crimping the centre pin to the centre core of the coaxial, to misplace one strand and this strand could then short out the centre core to the shielding. This could result in the shielding becoming the RF radiator and not the antenna.

If coaxial is good, then try to swop Comm 1 and Comm 2 coaxial cables at the back of the radio trays, so as to have each use the other antenna. This way you can see if it is a transmitter problem or an antenna problem.

Have fun crawling under the panel...
Oh, Guru. Pray tell, what is the secret to happiness and contentment.
Never argue with an idiot.
Oh, but I disagree!
Yes; you are right.
fly1981
Taxiing to Clubhouse
Posts: 426
Joined: Wed Sep 26, 2007 5:54 pm
Closest Airfield: All over
Has liked: 1 time
Been liked: 9 times

Re: Garmin GTN 750xi vhf issue

Unread post by fly1981 » Wed Mar 16, 2022 8:15 pm

Thanks for the response Chalkie, I think it’s best I take it back to the shop that did the installation…

Return to “Garmin”