GTN 650 Xi receive sensitivity

[PT20J]

I'm still testing everything in my new panel. Recently, I noted the GTN 650 Xi com receiver breaking up on distant stations that the GNC 255 received clearly.

Reading the GNC 255 installation manual, I learned that the newer GNCs have a default squelch setting of 0 which sets the squelch opening at about -107 dBm. According to the GTN installation manual, the GTN 650 Xi has a default setting of 57 which equates to a squelch opening of about -98 dBm. To get the sensitivity on the GTN to equal that of the GNC requires the GTN to be set at about 10 (it's not linear).

I set the GTN squelch to 10 and now it's receive sensitivity is about the same as the GNC. So far, I'm not getting spurious squelch breaks with this setting. I'll report back if there are any issues. But it appears you can get better performance with the GTN 650 Xi by setting the squelch lower in configuration mode.

Skip

[EricJ]

18 hours ago, PT20J said:

I'm still testing everything in my new panel. Recently, I noted the GTN 650 Xi com receiver breaking up on distant stations that the GNC 255 received clearly.

Reading the GNC 255 installation manual, I learned that the newer GNCs have a default squelch setting of 0 which sets the squelch opening at about -107 dBm. According to the GTN installation manual, the GTN 650 Xi has a default setting of 57 which equates to a squelch opening of about -98 dBm. To get the sensitivity on the GTN to equal that of the GNC requires the GTN to be set at about 10 (it's not linear).

I set the GTN squelch to 10 and now it's receive sensitivity is about the same as the GNC. So far, I'm not getting spurious squelch breaks with this setting. I'll report back if there are any issues. But it appears you can get better performance with the GTN 650 Xi by setting the squelch lower in configuration mode.

Skip

9dB is a pretty big delta.   That should definitely be noticeable.

[ArtVandelay]

I lowered it to ~30 IIRC, it was originally set to something like 75.

[PT20J]

I was actually able to have the GTN squelch set to 0 without spurious squelch breaks. 

[Pinecone]

Does this have to be done by an Avionics shop? 

[jetdriven]

set it to basic and 0.   thats the only way it works evidently.

i got the XI and replaced a straight 750.  I flew home actuial IFr in the clouds as I was in a hurry. I missed a lot of radio calls.

[jetdriven]

i dont know why i had to pay 500$ installation to slide the XI into the GTN750 tray either.

[RoundTwo]

23 hours ago, jetdriven said:

i dont know why i had to pay 500$ installation to slide the XI into the GTN750 tray either.

Where?

[jetdriven]

A Garmin dealer In NC but they all do that