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Garmin GNC 255 or TRIG 56/57 NAV/COM

I need to upgrade my current Bendix King KX155 to a suitable 8.33 KHz radio platform. This would be COM2, COM 1 being a GNS 530W. My avionics shop advises the TRIG 56/57 are finally available. I have drawn up a comparison list and both have the “essentials” but I would be interested to learn if anyone else has considered either of these equipment options or can offer some insight as to the better choice as I cannot locate any recent TRIG 56/57 related posts. There is an historic post relating to the need to subscribe to maintain the GNC 255 database and while you can enter your own in the TRIG you do of course have to ensure what you enter is 100% accurate (no idea what happens if you dial in a frequency to use that is not in the database). There is also a mention of importance of ease of channel spacing selection but is this still important today?

ETGR, United Kingdom

I did take into consideration to get a TX56, but abandoned the idea as it only offers NAV/VOR/ILS and support for CDI only – no GS – so it is not a 1:1 replacement for a KX155. If you want, and I did, have full redundancy on NAVCOM, you are indeed better off with a GNC255.

Germany

The TX56 does include standard glideslope output to a CDI so can replace a KX155 or SL30

TX56/56A and TX57/57A Installation Manual 5 April 2022. https://www.trig-avionics.com/library/01776-00-01%20AD%20TX56%20TX56A%20and%20TX57%20TX57A%20Installation%20Manual%20-%20June%202022.pdf

Nav CDI outputs
OBS resolver outputs
DME interface
Superflags Back course
ILS energise
Switched power
Issue AD
Conventional two wire C/H output to drive the external OBS.
King style Data/Clock/Request/Common interface to channel an external DME.
Nav and glideslope superflag outputs.
Annunciator output when Nav receiver is in localiser back-course mode.
Output active when an ILS is tuned.
Switched power output for nav indicator or other accessories.
Left/Right, To/From, Up/Down, and flag output

Last Edited by wigglyamp at 15 Aug 21:11
Avionics geek.
Somewhere remote in Devon, UK.

MichaLSA wrote:

TX56, but abandoned the idea as it only offers NAV/VOR/ILS and support for CDI only – no GS

Then why does it have a “Built in 40 channel glideslope receiver”…? (See https://www.trig-avionics.com/product/stack-nav-com/)

ESKC (Uppsala/Sundbro), Sweden

I was only referring to the time I was into the evaluation. It appears the long time from announcement to availability is partly due to extended functionality.

Germany

I would buy anything other than Garmin if it’s reasonable to do so. Buying from Garmin is like a game of chess in which their objective is to gain your commitment before you realize that they have found a way to extract more money from you now, or over time, or when planned obsolescence kicks in.

Last Edited by Silvaire at 16 Aug 16:12

Thank you all for your comments; very much appreciated. The Garmin does require a subscription of $25 per year for the comms database. My GNS 530W failed during IR(R) ILS training at Southend while on 05 base leg, an event which turned into a useful secondary training exercise! I am therefore rather drawn to the benefits of a solid embedded database rather than something I have to input (with potential for errors and of course time) as with the TRIG 56/57. I will read through both user guides and make a decision subject to delivery time. While the panel is open I will also have the workshop install a Flight Stream 210 which will of course means deciding Garmin Pilot or Foreflight given I now use Sky Demon.

ETGR, United Kingdom

Steven_P wrote:

I am therefore rather drawn to the benefits of a solid embedded database rather than something I have to input (with potential for errors and of course time) as with the TRIG 56/57.

You don’t need to enter them manually, they can be uploaded in CSV format from a USB drive. Unfortunately, TX56’s memory is limited to 200 COM and 200 NAV stations, so you may have to upload a different set of stations when flying far away from the home base.

LKBU (near Prague), Czech Republic

Apologies – poor terminology on my part. Yes you are correct however I presumed the data required has to be entered into the spreadsheet to create the CSV file for upload – hence “manual entry” or is there some means by which the frequencies and presumably station identifiers can be readily obtained in CSV format?

ETGR, United Kingdom

What I don’t like on the GNC255 is that you need to push the C/N button to see the NAV frequency it adds up to the workload during an instrument approach. Unless you have glass panel where you can see the LOC frequency remotely. I chose to replace my 165 with a 165-8.33. Trig doesn’t have this issue all frequencies are visible……Also the King has better audio quality then the Garmin unit (this is a subjective statement of course). Don’t know about the Trig..?

EBST
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