GI-275 interface to 300A Navomatic

[NordicDave]

Appreciate help from the brain trust.... I have a near new GNU-430W with a fully working Cessna 300A Navomatic autopilot.

I'm considering upgrading to a GI-275 and wondering if it can be integrated to this legacy AP? It's not listed on Garmin's interface list.

Having GPSS to drive this legacy AP would be a great interim step to later affording a GFC-500.

 

[CA182R]

The 300A relies on DG and TC. You could just replace the AI with a GI 275 ADI for now and not touch anything else. I did exactly this but with a G5 AI. That bought me some happiness and time to save more.

Later I think you could introduce the GI 275 HSI as a CDI replacement as a first next step. As second next step, replace the Navomatic with GFC 500 and remove the newly unnecessary flight instruments and vac pump.

 

[NordicDave]

The 300A relies on DG and TC. You could just replace the AI with a GI 275 ADI for now and not touch anything else. I did exactly this but with a G5 AI. That bought me some happiness and time to save more.

Later I think you could introduce the GI 275 HSI as a CDI replacement as a first next step. As second next step, replace the Navomatic with GFC 500 and remove the newly unnecessary flight instruments and vac pump.

This was the roadmap I'm hoping to achieve. Really like to get GPSS capability for my nicely working 300A A/P and later upgrade to CG-F500 A/P. It's an upfront cost issue for me that necessitates upgrading in stages. I'll likely go to a G3X and leverage the GI-275 as a back-up instrument.