September 24, 2005

Today, Carl came around from USA Jet with an avionics test set. We ran the radio stack through it’s paces and watched what the EFIS 1 did. It behaved pretty well! It seemed a little too sensitive to the CDI outputs from the radio, so I need to check that.

The main reason for having him come over was to help troubleshoot the CDI needle for the GPS. Well, we discovered that the SL-30 was working as expected in digital mode. We needed to switch it to resolver mode in order to check the EFIS 1’s analogue inputs (which I wasn’t expecting to have to do) but that worked perfectly. So, CDI needle swings OK, and the Glideslope swings OK. They’re off the scale when Carl set half deflection, but that should be an easy fix. That means then that the EFIS is functioning correctly. My wiring from the ACU is correct. The NAV Valid Flag is working from the radio. Sweet. Now to figure out why it doesn’t do it with the GPS.

First I decided to try hooking up the GPS antenna to the GX-60 and wheel it outside. Ah ha! Now we have some valid Nav info, the CDI needle comes up! Perfect! I guess I should’ve tried this in the first place eh? Well, I’m happy today after all that. I wonder why it doesn’t swing the needles during the IFR test at start up?

So, the way I’ll be using my set up will be to have the serial interface as primary for the SL-30 to get the OBS functionality, radio frequency switching etc. and then have analogue as primary for the external GPS. If my serial connection goes awry during a flight sometime, I can switch the SL-30 to resolver mode quite easily and drive the EFIS with that. Perfect.