I previously posted my plans claiming $1100 cost. So here's the follow up:
1. I did not count the cost of equipment already owned! This includes GRT HX, Garmin 420W, GTX-327 transponder, SkyRadar D ADSB-in. I didn't count my time, nor the cost of gas.
2. I bought the special Trig TT-22 mode S-ES transponder from GRT (modified to use the HX as the control head).
3. I paid a shop $80 to upgrade the 400W software to get ADSB+ output
4. I sold the GTX-327 ($600)
5. Today I qualified for the FAA rebate ($500).
What I learned:
1. You need to call or email GRT and get a beta software version for the HX (or other box, HXr, etc). You want to NOT have any built-in delays in switching from air to ground mode.
2. On landing, promptly brake to below 30 kias to get the transponder to promptly switch. Initially I was letting it roll down the long runway at a higher speed, and failing the "air on ground" test.
3. Make sure you do the 30 minute test flight in "rule" airspace (airspace where ADSB-out will be required in 2020).
If you have similar equipment, this is a pretty cost-effective way of complying with the 2020 mandate. If you have an HX, HXr, etc. but do not have an approved gps position source, GRT has promised one "soon" for $500 - but as of today, not yet available.
PS The Skyradar D (which I bought factory refurbished for $500) works great, displays on both the HX and on the iPad (WiFi to either Skyradar software, or WingX).Antennas are mounted inside, on the fiberglass doorposts in the -10.
1. I did not count the cost of equipment already owned! This includes GRT HX, Garmin 420W, GTX-327 transponder, SkyRadar D ADSB-in. I didn't count my time, nor the cost of gas.
2. I bought the special Trig TT-22 mode S-ES transponder from GRT (modified to use the HX as the control head).
3. I paid a shop $80 to upgrade the 400W software to get ADSB+ output
4. I sold the GTX-327 ($600)
5. Today I qualified for the FAA rebate ($500).
What I learned:
1. You need to call or email GRT and get a beta software version for the HX (or other box, HXr, etc). You want to NOT have any built-in delays in switching from air to ground mode.
2. On landing, promptly brake to below 30 kias to get the transponder to promptly switch. Initially I was letting it roll down the long runway at a higher speed, and failing the "air on ground" test.
3. Make sure you do the 30 minute test flight in "rule" airspace (airspace where ADSB-out will be required in 2020).
If you have similar equipment, this is a pretty cost-effective way of complying with the 2020 mandate. If you have an HX, HXr, etc. but do not have an approved gps position source, GRT has promised one "soon" for $500 - but as of today, not yet available.
PS The Skyradar D (which I bought factory refurbished for $500) works great, displays on both the HX and on the iPad (WiFi to either Skyradar software, or WingX).Antennas are mounted inside, on the fiberglass doorposts in the -10.
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Can you please provide some details around how you were able to register with the above equipment? That is fantastic news. 
