EAA493 Mailing List: Transponder trouble

[Donald Treadwell (pilot.dt]

I switched to ADS-B early during the first rebate session in 2017. My Stratus 
ESB would not reset for a flight last Saturday. It was displaying 0273 from the 
last flight and there was no change when I pushed the VFR button.  I tried all 
of the numbers and only 0 and 4 would enter. I decided that 4400 was better 
than nothing. As I approached Mathis Field I contacted the tower at 10 miles 
and explained I was unable to change the squawk code. 
Today I looked up the transponder codes reserved online and discovered that 
4400 was reserved for SR-71 flights above FL 600. 
Don T.