I was using an iPaq hx2410. In the heat, the screen would constantly
flicker and it looked like an old TV with the vertical hold out of
whack. Totally unreadable and unusuable, but it did keep recording
the igc file.

I now run a Navigon 2120 Max, works nicely. Can't connect it to a
flight instrument, but I don't have one that can send the data,
anyway.