Having had both near midairs due to too much time looking at non-audio mechanical varios, and TE probe failures, I now have one of each. My SN10 uses a nice Ilec TE probe (pointed up, by the way ;^), and my backup is a Westerboer 1020 with electronic TE.

And yes, I have two separate redundant battery systems, which has never failed in over 14 years in the same glider...keep it simple and check often.

I also have a big hammer in my trailer (for tiedown stakes) ready to be used on any loose mechanical, non-audio varios...

Kirk
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