There is a way around this - Use a Chrysler MAP sensor.  It makes a
difference which one and I don't have the part number handy, but I can get
it if you like.  The sensor has a different pressure port, different
connector and a different mounting, but that's all small stuff for us
experimental types.  The Chrysler sensor has a different calibration curve,
but that doesn't seem to bother the S-TEC system at all.  It is much more
resistant to EMI and RFI and it will run on the 9 volts that the system
requires.  Most 5-volt devices won't do that.  I've been using one in my
Cessna for a few years with no problems.

Gary,

 

I wish I would have known that, It probably doesn't cost anywhere near the many hundreds of dollars for the new S-Tec sensor (in a metal case). The calibration curve can't matter much since a minute pressure change activates the pitch servo.  I don't have vertical speed managed by the A/P - That's up to me and what's left of my hand eye coordination.