I posted a note the other day that was probably misinterpreted because of
some omissions I made.  Regarding the Vision monitoring system someone
posted:  "Every temperature sensor is affected during comm transmit - CHT,
EGT, OAT, CAT and OIL."  What I said about the Vision FUEL LEVEL probe was
that "there was no....EMI protection built into the circuitry."  I should
have said that as far as I could tell there were no EMI protection
components in the circuit of the probe itself.  I then extrapolated this
observation to the inputs for thermocouple leads, which are low level analog
signals rather than the high level digital signal from the fuel probe -
certainly not a valid thing to do.  Another lister said that he had never
had any problem with EMI with the Vision fuel level probes and that is what
I have heard elsewhere.  Protection against EMI is a complex matter and
designing the EMI protection in (as is apparently the case with the Vision
fuel level probes) rather than adding it on is always a more robust and
desirable approach.  I'm sure that the Vision system is the most commonly
used monitor in high-end Experimental aircraft for a reason.

Gary Casey