Paul (and others),
           I made a breakthrough this  weekend on the fuel probe
   problem.  I
           rewired the right probe with shielded wire from the probe all
       the way to
           the EFIS.  Power up the EFIS and Nav/Com, hit PTT, and the
   gauge is
           steady as a rock.  The left gauge (the one that I haven't
       changed) still
           acted up as always, but it will be next to fix.  But the right
       one with
           shielded wire appears to be working great.  It was too late in
       the day
           to fly it, but I feel 99% certain that this has corrected the
       problem.

           Thanks to everyone that shared their ideas and suggestions on
       how to fix
           this very annoying (and potentially dangerous) problem.

           Mark S.
           25.5 hrs

           Congratulations Mark. You had a real bear of a problem there for
       awhile.
           These kinds of problems usually require real expensive
   instruments
           to trouble shoot like field strength meters and VSWR meters.

           Probably a good plan of attack is shield everything in an
   airplane
           including all the engine computer wiring.
           --
           Paul Lamar ...No rotor no motor.


       Shielding power and (especially) ground will rarely provide value in
       most systems - especially those that burn any significant amount of
       power - RF noise like this is low energy only affecting low power
       devices like sensors..  There would be _no_ value in shielding
   any dc
       lighting circuit wiring (nav/landing, cabin, panel lights), and
   likely
       no value in shielding the power leads to radios or other avionics.

       Shielding low voltage signaling wires (sensors) where
   appropriate can be
       a good deal.

       Thanks to Mark for letting us know what the resolution was.


       Regards,

       Matt-

       That assumes people know what is what :) Electricity is a mystery to
       most:)

       Paul Lamar

   True.

   Get Bob Nuckolls' book "The Aeroelectric Connection."

   https://matronics.com/aeroelectric/Catalog/pub/pub.html

   If you _no_ electronics experience the book might seem pretty dense (but
   comprehensible).

   If you have any electronics experience, this book will fill in the
   relevant details when it comes to aircraft wiring.

   If you have any questions post them to the aeroelectric list (or here) -
   even if you don't have the book, and likely a good discussion will come
   about.

   Bob Nuckolls rubs some people the wrong way - because he is forever
   committed to understanding things via the simple ideas of physics.  He
   won't let people get away with irrational BS when it comes to design
   philosophy.  He also won't get into cookbook instructions (though he
   does provide some very useful wiring diagrams to start with), but
   instead thinks that everyone (that might be building an airplane) has
   the capability to understand the fundamentals well enough to make their
   own design and construction decisions.

   I find his approach and methods to be refreshing and the _right_ way to
   do things.



   Regards,

   Matt-

   Sounds like me :

   Paul Lamar


Well, sure.  :)


Matt-


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