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

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