If there's no master switch and a bunch of fuses or circuit breakers, and you are blessed with turning off each instrument separately, then you'll need to locate the wire that provides power to those fuses (there may be a common wire going from one fuse to the next to provide power to each) that wire would be serving as the "buss". You'll need to locate the end that comes from the battery and insert the diode in series with that wire at the "first" fuse.

This is much more the situation I have. No master Avionic switch, just a master battery switch. I bet exactly what you are describing is mess of wires that I have not deciphered yet. Possible there may still be a buss completely buried under all the instruments in the bottom of the bird, but what you said above is probably it. Thanks so much,

Kevin
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