Bob Harrison wrote:
> ....
> If I was to "do over" I would have completely separate circuit negative
> returns to the bus bars to any "ground" connections. In other words the "the
> grounding system" needs to be a separate system back to either the battery
> or the engine direct.
> ....
When it comes to EMI, "do over" can go with the territory, Bob! On
production A/C, they have gotten away with common airframe grounding,
even for mic audio, w/o shielded wires. But the jacks are grounded by
default anyway. I haven't been able to find whether a fiberglass
airframe is more of a problem, but here's what Lancair sez:
8. What wiring do I need shielded wiring for?
Typically shielded wiring is used for all audio wires between the
radios, any digital databus, serial interface, High power pulse
equipment, strobe light wiring (including A+), engine sensor wiring,
mag leads, stormscope cables, etc. Shielded wiring should be grounded
at one end only, usually the load end. Linear solid state voltage
regulator does not require shielded wiring. It does not hurt to shield
all wiring in the airplane if you are so inclined.
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Here's some more sites that tackle EMI:
http://avstop.com/maint/alterations/ch2.html
http://www.glenair.com/html/emi.htm
http://www.sacskyranch.com/ignoise.htm
Regards,
Fred F.
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