Anyone out there with experience with aircraft electrical installation might
know the answer to this one.
I have a 912 Europa, flying happily now thanks, and I'm currently working
through all the teething troubles you normally encounter in the first few
hours of use.
I have Flightcom 403D Intercom and Flightcom Eclipse voice activated headsets.
I can't get the mic. voice channel to de-activate at high revs (4500 +), due
'engine noise'. Except of course, it's not 'sound pressure' noise, because
it only happens on 'both' magnetos, not 'left' or 'right'. Naturally, I've
tried all 'squelch' positions, and increased/reduced the mic. gain.
I've decided it's 'induced' into the mike circuit, from the a/c ignition and
I was wondering if anyone else has had similar problems with this or related
equipment.
There IS shielding round the mic. circuit but it's not connected to the a/c
ground because the installation guide suggests you shouldn't.
Should I try additional noise supression round the magnetos, spark plug h/t
leads ?
Should I increase the shielding round the mic circuit ?
Should I ground the mic shielding ?
I'd be grateful for any suggestions, as this is the sort of problem which
can take months to isolate.
Regards,
Alan Stewart (BWFX). Daytime 01473-605304 Eve. 01245-264186 (Ans)
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