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Well, I've tried the internet and various homebuilder books but am still not 100% convinced of the correct methods for wiring a comms system into a wooden airframe.
The comms box (VALCOM 760 channel, tray mounted) works just fine until the fuel pump comes on. Now, I screwed up first time round by not using shielded Tefzel wiring since the original glider fitment used automotive grade PVC wires. I also didn't have a separate bus bar for the comms.
I now have a stock of shielded wire but am a little uncertain as to which wires need shielding and which ends need to be earthed.
1. Mic and phones. I believe that they need to be shieded and then only 'grounded' through the shielding on the 'radio' end. Is that right?
2. PTT. Some websites suggest the PTT also needs the same treatment as above whilst others say not. Which is it?
3. Can such wires be grounded to the chassis of the radio tray?
4. I use the ubiquitous Facet "Cube shape" pump which has a metal casing and unshielded wires. Is it worth trying a shield made from braid and slipping it over the wires? If so, do I ground it at one or at two ends?
5. I use a VW conversion with dual electronic ignition (Leburg) that uses carbon leads. Should they also be shielded or is the 10K ohms enough to dampen out the RFI?
Lastly, is there anone in the UK that I could call upon (e-mail or phone) with any other avionics questions?
Thanks, guys.
Rob ( and G-BMMF)
Light Aircraft Association : G-BMMF