----- Original Message -----
From: "John Cliff" <john@crixbinfield.freeserve.co.uk>
> I have bought loads of Mil-spec cabling from Aircraft Spruce. It is
strange
> stuff to work with. The insulation can be melted off with a soldering
iron,
> but it is much more difficult that ordinary PVC insulation. 22 AWG is
> amazingly thin, with thin insulation but is strong and retains the shape
it
> is bent into. I have bought 10 AWG for the main alternator cables and 4
AWG
> for the battery cables. It solders up nicely and the insulation doesn't
run
> back when you heat up the copper core.
Solder? Are you sure you should be using solder joins? Probably not.
Solder joints are too brittle and the vibration of the engine as well as
other forces on the joint, may cause it to fracture quite early on. You
should be using crimp on connectors.
> I plan to use screened cable for most of the connections to the rear, with
> the earth in the screen. That way the cabling for each device is kept
tidily
> together.
Do you mean for power leads? I'd recommend agains this if you do. The
insulation beterrn the inner core and outer core may have a very low melting
point and the slightest overload in the cable may cause this insulation to
melt and there's more chance of a short circuit on that type of cable than
there would be it 2 individual cables. Also a sharp bend in the cable may
cause a short (I've seen it).
> I also plan to make the whole panel easily removable by having multiway
> connectors for the following :
>
> battery, regulator and earth
> magneto cables
> firewall forward connections (sensors, CS prop, tacho)
> rear compartment connections
> audio panel connections
> antenna connections
The antenna connector should be straight into the back of the
radio/gps/what-ever. An additional connector (if that's what you are
saying) may cause all sorts of SWR problems.
> These are written like this as each line represents one connector (except
> antennas).
>
> I would be grateful if anyone has any comments, praise, criticism,
warnings
> in respect of any of these ideas.
I'm not an expert on avionics and haven't done any on my kit yet, but I know
I wouldn't do what I's pointed out above. Sorry not to have any good
comments...
> As is often the case, the first one is the most difficult. All things
being
> equal I may be offering my services to do electrics at some time in the
> future. Currently my offerings are restricted to conversion of standard
> headsets to ANR (Active Noise Reduction). I do this with a kit, replacing
> the 'Y' piece with the battery box, and inserting a 'turn the ANR off if
the
> mike bias voltage is zero' circuit which saves PP3 batteries. I have done
38
> conversions so far. If anyone is interested contact me again. The Europa
> will go one step further and will use XLR plugs (5 way - standard on a
777)
> for audio connections. One pin will have the 9v required for the ANR.
Presto
> - no battery box required.
Nice one, batteries are a pian in the butt!.
Cheers,
Mark.
________________________________
Mark Jackson - 07050 645590
europa-builder@ntlworld.com
http://harley.pcl.ox.ac.uk/~mark/Europa
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