P-lead material

[Jr.CubBuilder]

Ok I have a newbie to plane maintenance question here. Where do you get new wire for P-leads and what should it be?

My old P-leads have a mesh around them for RF insulation I assume, but they are looking really ratty and they also look like something somebody put together after a few to many beers. They work fine, but I'd like to reroute them and the insulation is so old I think it's about to crumble. Any suggestions?

[GAHorn]

Use 18 ga shielded wire (MIL-C-27500 ) with ring-terminals at the ends. About $1/ft from Aircraft Spruce 877-477-7823, Ground the shield at the magneto end only.


http://aircraftspruce.com/catalog/elpag ... ldwire.php
and
http://aircraftspruce.com/catalog/elpag ... lterms.php

[Jr.CubBuilder]

Thanks George.

Do you have any suggestions for reading on some of this stuff? I'm not a complete novice, but I would like to find some books that might be good reference and learning tools.
Like for example, why ground only at the magneto end? I'm pretty sure mine are grounded at both.

[davevramp]

If you have one end grounded it acts like an antenna and grounds all spikes If you ground both it is a transformer and there will be a current flow and there will be reflected resistance in the p lead ckt and could change the coil out put in theory.
Only ground one side

[GAHorn]

Thanks George.

Do you have any suggestions for reading on some of this stuff? I'm not a complete novice, but I would like to find some books that might be good reference and learning tools.
Like for example, why ground only at the magneto end? I'm pretty sure mine are grounded at both.

Do you have the Cessna 170 Electrical Systems Service Manual? Available from TIC170A headquarters@cessna170.org