[prkaye]

I'm going to be removing my vans Tach transducer and wiring the Dynon D-180 tach transducer to the P-Lead of my left mag (using the resistor as instructed).
The Dynon installation manual (page 3-4) shows this being wired through the ignition switch, i.e. dynon rpm input -> resistor -> ignition switch -> P-lead.
Why? Can't I just go dynon rpm input -> resistor -> P-lead , without wiring this through the ignition switch?

 

[az_gila]

Distance

You can, but it's usually a shorter wiring path to pick up the P-lead signal off the back of the ignition switch...

 

[prkaye]

Really? The signal still has to get all the way from the mag (where it is generated) to the RPM-left input of the Dynon. Seems to me that the total wire distance would be longer by going through the switch... The wire has to go to the switch, and then out to the P-lead. By going direct to the P-lead, it would be a shorter total wire distance from the PRM left input to the p-lead. Plus I can then put the resistor much closer to the mag (instead of behind the switch).

 

[Bill_H]

It's not the distance, it's the ease. Avoiding making another firewall penetration or putting another wire through an existing one and resealing.

 

[prkaye]

It's not the distance, it's the ease. Avoiding making another firewall penetration or putting another wire through an existing one and resealing.

Ah, ok. Not an issue for me, as I already have the wire FWF to the Vans Tach transducer.

 

[az_gila]

You can, but it's usually a shorter wiring path to pick up the P-lead signal off the back of the ignition switch...

As noted earlier... it's usually a shorter distance for the added Dynon wire...

Need more coffee...