Hour meter with electric tach

[PT20J]

According to the wiring diagram, the hour meter is fed from the electric tachometer on my M20J. Does anyone know how this works? Is there a cut-in rpm below which it doesn’t record, or does the tach pilse modulate to simulate the hour meter on a mechanical tach?

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[kortopates]

The latter.


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[PT20J]

5 hours ago, kortopates said:

The latter.
 

Thanks. Any idea what rpm it’s calibrated for?

[kortopates]

9 minutes ago, PT20J said:

Thanks. Any idea what rpm it’s calibrated for?

From memory, I recall ~2550 rpm.