Hum in the intercom

Darin Watson

Well Known Member

Friend

• Mar 24, 2023

• #1

I have been noticing a slight hum in the intercom shortly after start up when the alternator is putting out high amperage, and once the battery is topped off the hum fades.

Is it likely the engine to airframe ground strap?

 

J

JLuckey

Member

• Mar 24, 2023

• #2

Does the hum vary in frequency with engine RPM?

 

A

Avanza

Well Known Member

• Mar 24, 2023

• #3

The alternator is producing AC Voltage and Current.
It has a built in AC to DC rectifier.
When the load on the alternator is high it will produce more ripple, that is
small deviations from 100% DC. Try with a capacitor.

https://www.aircraftspruce.com/pages/el/voltagecontrols_capacitors/1105724.php

Good luck

 

WA85

Well Known Member

• Mar 24, 2023

• #4

I recently had something similar to this, turned to be a the bridge rectifier was going bad.

If you have a Plane Power alternator, you can replace the bridge rectifier with a OTC p/n INR724 bridge rectifier.

Cost was $55.00.