Hiss in the headphones in a Rotax-powered airplane
Moderator: drseti
Hiss in the headphones in a Rotax-powered airplane
I have recently noticed an annoying hiss in the headphones installed in my Rotax-powered plane. It is equally loud on both radios, but loudness seems to be rpm-dependent. and non-existent at idle power. There's no change in the "frequency" of the sound when RPM changes, only the volume. Anybody have any idea what's going on?
I agree, a bad ground is the usual cause, but it can also be a ground loop, where both ends of a shield ground are connected to ground when it should be just one end. I fly behind a Rotax and have never had a problem.
A side node/example. I just bought a new pickup. It has a jack to listen to my IPod, which is great, but when I set my IPod on the charger (in the cigarette lighter) there is a very annoying hiss. I'm sure it's a ground loop and this in a 2009, brand new vehicle. Without being in the charger it works great.
Ron
A side node/example. I just bought a new pickup. It has a jack to listen to my IPod, which is great, but when I set my IPod on the charger (in the cigarette lighter) there is a very annoying hiss. I'm sure it's a ground loop and this in a 2009, brand new vehicle. Without being in the charger it works great.
Ron
Hiss in the headphones
I think what I'm hearing is noise picked up by the mike - a David Clark electret - because when I wrap my hand around it the "hiss" goes away. It's as though the mike is picking up the sound of air rushing by the cockpit, a combination of propwash and slipstream air.
- CharlieTango
- Posts: 1000
- Joined: Sat Jun 10, 2006 10:04 am
- Location: Mammoth Lakes, California
Hiss in the headphones
Yeah, I've been thinking the very same thing. I'll check it out next time I fly.
-
- Posts: 81
- Joined: Sun Jan 27, 2008 3:18 pm
- Location: wisconsin
Hiss in the headphones
It was the squelch - squelch knob was turned all the way down.