Static revisited

I have read thru some posts on headset static, most say to check the intercom plugs, grounding, try different headsets (I have tried two -- Dave Clark and a Stratus)etc...

We are close to 8 hrs on the airframe so far... I have noticed that at 3400-3500 RPM the static starts and does not go away until below that RPM. The Radio will TX/RX clear, but the static is constant in the background. I have talked to ATC and they had no complaints of any static coming thru. Same goes for the local UNICOM, other aircraft and handheld radios hear clear.

One post said it was the squelch? possible? The intercom works just fine too....just constant static at the higher RPM.

squelch

Are you saying that you can't squelch it out at a higher setting?

Grounding

I know you don't want to hear this but........check all your ground wires and plug grounding related to the radio and audio system.

KRAUSEGB said:

Are you saying that you can't squelch it out at a higher setting?

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Honestly, I have not yet tried the squelch yet.... That would be too obvious (haha).

I was thinking it to be a more "internal problem", such as the grounding; but everything is grounded per the plans ... and...i could be looking at it wrong, but would the static still be present even at low RPM's if the grounding was faulty??

Could you expand on the word "static"? White noise, whine, staccato pops, etc.? Does the noise change pitch with engine RPM? Does the level change when you change intercom volume settings?

BigJohn said:

Could you expand on the word "static"? White noise, whine, staccato pops, etc.? Does the noise change pitch with engine RPM? Does the level change when you change intercom volume settings?

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best descriptor would be white noise ... no pitch change per se, at the lower rpm setting below 3500, it fades out...yes volume of noise will go up and down with volume change on the actual headset volume control, garmin radio volume changes still work ok, just with the noise behind it (the noise does not increase or decrease with radio volume changes).

interesting note : ran the engine today, above 3500 on the ground, no noise....i did adjust the squelch knob on the intercom during the run-up. I may have to be in the air for the noise to occur, but i do remember it occuring (or did anyway) on the ground as well.

KALEWIS said:

best descriptor would be white noise ... no pitch change per se, at the lower rpm setting below 3500, it fades out...yes volume of noise will go up and down with volume change on the actual headset volume control, garmin radio volume changes still work ok, just with the noise behind it (the noise does not increase or decrease with radio volume changes).

interesting note : ran the engine today, above 3500 on the ground, no noise....i did adjust the squelch knob on the intercom during the run-up. I may have to be in the air for the noise to occur, but i do remember it occuring (or did anyway) on the ground as well.

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OK, that's good info to help isolate the source. Comments follow:

White noise, hiss, etc. indicates that it is not coming from the alternator.

Noise does not change with radio volume control - eliminates radio as source.

Noise changes with headset volume controls - doesn't help us to find source.

You didn't answer the question about whether the noise volume changes when the intercom volume control is moved. That is important because it will tell you if the noise is coming through the intercom, or from some other source.

My best guess with the info we have is that the ambient noise level in the cockpit is breaking the squelch when that noise level is at a high level during flight. And there is not enough noise on the ground to break squelch, hence no noise in headsets even during a runup.

Try the intercom volume test, and try adjusting the intercom squelch control in flight. Let us know how you make out.

I did not try the intercom volume, probably for the same reason I didn't try the squelch knob either .... Too obvious and being solo didn't think about it. If the weather holds out I will fly this afternoon and try squelching it out.

Thanks for the replies.

FIXED !!

Flew this evening, Adjusted the squelch and all is well. Thanks to all for the prompt replies