Sound of a bottle of soda fizzling when not fully closed?

[Limeybastard]

I had my radio on with volume at min, so no audio is being output, busy messing around on my other desk with the PC hadnt been using the radio for over 30 mins prior. In the background I hear a faint fizzling bubbling gurgling type sound, almost exactly like a bottle of soda leaking air from a not fully closed cap.

I turn towards my radio, and put my ear against it, lo and behold its coming from there. LOL, Been hearing it for a while but never knew where it was coming from until lately. What is that all about?

 

[nomadradio]

Hmmm. I hear a funny sound coming from under the hood of my car.

But I won't tell you what brand it is, what model, or engine or how many decades old it is.

Can you explain what's causing this noise?

Okay, smart-a$$ed stuff aside, I would blame a failing electrolytic capacitor, maybe in the power supply if it's a switchmode type. Or maybe in the audio-preamp/volume control section? If it's a Cobra 2000GTL it may be time to re-cap the clock/counter module. There are ten or eleven small electrolytics in that module. When they fail, wacky noises will leak into the receiver audio.

One thing I have learned to try first with low-level audio noises is to turn the squelch control and see if that makes the sound go away. That would serve to pin down how far 'downstream' in the audio path the noise comes from. If the squelch quiets the noise, the source is upstream from the circuit where the squelch circuit shuts down the receiver audio. And if turning the squelch knob has no effect, the source would be downstream from that point.

73

 

[Limeybastard]

The sound intermittently emmits from the actual radio insides , independent of volume or squelch , it's so faint that it won't be heard if the speaker volume was is set at a bare minimum.

Like i mentioned, the radio was on volume down all the way, hadn't been TX ing on it either. The noise starts randomly and intermittently, When i first heard it a few weeks back though it was the PSU, but it wasnt.The rig is setup inside home.

Was just wondering what stuff would cause noises randomly inside a radio, lol