Garmin GNS 480 VOR very slow to identify and loud chatter when monitoring

stevenhmiller

stevenhmiller

Pre-takeoff checklist
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I brought my plane into the avionics shop to get the VFR certification done. After picking it up and underway, I noticed that when I tune the VOR on the GNS 480, it takes quite a while to identify. When I turn on the frequency monitoring, I hear the morse code in the background but there is a lot of loud chatter. Almost like the magnetos making the noise, but not sure. I never had this problem before.

Anyone with a 480 have this issue before, and if so, what did you do to fix it? Right now, bringing the plane back to the avionics shop is not an option.
 
Nope, both my 480 and the SL30 (which share the same VOR section) identify fine. Could be a grounding problem. Does the noise exist on your other VOR radio (if you have one)?

What the hell is a "VFR certification?"
 
flyingron said:
Nope, both my 480 and the SL30 (which share the same VOR section) identify fine. Could be a grounding problem. Does the noise exist on your other VOR radio (if you have one)?

What the hell is a "VFR certification?"
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The King 155 brings in the signal and works fine with the VOR, but that's just a plain nav unit. I like to use the 480 because it does the ident for me. I can't hear the morse code for anything, so rely on the 480 to ident it for me.

The avionics shop does an IFR cert and VFR cert. VFR just certifies the transponder and main altimeter. I'm not an IFR pilot, so just need the VFR cert.
 
The 480's VOR receiver isn't much more than your KX155 (other than some better digital control stuff like memories and the auto ID). Do by "working fine" do you mean that you can hear the ID without the noise on the KX155?

Ah, well that certainly is a non-standard way of phrasing it and testing things. There's no requirement for periodic inspection of the (main or otherwise) altimeter for VFR flight. The transponder is always required (IFR or VFR). For IFR you need the static system, your altimeter(s), and encoder(s) tested.

Still nine times out of ten noise in the system is a grounding issue. I'd look at the VOR antenna leads particularly.
 
Ugh. Hate to go ripping the plane apart. Well, gotta do what needs to be done. I need to fix this.
 
stevenhmiller said:
Ugh. Hate to go ripping the plane apart. Well, gotta do what needs to be done. I need to fix this.
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Start simple. Your original post said it sounded like a magneto noise. Does it vary with rpm change? Does it vary when you switch one then another off?

-Skip
 
He still hasn't answered if it is present it BOTH VOR receiver's audio (or any other radio audio to any extent, you may have to hit the SQ button on the 480 or pull the volume control on the KX-155 COM to check this if it isn't breaking squelch). Does it still appear when the engine is off? As Skip suggests, does it vary with R/L mag?

There's a far cry from "ripping the plane apart" to diagnose this.
 
Skip Miller said:
Start simple. Your original post said it sounded like a magneto noise. Does it vary with rpm change? Does it vary when you switch one then another off?

-Skip
Click to expand...

True. Only heard it at cruise speed. Will take a listen this weekend while on the ground and play.
 
flyingron said:
He still hasn't answered if it is present it BOTH VOR receiver's audio (or any other radio audio to any extent, you may have to hit the SQ button on the 480 or pull the volume control on the KX-155 COM to check this if it isn't breaking squelch). Does it still appear when the engine is off? As Skip suggests, does it vary with R/L mag?

There's a far cry from "ripping the plane apart" to diagnose this.
Click to expand...

I haven't been up since Tuesday, when I first noticed this. I'll play with it this weekend, weather permitting.
 
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