[paul330]

I am still building in my garage. I have just fitted my GNC255. Good news and bad news. It powers up OK and seems to talk to my Skyview using legacy SL30 settings. However, there is a loud background noise.

I have nothing else powered up and there is no noise on the intercom or my GNS430 when I power those up. Therefore I don't think it is a power or ground issue. The noise is there on both the COM and NAV monitor. If I turn the volume down low to below about 1/4, the noise goes away.

Could it be that I am in my garage and there is such a bad S/N ratio that the auto squelch can't cope? Am I worrying about nothing?

 

[Walt]

Are you sure you don't have the squelch open? Push the volume knob to open/close.

 

[paul330]

Wish I could solve all problems so quickly!

My first thought was a problem with the aerial so I disconnected and checked the continuity - 0 ohm on both signal and ground, so no problem. I then thought it might be something to do with the internal intercom (I have external GMA240) so I checked the settings and adjusted the internal squelch. Turned out that wasn't the problem but when I reconnected everything, the noise was gone! Must have not quite made the aerial on one of the BNC connectors. Not only that, but I could pick up some aircraft at our local airfield - loud and clear.

Noise is still there on the NAV monitor but NAV antenna not fitted yet so that makes sense.