Re: Noisy K3 Receiver

Posted by Julian, G4ILO on Dec 17, 2009; 11:31am
URL: http://elecraft.85.s1.nabble.com/Noisy-K-3-Receiver-tp4173832p4180780.html

A new noise has recently started appearing at this QTH on 10m, which was previously a quiet band. Normally the S meter would read about S2, but now it reads about S5. This noise, heard through the K3, has a distinct "buzzing" sound.

I decided to switch the antenna to the FT-817 in order to record the noise, because the 817 is connected to the default sound card that Windows Recorder will record from. On that radio the noise sounded completely different. The buzz was not audible at all, it was just a sort of "mush". Except for the increased level (the FT-817 S-meter was reading S8 with preamp on) you might think you were listening to band noise.

Now why would noise sound different on one radio to another? I'm sure the buzz is really there, coming from some new device a neighbour has acquired, and the K3 isn't making it up. So perhaps the K3 is reproducing the sound of the band as it really is, while the lesser receiver has a lot more intermodulation that is mixing up all the noise which just happens to make it sound less harsh and easier on the ears?

I find it hard to believe that the K3 receiver is actually noisy, in the sense that it is generating noise internally that makes it harder to hear weak signals compared to another RX. Those MDS figures can't lie, surely?

So why is a new DSP board needed, except to "fudge" the sound so that it doesn't sound as noisy? You aren't going to hear anything with the new board that you wouldn't have heard without it.