Ian, Ken and Dave
Thanks for your comments confirming I'm not imagining hearing things!
Ive looked at the data line on the QLG3 and I see a short burst of data every second, but cant imagine that this is the source of what I'm hearing i.e. long periods of what appears to be a pure sine wave around 700Hz, I can also hear a similar pattern but much higher in frequency, 5000Hz maybe, in the background.
The fact that these signals cant be tuned by the VFO suggests to me that the signal is not being processed in the same way as receiving a signal off air, it seems like it is getting into a stage much later.
In Hans' recent YouTube video, he says that the receiver is not strictly a direct conversion as in the QCX, but has an IF of 12kHz implemented in the audio chain, achieved in the magic of the firmware. I wonder if the interfering signal is getting into the system at this stage.
I wonder if the QLG3 is generating signals internally in the range 0-48kHz which are getting into the audio system at the 12kHz IF frequency? I dont have a spectrum analyser, but would be interesting to see.
Ken, I wonder if you have only experienced this on the QMX/QMX+ ? you mentioned that you have experienced this? problem with the QLG1 and QLG2, both of which preceded the QMX.
Perhaps this is just a minor annoyance at the moment, but can see it becoming a significant problem as the firmware is developed.
Maybe the best solution is a toggle switch on the back panel to remove power from the QLG3 until its needed!?
73 Steve G4EDG
Steve G4EDG