I haven't used my KX3 in a while and updated the firmware. In CW mode, I notice there is substantial receiver noise at low volume with headphones. The noise appears to be more active when a received CW signal is present. Also, activating the attenuator also increases the noise and distortion.
The received CW tone also seems to get tinny and distorted at minimum volume. ie - at zero volume, it is quiet, turn up just enough to start DSP hiss (AF-1). Turning up the volume tends to drown out the noise, but it is WAY to loud in my earbuds...I only need the lowest AF setting to hear just fine.
Try going into the menu and turning on the RX I/Q out. I noticed on my kx3 with the latest firmware, there is a sharp hum and audio distortion while the RX I/Q out is disabled. The noise is so piercing I can't use headphones with it. Turning on the RX I/Q instantly kills the unwanted receiver noise.
Have also taken up this on other KX3-forums with little or no response...
I think it has to do with the greater span of the volume that we got in one of the previous downloads. Not really noticible if not using earphones /plugs with good sensitivity.
My KX3 was always very quiet , the filter settings dictated the audio passband out to the phones/external amp and inbuilt speaker. Not so any more. First the slight distortion on CW as well as SSB and probably more annoying the added white "hiss" at certain volume settings that is clearly outside the set filter passband !
I would gladly trade some of the new expanded volume range for a more relaxed setting and NO added distortion or hiss.
Unfortunatly trying with the I/Q-settings did not helpe me with this issue.
Hopefully the next download will cure it. / Carl, SM6HYG.