What is This? Digital Modes on KX3

I have been having a blast lately with digital modes like PSK-31 and JT-65/JT-9.  My little KX3 is doing a great job even without having run the temperature compensation. Of course I am keeping my power to 2 or 3 watts – which helps a lot.

I have noticed a strange thing for a while, but I am just now getting around to asking about it.

When I look at the waterfall there is an area that is basically blanked out – for lack of a better term.

Here is a screen shot of the waterfall in WSJTX (JT-65).  You will notice the black area on the left.

Waterfall of WSJTX – What is “black” on left edge?

As you can see there is an area on the left that is in the frequency range, but it is “blacked out”.  I wonder how many signals are in this area?

Those if you with a KX3 or those of you that might know what this is – please let me know!  If you know how to fix this, please let me know that as well!

I am looking forward to hearing the responses – I appreciate the help!

Burke Jones, NØHYD, is a regular contributor to AmateurRadio.com and writes from Kansas, USA. Contact him at [email protected].

4 Responses to “What is This? Digital Modes on KX3”

  • Harry K7ZOV:

    The black area is where you bandpass filter does it cut off. The KX3 has a very good filter system as you can see. Just for yucks make you bandpass narrower. You black are will get bigger. I am glad you are have such good success with these modes. Have fun…

    73 Harry K7ZOV
    KX3 Serial #0064

  • jeff n1kdo:

    It looks like you have 3.1 KHz of bandwidth showing there, did you try adjusting the PBT bandwidth? The stuff all the way to the left (near 0 hz) is likely noise on your audio interface.

    Jeff n1kdo

  • Burke Jones N0HYD:

    Thanks guys! The PBT is opened all the way up since I am using Data A mode on the KX3. Forgive my ignorance, but could there be signals in that bandwidth that I am not seeing? Should I shift the scale over to move that further left?

  • Mike KG9DW:

    Yes there could be and probably are signals there. To check them out, move your center frequency (receive frequency) lower or higher to put the passband over them.

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