[Elecraft] KX3 - sounds like filter "blow-by" - what am I hearing?

[David Feldman via Elecraft]

Another data point while testing -

If the BW is set to an even bandwidth (say 100, 200, 300, 400, 500 Hz) the blow-by effect is very pronounced
If the BW is set to an odd bandwidth (say 150, 250, 350, 450, 550 Hz) the blow-by effect is minimal or absent (not sure, but it is very minor.)

The FC setting doesn't seem to interact with this.

Thanks again any further advice!

Dave


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On Sat, Jun 27, 2015 8:01 PM MDT David Feldman wrote:

>
>I have been using a KX3 during FD, connected to some large (tower/yagi) antennas. Am operating CW exclusively. Although I've had the KX3 for a while, I've only used it casually until today's FD. All day I've been noticing (on 20 and 40M, with fairly strong signals - some ove S9 - across both bands) that I hear CW signals far outside the established CW passband (example setting FC 0.6 kHz and BP 0.3 kHz, I can clearly hear signals with beatnotes in 2-3 kHz range, including ability to copy callsigns.) Have observed this with preamp on or off (for these bands and antennas, I'd normally use preamp off) and attenuator on or off. In all cases I hear the unexpected signals; they are obviously much weaker than signals within the DSP passband, but they are quite audible with any of these (preamp/attenuator) settings, and unexpected as it seems the ultimate rejection of the DSP should be far greater than I'm observing (I've not encountered this effect since my
 old
> Galaxy V transceiver in 1972). 
>
>The KX3 is about 2 years old, firmware is up to date, it was built from a kit, has had no other problems, has no accessories (no roofing filter, no auto tuner, etc.), and seems to work normally otherwise.
>
>Would be grateful for any advice as to whether this is normal or abormal.
>
>Thanks,
>
>73 Dave WB0GAZ wb0gaz at yahoo.com
>