[Elecraft] K3S audio disappears with narrow filter selection

[John Shadle]

Hi,
I completed the build last night, and I am putting the rig through its
paces. I previously had a K3, so I am familiar with the menu and
configuration.

I configured the filters in the K3S as follows

FL1 - 6 kHz
FL2 - <empty>
FL3 - 2.7kHz (-0.95 offset)
FL4 - 700 Hz (+.04 offset)
FL5 - 400 Hz

I have tuned to a strong carrier (on CW) and then progressively narrowed my
bandwidth. When I hit FL5, the audio is strongly attenuated. It basically
disappears. I thought that something was wrong with my configuration, so I
checked it again. FL5 was set for 400 Hz, which the filter in FL5 is.

I performed several experiments. Choosing the filter with the XFIL button
does the same thing. Audio is present with FL3 (2.7kHz) and FL4 (700Hz),
but gone with FL5 (400Hz).

Then, I went into the firmware and changed the bandwidth of FL5 to a
narrower value (e.g. 250 Hz). I returned to listening to the audio and
using XFIL produced the same results as before; however, when I tuned down
from 700Hz to 400Hz, the audio was still there. When I went to 300Hz it was
still there -- but it disappeared at 250 Hz (as I had set the filter's
bandwidth in the firmware). Help!

There's gotta be something simple but critical I'm missing...somewhere.

Before you suggest it -- yes, I have tried to up the dB of the filter
compensation for FL5 (400Hz). I increased it to the highest value, and the
signal is still basically gone -- but maybe slightly higher.

-john NE4U