[Elecraft] K3 deaf when narrow filter engaged

[Andrew Moore]

New K3 with 3 filters:

FL1 - empty
FL2 - 2700 Hz
FL3 - empty
FL4 - 400 Hz
FL5 - 200 Hz

FL2,4,5 enabled, offsets and bandwidths entered, and filters plugged into
right slots (FL1 can remain empty right?)

When I turn the bandwidth encoder CCW, everything's fine until I hit 400 Hz.
 At 450, I hear signal. At 400, when FL4 kicks in, receiver goes quiet from
then on.

Ideas?

Also - RF calibration - I'm using an XG2 to feed the K3 a 50 uV signal.  The
K3 hears it at about S5 max, not even close to S9.  Followed the calibration
instructions.

--Andrew, NV1B
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