[Elecraft] K3 MCU 2.38 Software Bug?

[Don Nesbitt]

Basic Parameters:

K3/100 with KRX3 - MCU 2.38, FPF 00.02, DSP1 1.90, DSP2  1.90

Main Board:  FL2 = 2.8; FL3 = 2.1; FL4 = 400 Hz
Sub RX Board:  FL2 = 2.8; FL4 = 400 Hz

AM Rx Enabled for FL2 Main and FL2 Sub
AM Tx not Enabled

I do NOT have a 6.00 AM Filter but am listening to AM through my 2.8 roofing
filter - which sounds pretty good!

Action:  Set Mode to AM.  Displayed Mode changes to AM and displayed XFIL
changes to FL2 (which would be expected as I have a 2.8 in FL2 and it is
enabled for AM receive) with "High" showing 3.00 and "Low" showing 0.00.  BW
shows 6.00. FC shows 1.50.

Surprise Action - Possible "Bug"

Now Tap "XFIL" button.  Displayed XFIL stays on FL2 - but - bandwidth gets
very narrow.  "High" now shows 2.20 and "Low" shows 0.80.  FC still shows
1.50 and BW now shows 2.8. But, the graphic display of bandwidth narrows to
what would be shown if I had BW set to 400 Hz and the recovered AM audio
sounds like it!  The BW showing 400 Hz is as it should be since 2.20 - 0.80
is 400 Hz.

Press and release "NORM" and I am back to where I started with Rx as it
should.  Even if I "Normalize" I and II so all is well and then do the "tap"
the "narrowing" scenario repeats!

What I've Tried:

I've downloaded and sent "All Firmware to K3" twice with the same result.

I've used the K3 Utility Version 1.1.6.3 to verify the filter settings that
I made in the Config Menu.

I've used the K3 Utility to set the filters and verified them in the Config
Menu.

I don't know if this action occurred in previous versions as I've stayed up
with all Beta releases but frankly never tapped the XFIL button before while
listening to AM.

Questions:

Can anyone duplicate this seemingly strange action when in AM mode and
tapping the "XFIL" button?

If it can't be duplicated, any idea(s) what I've got set incorrectly?

Is this simply a consequence of not having the 6 kHz AM filter and listening
to AM with the 2.8?

Thanks in advance.  '73 es gud dxing -- Don N4HH K3/100/KRX3 #83