[Elecraft] K3 SHIFT / WIDTH oddity

[Joe Planisky]

Hey Folks,

I'm trying to determine whether an oddity I'm experiencing with the  
DSP filter is unique to my K3, or might be a general firmware bug.   
I'm using the beta 3.19 firmware, but have not tried it on earlier  
versions to see if it's unique to 3.19.

I have the 13 kHz, 2.7 kHz, and 400 Hz filters installed.

1. Go to a clear spot on any band (i.e. no signals, just noise). CW  
mode.

2. Set the "SHIFT" control to the minimum value (FC 0.15 on my rig).

3. Set the "WIDTH" control to BW 1.20.  Note the sound of the noise.

4. Rotate the "WIDTH" control CCW.  At BW 1.00, there's a drastic  
change in the noise.  The low frequencies disappear.

5. Continue rotating "WIDTH" CCW. At BW 0.85, the low frequencies re- 
appear and remain present through the minimum width (BW 0.05)

Here are (very rough) readings I took of the -6 dB points with  
Spectrogram:

BW    f lo  f hi
1.20  145   689
1.10  183   695
1.00  360   586
0.95  358   574
0.90  365   574
0.85  166   501
0.80  168   490
0.75  181   480

The shift on the low frequency end by nearly an octave between 1.0 and  
0.90 is clearly visible.  Note that throughout these readings, the  
XFIL display indicated FL2 (my 2.7 kHz) filter was being used.

If anyone else can reproduce this, please let me know.

73
--
Joe KB8AP