Receiver

AGC and Headphone volume
I use a Heil ProSet.  To avoid blasting my eardrums when I tune across a strong signal, I need to keep AF gain at 9 o'clock (no higher).  To provide
adequate amplification of weak signals, I set AGC THR to 8 and to give a little dynamic range between signal strengths, I set AGC SLP to 8 except 
during contests when I set AGC SLP to 3 to maximize the dynamic range for pileup readability. 

EQ Settings - Rag Chewing  
Below is the receive audio passband spectra at 2.8Khz and 3.2Khz width using the 2.8Khz and 6.0Khz 8-pole filters.  With the lowend extension 
added in firmware version 1.87, the receive passband is now flat down to 100hz with the RX EQ shown.  For SSB, the Shift control was adjusted for FC=1.45, 
which is the maximum shift toward the low frequency that has any true audible effect.  This has now changed with the extended low freq response of version 
3.33 firmware - use FC=1.35 for SSB.  The receive passband is now flat down to 50hz with EQ (see plot below) on an unmodified K3.  For AM, the Shift 
control is set to FC=1.65

Menu
Function
RX EQ
(SSB)
RX EQ
(SSB v3.33)
RX EQ
(AM)
TX EQ
(Ragchewing Heil HC5)
TX EQ
(Ragchewing Pro audio line in)
TX EQ
ESSB
EQ 1
50hz
0
+16
0
0
0
0
EQ 2
100hz
+8
+6
+8/+4
0
0
+16
EQ 3
200hz
+2
+2
0
+5
+2
+6
EQ 4
400hz
-1
0
0
+2
0
+3
EQ 5
800hz
0
0
0
-5
0
+1
EQ 6
1600hz
-1
0
0
-8
0
0
EQ 7
2400hz
-1
0
0
-8
0
-1
EQ 8
3200hz
-3
0
+1
-2
0
0







Elecraft K3 SSB Receive Passband: yellow is 2.8Khz filter, aqua is 6.0Khz filter at 3.2Khz width (both with shift at FC=1.45Khz)
 
(the 60hz peak is a computer artifact and is inaudible)





New lowend K3 Receive Passband extension with version 3.33 (and later) firmware, with EQ as shown above



 
TX "Pro" audio setup:
Marshall MXL2003 condensor mic
Behringer MX 802A mixer 
Behringer VX2000 voice processor with expander off, Tube emulation (warm/cold, 1.9K, full bw), Opto compressor (fast, hard, -25dB, slow release, +9dB, med enhance), EQ/De-ess out 
Behringer PEQ2200 parametric EQ (210hz 2.5oct -15dB, 450hz .55oct -9dB)  


For contesting, RX EQ is flat.


 


RX EQ Settings - Pink Noise Rolloff  
Paul PD0PSB suggested a pink noise 3dB/octave rolloff in the rx audio spectrum would create smoother sound in a posting to the Elecraft reflector.  I tested the suggestion using 
various RX EQ settings to vary the onset and degree of the rolloff as follows:



Menu
Function
RX EQ
(200hz)
RX EQ
(350hz)
RX EQ
(500hz)
RX EQ
(1000hz)
RX EQ
(1000hz) v3.33


EQ 1
50hz
0
0
0
0
+16
EQ 2
100hz
+8
+8
+8
+8
+6
EQ 3
200hz
+2
+2
+2
+2
+2
EQ 4
400hz
-3
-1
0
-1
0
EQ 5
800hz
-5
-4
-3
-1
-1
EQ 6
1600hz
-10
-8
-5
-3
-3
EQ 7
2400hz
-16
-10
-7
-5
-5
EQ 8
3200hz
-16
-16
-10
-10
-10



To my ears, the 1000hz rolloff (last column above - yellow curve below) sounded best.  Here are the resulting audio spectra:
 



Elecraft K3 SSB Receive Passband with RX EQ settings shown immediately above. Red is flat passband, Yellow is 1000hz rolloff, Green is 500hz rolloff,

Magenta is 350hz rolloff, and Aqua is 200hz rolloff.  K3 is in USB mode with 6.0Khz roofing filter at 3.2Khz width FC=1.45Khz



 



Width Setting (SSB) 
The K3 receiver in ssb actually has a bandwidth about 100hz narrower than indicated on the display.  For example, 1.9Khz on the K3 is equivalent 
to 1.8Khz on other radios.

Shift Setting (SSB)
The Shift (center freq) value has to be shifted downward as you narrow the ssb selectivity to preserve good intelligibility. These values work well for me:

Width
Shift
2800
CF=1.45Khz
1900
CF=1.15Khz
1700
CF=1.05Khz
1500
CF=0.95Khz


For contesting, I use width 1600hz, CF=0.95Khz



AF Limiter 
An AF level limiter was introduced with firmware version 2.65 for use with AGC off.  I have it set to "23" and use it often.  It is amazing how quiet and natural
the receiver sounds with RF Gain reduced and AGC off.

VFO Tuning Rate 
VFO FST is set to 20 to make the fast tuning rate more useable

 CW: 1Khz/rev slow, 2Khz/rev fast: VFO CTS=100 VFO FST=20 VFO CRS=1.0

SSB: 2Khz/rev slow, 4Khz/rev fast: VFO CTS=200 VFO FST=20 VFO CRS=5.0   


Transmitter
 
TX EQ Settings 
see table above - these settings were determined by recording my actual transmit signal on a second receiver with a 6Khz passband
  
Mic Gain and Compression
To correctly adjust Mic Gain, turn compression off (CMP=0) and slowly increase MIC while speaking a steady "aaaaahhhhhh" - you want to reach the 5th bar of ALC 
and not have the 6th bar turn on.  After this is set, don't touch MIC.  I found that for ragchewing, I want compression off for smoothest audio.  For contesting,
I set CMP to 23.

TX ESSB   
Elecraft provides support for 3.0-4.0Khz transmit bandwidth via dsp filtering starting with firmware version 2.23.  Below is a plot of the measured transmit passband 
bandwidth with the K3 configured for 2.8Khz (aqua, non-ESSB), 3.0Khz (yellow, ESSB) and 4.0Khz (green, ESSB) transmission.  No TX compression was used.



TX EQ Off: Elecraft K3 SSB Transmit Passband at 2.8Khz (aqua), 3.0Khz (yellow, ESSB) and 4.0Khz (green, ESSB)
 






TX EQ On: Elecraft K3 SSB Transmit Passband at 3.0Khz (yellow, ESSB) and 4.0Khz (green, ESSB)