[Elecraft] K3 Beta Release: APF for CW; "Fast Monitor" & improved TX gate for voice modes

[Wayne Burdick]

K3 beta-test firmware revision 4.17 (with DSP rev. 2.65) is now  
available. This release includes our new APF (audio peaking filter)  
for CW mode, which has been helping K3 field testers work "extreme"  
weak DX for the past several days.

For voice modes, there's a "Fast Monitor" option (TX voice monitor  
without the processing delay). Also included is a much-improved TX  
Noise Gate.

See detailed release notes below.

Please send any questions to k3support at elecraft.com. For instructions  
on how to load beta firmware, see:

      http://www.elecraft.com/K3/k3_software.htm

73,
Wayne
N6KR

* * *

MCU 4.17 / DSP 2.65 / FPF 1.14, 11-2-2010

NOTE: Be sure to install all firmware files for this release,
including FPF 1.14. Otherwise your menu text will be incorrect.

* APF (AUDIO PEAKING FILTER) ADDED: APF provides enhanced
copy of weak signals in CW mode, and is especially useful when
signals are at the noise level. The K3’s APF is patterned after
the most successful analog APF implementations, and is equally
effective in user tests. To use APF, make sure CONFIG:DUAL PB
is set to APF. (This is the default. “NOR” restores the original DUAL PB
function.) Then hold DUAL PB to turn APF on/off. A special DSP
graphic display is used to show that APF is in effect. At the time
APF is activated, the regular I.F. SHIFT setting, if any, is “frozen,”
and SHIFT then controls the center pitch of the APF filter in 10-Hz
steps. APF is independent for the main and sub receivers, as well
as for presets I and II. Switching between these two presets is a
convenient way of turning APF on/off quickly.

* ADDED VOICE TX “FAST MONITOR”: Normally the voice
monitor includes a ~20-ms delay, which is necessary to hear how your
on-air signal will sound (with compression, etc.). If you prefer to not
hear any delay in the voice monitor, set CONFIG:TX MON to FAST.
Note: You’ll still hear the delayed and processed monitor if you
adjust the MIC, CMP, TX EQ or TX GATE settings while transmitting.

* TX NOISE GATE IMPROVEMENT: The Noise Gate/Downward
Expander for voice modes has smoother response and much
improved performance near the threshold.

* NARROW AF FILTER IMPROVEMENT: Adjusting SHIFT and
WIDTH when using very narrow DSP filters no longer causes
‘pop’ artifacts.