[Elecraft] KX3 Beta firmware rev 1.57: ATU tuning and RX improvements

[Wayne Burdick]

KX3 beta firmware rev 1.57 (with DSP rev 1.22) is now available. This revision has improved ATU tuning, better SSB RX characteristics at narrow filter bandwidths, and eliminates a weak 12-kHz audio spur heard by some operators.

You'll need the KX3 Utility application to download and install firmware. For full instructions on loading beta releases, refer to our KX3 software page:

 http://www.elecraft.com/KX3/KX3_software.htm

73,

Wayne
N6KR

* * *

MCU 1.57 / DSP 1.22, 8-17-2013

* 12-kHz AUDIO SPUR ELIMINATED:  Some operators reported hearing a very weak 12-kHz tone at the headphone jack, even with the volume turned all the way down. This tone has now been suppressed by an additional 20 dB (approx.). 

* “WEAVER MODE” SSB RECEIVE IMPROVED:  When the high end of the KX3’s SSB receive passband is set below about 2.4 kHz using the PBT control, the DSP switches to “Weaver” demodulation mode. This allows roofing filter FL2 to be used. In previous releases, Weaver demodulation had poor opposite-sideband image rejection; this has been corrected. Note: It is not necessary to re-do RXSBNUL calibration.

* ATU IMPROVEMENTS:  Tapping ATU TUNE now recalls stored LC settings for the current VFO frequency prior to tuning, avoiding auto-tuning from scratch in most cases. Also, ATU settings are now reloaded (if necessary) when the A/B, A>B, REV, FREQ ENT, or SPLIT switches are used. This increases the likelihood that the ATU will be kept tuned during receive, improving sensitivity, without having to transmit first. Previously, only XMIT, TUNE and band changes would force an ATU settings reload.

Note: If you switch to a different antenna, such as when taking the KX3 into the field, you may want to clear old ATU LC settings for one or more bands prior to doing new auto-tunes. To do this, locate the ATU MD menu entry, then hold CLR (hold function of the OFS/B knob). You can change bands from within this menu entry using BAND +/-.