Elecraft K3S firmware v3.25

MCU 3.25 / DSP 2.21

New Features

• NOISE REDUCTION (NR) IMPROVEMENTS: Our new NR algorithm has less impact on signal strength, and should no longer make some weak signals ÒdisappearÓ due to over-processing.

We may fine-tune the algorithm in future releases, based on operator evaluation, but weve have good reports from early testers.

• VFO TUNING NOISE REDUCTION: Some operators have reported hearing noise on 60, 10, or 6 meters when tuning the VFO under very quiet conditions. If you experience this, try the following:

In the CONFIG: VCO MD menu entry, tap 1 until you see ÒSPI 2Ó (the default is ÒSPI 1Ó).

This alters the timing of data sent to the synthesizer, which in turn changes the spectrum of SPI-bus signal noise.

It has no impact on performance.

You will also need to add two resistors and two diodes to the bottom of the RF board (see application note on our K3 modifications web page).

• AUTOMATIC RECEIVER FRONT END PROTECTION: If the K3 is operated too close to high-power transmitters, its possible to damage some receiver components. While this rarely happens, weve taken steps to prevent it by sensing a high-current condition at the mixer post-amplifier (Q8/Q9) and automatically turning off the preamp and, if necessary, turning on the attenuator​. You will need to add one jumper wire on the bottom of the RF board (see application note on our K3 modifications web page). If you dont add the jumper, operation will be unchanged; firmware can sense whether or not youve installed the jumper.
• 10-HZ PASSBAND SHIFT STEPS (EXPERIMENTAL):

If CONFIG: PB CTRL is set to SHIFT=.01 for a given operating mode, the SHIFT control will provide .01 kHz (10 Hz) steps rather than the original .05 kHz (50 Hz).

Especially useful with narrow filter bandwidths.

This feature is experimental and has some limitations at present: Applies to CW and DATA only; LOCUT/HICUT cannot be used when 10-Hz SHIFT steps are in effect; WIDTH steps remain 50 Hz in all cases.

Not compatible with spur removal function yet (CONFIG: SIG RMV); signals mapped out may reappear.

• CW SPEED DISPLAYED WITH DECODED CW TEXT: If the TEXT DEC switch param​eter is set to WPM CHK (using VFO B), the speed of on-air CW signals will be shown, along with a small window of CW text.

You might see Ò18w. CQÉÓ, where Ò18w. Ó means 18 WPM. Both text decode and WPM display accuracy can be improved by using narrow filtering and by careful adjustment of the ÒTHRÓ (threshold) parameter (set with VFO A when the TEXT DEC switch is pressed).

• RF GAIN CALIBRATION: The K3s hardware AGC circuitry can now be calibrated. This may improve both S-meter and RF GAIN control accuracy.

To do RF GAIN calibration, use revision 1.2.7.24 or later of K3 Utility (use the RF GAIN calibration function, under Configuration).

This procedure calibrates both main and sub receivers.

A signal source is required.

Future firmware revisions will further improve accuracy, using the calibration data stored by this procedure.

Misc.

Improvements

• "SK" IS NO LONGER DISPLAYED IN RESPONSE TO NOISE DURING CW DECODE. Incorrect characters are now displayed as *.
• 6 METER SCANNING NO LONGER PROHIBITED. Scanning is limited to the 6-m U.S. ham band (50-54). Exception: In some countries the K3 wont operate on 6 m at all.
• TTY CENTER FREQ NOW DISPLAYED CORRECTLY: In FSK-D and AFSK-A modes, rotating SHIFT now shows the exact center pitch (when indicated by an asterisk). The four available center pitches are 1000, 1360, 1530, and 2210 Hz. Previously the pitch was rounded down to the nearest 50 Hz.

For Software Developers:

• "RO" COMMAND (RIT/XIT OFFSET READ/SET) ADDED. This command provides a more direct way to set up the RIT/XIT offset, as an alternative to ÒRUÓ and ÒRDÓ. Set/Response format:

ROsxxxx; where s is +/-, and xxxx is 0000-9999. Troubleshooting Aid:

• KAT3 ÒNOT INSTÓ setting is now global. If you set CONFIG: KAT3 to NOT INST for the present band/antenna, it applies to all bands/antennas.

Similarly, if you change the setting from NOT INST to any other setting, all per-band/per-antenna ATU mode data is restored. This change is useful if you need to remove a KAT3 module for troubleshooting.