Elecraft K3S firmware v1.87

MCU 1.87 / DSP 1.69

This release includes improvements in all areas. Changes are categorized below.

NEW FEATURES

• CW KEYING IN SSB MODES: While in SSB modes, you can now send CW without changing modes or using an offset. The other station will hear the signal at your CW pitch.

This is especially useful on VHF bands when SSB signals cant be copied. To enable this feature, go into CONFIG: CW WGHT and tap 1 until you see SSB +CW.

• FM MODE ADDED: Requires FM filter insta​lled in slot FL1. The bandwidth for FL1 must be set to 13.0 kHz. FL1 must also be set to ON for FM mode. Those not needing FM mode can set CONFIG: FM MODE to OFF. To set up a repeater offset: Use the CONFIG: RPT OFS menu entry, then hold ALT to select -/+/simplex (-/+ appear under the FM mode icon). To set up tone encode: hold PITCH, then rotate VFO B to select PL TONE or PL OFF, and rotate VFO A to select the desired CTCSS tone. (When PL TONE is on, a letter T will appear near the FM mode icon.) Repeater offsets and PL tones are stored per-band/per-memory.
• VARIABLE AMP KEYING DELAY: Added CONFIG: TX DLY menu entry, which sets the time from KEY OUT jack (active low) to first RF in 1-ms steps, from 8 to 20 ms.

To minimize loss of QSK speed, use the shortest delay that works with your amp. Most will work with the default (minimum) setting of 8 ms.

• LINE OUT ALLOWS RX/TX AUDIO RECORDING: Normally, CONFIG: LIN OUT sets a fixed-level, receive-only output for main/sub (L/R), compatible with digital modes. Tapping '1' switches LIN OUT to =PHONES, where the line outputs match headphone audio, audio level controlled by AF/SUB gain controls, and both RX and TX audio available.
• SIMULTANEOUS USE OF MIC AND LINE IN: If the MAIN: MIC+LIN menu entry is set to ON, and MIC SEL = FP or RP, the present mic OR line in can be used for transmit audio.

NOTE: Setting MIC SEL to LINE overrides the MIC+LIN menu entry (its parameter becomes "N-A"). When MIC+LIN is in effect, rotating the MIC control shows MIC GAIN. The op has to set MIC SEL to LINE temporarily to set LINE IN gain.

• S-METER ABSOLUTE MODE: Use the CONFIG: SMTR MD menu entry. Set to ABS (absolute) to have S-meter stay constant with preamp/atten settings. Default is NOR (where PRE/ATTN affect the S-meter). ABS mode requires recalibration (SMTR OF & SMTR SC).

RECEIVE

• SSB RECEIVE PASSBAND EXTENDED AT LOW END (now 100 Hz; was 200 Hz).
• AM RECEIVE WIDTH RANGE INCREASED: The WIDTH control in AM mode now has a range of 2.8 to 10.0 kHz. Wider settings provide outstanding fidelity for hi-fi speech and other wide-band signals. This is the *IF* filter bandwidth -- the traditional way to show bandwidth for AM, because the required IF bandwidth is twice the modulation bandwidth.

NORM selects an IF bandwidth of 6.0 kHz in this mode. WIDTH settings above 6.0 kHz will not be useful unless you have an FM-bandwidth crystal filter installed (at FL1).

• IF A 2.8 KHZ FILTER IS INSTALLED, SSB "NORM" BW is 2.8 kHz (was fixed at 2.7 kHz).
• AUTO-SPOT (SPOT with CWT ON) now works with both very weak and very strong signals.
• PSK AUTOTUNE ACCURACY improved. You may still need to use RIT (FINE steps) to tune in signals for best built-in text decode. (Also see CW-to-DATA in the Owners Manual.)

TRANSMIT

• TRANSVERTER POWER CONTROL: The value set in CONFIG: XVn PWR now correctly sets a fixed power level on the associated transverter band (0-1.50 mW or 0-12W).
• POWER ROLLBACK BASED ON REFLECTED POWER: Power rollback begins at about 2.5:1 at 100 W (and of course much higher SWRs are tolerated at lower power settings).

Recovers to original target power level after mismatch is corrected.

• CW QSK further refined, with smoother mute/unmute in the presence of QRN and QRM.
• SSB TRANSMIT BANDPASS EXTENDED AT LOW END. Improvement is about 2 dB at 300 Hz, 3 dB at 200 Hz, and 6 dB at 100 Hz. Additional improvement possible via TX EQ.
• SSB TX POWER CONTROL improved. Set ALC for about 5 bars (rarely 6+) using MIC gain control, then set CMP and POWER as desired. The RF power bargraph shows approx. peak power when you whistle or shout, but will typically show well below peak power during normal speech. If youre using an external peak-reading wattmeter or power amplifier, adjust POWER as required while observing the effect of speech peaks.

If you find that an SSB power setting higher or lower than for CW is often required, you may wish to compensate for this using the CONFIG: TXG VCE menu entry.

Technical Note: Our latest MCU and DSP code uses minimal amounts of ALC, consistent with analysis done by Leif Asbrink, SM5BSZ. (His findings and recommendations can be found on his web site, www.nitehawk.com/sm5bsz.) The general idea is to keep transmit drive just below where ALC can cause splatter on speech peaks, rather than apply ALC heavily to achieve additional compression.

CONTROLS

• A->B SWITCH: 1st tap copies frequency only; 2nd tap within 2 seconds copies mode and filter settings.
• VFO LOCK is no longer cancelled by VFO tuning controls (RATE, FINE, or COARSE).
• TUNING EITHER VFO ACROSS MULTIPLE BANDS now brings the other VFO along with it, so that both VFOs will always be on the same band. This eliminates the problem of bands getting out of sequence due to wide tuning excursions. (Later, well allow the subreceiver to be on a different band from main if CONFIG: VFO IND is enabled.)