Elecraft K3S firmware v3.57

MCU 3.57 / DSP 2.45

Misc.

Improvements

• TUNE SWITCH: ÒDouble beepÓ with NR on eliminated.
• DATA A: Loss of power when using TUNE corrected.

New Feature: Synchronous AM Receive

• SYNCHRONOUS AM: Outperforms regular AM du​ring selective fading.

Provides optional automatic VFO tracking of AM signals up to +/- 2.5 kHz.

Select AM mode, then hold ALT to select AM-S.

The -S icon flashes slowly if the signal is noisy.

Select AM-S LSB or USB using SHIFT; one of the two sidebands may reduce QRM.

Sync AM also works with diversity receive. (Note: Some AM broadcast stations encode their carrier, resulting in a low-pitched noise when Sync AM is turned on.) With Sync AM you can tune manually, or use automatic VFO tracking: -- If tuning manually, you need to tune to within +/- 10 Hz of the actual carrier frequency, at which point the K3 will phase-lock to the carrier. -- To enable VFO tracking, tap CWT, which turns on the T icon.

Or, tap SPOT to engage VFO tracking just long enough to lock.

When tracking is on, the VFO may ÒhuntÓ slowly across a span of several Hz.

IMPORTANT: For AM QSOs, use SPLIT mode when VFO tracking is turned on.

VFO B (TX) will remain fixed whi​le VFO A tracks RX signals.

Limitations: At present, VFO B cannot auto-tune in AM-S.

Also, both VFOs will always be in the same mode (AM-S LSB or USB).

Remote Control Command Changes:

• UP0/DN0/UP$0/DN$0 moves VFOs 1 Hz. Similarly, UP8 and UP9 move the VFOs by 100 and 200 Hz, respectively.