Elecraft K3S firmware `v2.20`

Elecraft · Released Jul 24, 2008 · First seen Sep 14, 2026

v2.20 is not the latest firmware for the Elecraft K3S: the current version is v5.67 (January 22, 2019). Go to v5.67

In short — summary by updatemystuff.com

AGC linearized with lower threshold, audio artifacts eliminated, and UI improved.

Written from Elecraft's release notes, which are printed in full below.

Was this useful?

AGC: Slope is now approximately linear in dB. Threshold moved about 10 dB lower, closely matching earlier DSP revisions.
NR: Gain levels re-balanced to account for changes to AGC.
USER INTERFACE: Minor clean-up of menu entry text and parameters, help text, error messages, etc., to make operation more intuitive.
SUB RX ON/OFF now has no effect on SPLIT, RIT, or XIT.
SUB RX SYNTHESIZER is no longer updated when sub RX is turned off, even with VFOs linked. This prevents an audio artifact when tuning. Also eliminated interaction between main and sub synthesizers during T-R switching that was causing keying artifacts at very specific frequencies on some bands.
IIR DSP FILTER ON/OFF SELECTION now applies to both main and sub receivers. (IIR filter on/off is selected by tapping the 7 switch while in the FLx BW menu entry. IIR filters apply only to 100 Hz and narrower DSP bandwidths. They have slightly more ringing than the default FIR filters.)

updatemystuff.com never hosts firmware files — always download from the official source.

Create a free account and get an email the moment Elecraft publishes new firmware.