Elecraft K3S
firmware v3.77
Elecraft · Released Feb 27, 2010 · First seen Sep 14, 2026
Source:
elecraft.com
v3.77 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
Fixes frequency offset in diversity mode, sub-receiver band-pass filter selection, and audio artifacts in BIN mode.
- Corrected frequency offset between main and sub receivers during transmit with VFO movement
- Fixed sub receiver band-pass filter selection when using independent band selection for dual receivers
- Eliminated audio artifacts in AFX BIN audio effect
Written from Elecraft's release notes, which are printed in full below.
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What's in this update
MCU 3.77 / DSP 2.53
- DIVERSITY MODE MAIN/SUB RECEIVER OFFSET FIXED:
In some cases a small frequency offset between the main and sub receiver could be introduced due to transmitting while moving VFO A or the RIT offset. This no longer occurs.
- SUB RECEIVER BAND-PASS FILTER SWITCHING FIXED:
If the main and sub receivers were configured for independent band selection (CONFIG: VFO IND = YES), switching the main receiver to any of 17-10 m may have caused an incorrect band-pass filter to be selected for the sub receiver.
- SYNTHESIZER PLL TABLES UPDATED: Reduces the DDS tuning range slightly to minimize group delay through the DDS crystal filter. (These tables are located in the ÒHFPF0108Ó file, part of the firmware release package.)
- AFX ÒBINÓ MODE FIX: Stability improvement for the ÒBINÓ audio effect (selected by MAIN: AFX). Previously, a loud audio artifact could occur under certain receive-signal circumstances.
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