Elecraft K3S
firmware v4.86
Elecraft · Released Jun 9, 2014 · First seen Sep 14, 2026
Source:
elecraft.com
v4.86 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
Rear headphone jack switch logic inverted; reconfigure if speaker audio is missing.
- Rear headphone jack (KIO3) changed to component type with inverted switch logic
- Configure CONFIG:SPKR+PH to 'PH.R SW-' if experiencing missing speaker audio
Written from Elecraft's release notes, which are printed in full below.
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What's in this update
MCU 4.86 / DSP 2.83
- REAR HEADPHONE JACK CONTROL: The rear headphone jack (on the KIO3) was recently changed to a different type whose speaker-cutout switch logic is inverted from the original. If speaker audio is missing even without phones plugged in, you'll need to change the setup. Locate CONFIG: SPKR+PH, then tap '1' to switch to "PH.R SW-" (inverted). Tapping a second time reverts back to the original setting, "PH.R SW+".
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