Elecraft K3S
firmware v5.40
Elecraft · Released Nov 11, 2015 · First seen Sep 14, 2026
Source:
elecraft.com
v5.40 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
PA temperature sensing algorithm selection for 12/10m bands to mitigate interference
- Two PA temperature-sensing modes for 12/10m: 'T AND R' (default) or 'R ONLY'
- 'R ONLY' uses RFI-resistant sensing in TX mode for SWR/grounding issues
- 6 meter band always uses 'R ONLY' temperature-sensing method
Written from Elecraft's release notes, which are printed in full below.
Was this useful? Thanks.
What's in this update
MCU 5.40 / DSP 2.86 / FPF 1.25
- PA TEMP MENU FUNCTION CHANGE: Tapping '1' in CONFIG: PA TEMP selects one of two PA temperature-sensing algorithms for use on 12 and 10 m: "T AND R" or "R ONLY". The default is "T AND R" (normal 12/10 m PA temp sensing in both TX and RX modes). The "R ONLY" selection should be used if PA temperature sensing on these higher bands may be affected by higher load SWR, poor grounding, or supply voltage drop. In this case, normal temp sensing is done only in RX mode, while in TX mode, sensing is done in a way that minimizes sensor error due to RFI. 6 meters always uses the R ONLY method.
updatemystuff.com never hosts firmware files — always download from the official source.
Get it from ElecraftWatch the K3S for updates
Create a free account and get an email the moment Elecraft publishes new firmware.
Create account & watch