Elecraft K3S firmware `v5.35`

Elecraft · Released Aug 20, 2015 · First seen Sep 14, 2026

v5.35 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

Prevents attenuator menu from accepting invalid 0 dB setting and improves command compatibility.

Attenuator ON level menu no longer accepts 0 dB as a value
RA01 and RA10 commands both now select 10 dB attenuation for K3 application compatibility

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

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MAIN: ATTEN MENU ENTRY NO LONGER GETS SET TO 0 DB: This menu entry sets the per-band attenuator ON level (5, 10, or 15 dB for the K3S, 10 dB fixed for the K3). In the previous firmware release, MAIN: ATTEN could be set to 0 dB by computer logging/control applications. This is not a valid parameter value. Once the menu entry is set to the desired ON value, the attenuator itself is turned on/off by the ATT switch. (Holding ATT for 3 seconds is a shortcut into the menu entry.) For Application Developers:
"RA01" and "RA10" COMMANDS BOTH SELECT 10-dB RX ATTN VALUE: The K3's RA set command for 10 dB Is RA01. The K3S uses actual dB values, so for 10 dB, RA10 is normally used. (The K3S can also accept RA05 and RA15.) To improve compatibility with unmodified K3 applications, the K3S now allows either RA01 or RA10 for 10 dB. The GET response uses whichever SET format was received last.

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