Elecraft K3S firmware v5.26

MCU 5.26 / DSP 2.83 / FPF 1.22

(First Combined K3S/K3 Release)

• USB COMPUTER PORT FOR COMBINED CONTROL and DIGITAL AUDIO (K3S, KIO3B): If a KIO3B module is installed (standard with the K3S), the CONFIG: RS232 menu entry will have a "USB" setting. If this setting is used, then a single USB cable can be used between the K3S and a computer to provide remote control, digitized line-level audio in/out, and PTT/KEY (via equivalents to the "RTS" and "DTR" signals). All of these signals are usually recognized by computer applications that also support RS232. This eliminates the need for a sound card and associated analog line in/out cables, as well as any external converter units. Refer to the K3S owner's manual, pgs. 18-20, for details.
• NEW P3 PANADAPTER CABLE SUPPORT (K3S, KIO3B): If a KIO3B module is installed, then the P3 Panadapter must be connected to the K3S at its RS232/P3 connector (RJ45). Two different special cables are available for this purpose,​ depending on whether a computer will be connected via USB or RS232 to the K3S and P3. Refer to the K3S owner's manual for details (pg. 18 and 19).
• LINE IN/OUT AUDIO USE WITH USB PORT (K3S, KIO3B): If a plug is inserted into the LINE IN jack on the K3S, this audio signal will override the digitized audio line-in data that is present in the USB cable. LINE OUT on the K3S, however, is always available even if the USB cable is being used for line-out.
• PREAMP 2 and CONFIG: PREAMP2 MENU ENTRY (KXV3B): This menu entry is only applicable if a KXV3B module is installed (supplied with the K3S). It also only applies if the current band is 12, 10, or 6 meters. If PREAMP2 is set to ON, then the PRE switch rotates through settings of OFF, PRE 1, and PRE 2 on the applicable band. PRE 2 turns on the low-noise preamp on the KXV3B module (+20 dB, with a typical NF of -144 dBm on 12/10/6 meters). When PRE 2 is selected, the PRE icon will flash slowly. Note: Do not use an external preamplifier (such as an Elecraft PR6 or PR6-10) when using the built-in low-noise preamp (PRE 2). This would result​ in excessive gain.

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• MULTIPLE ATTENUATOR SETTINGS and MAIN: ATTEN MENU ENTRY (K3S RF BOARD): On a K3S, the MAIN: ATTEN menu entry is used to select the per-band attenuation level for the ATTN switch (5/10/15 dB). A shortcut method of accessing this menu entry is to hold the ATTN switch for about 3 seconds. (On a K3, the parameter is fixed at 10 dB.)
• LOW-LOSS ATU BYPASS SETTING (KAT3A): The upgraded internal ATU option, the KAT3A, includes a very low-loss bypass path via an additional relay. The bypass relay is engaged when the ATU switch is used to turn the ATU icon OFF. This setting can be used with closely matched antennas. ("Bypass" mode on the earlier model KAT3 ATU uses a minimum-L/minimum-C network setting rather than a relay, result in a small dissipation loss that varies with frequency.)
• 100-500 KHZ SENSITIVITY IMPROVEMENT (KBPF3A): The KBPF3A is an upgrade from the KBPF3. The lowest-frequency filter in the KBPF3A has a cutoff at 100 kHz rather than 500 kHz. This improves typical sensitivity at 137 kHz (2200 meters) to about -120 dBm, and at 472 kHz (600 meters), about -130 dBm.
• UPDATED "PA" (PREAMP) REMOTE-CONTROL COMMAND (KXV3B): The PA command now supports a SET/RESPONSE value of "PA2" whenever preamp 2 is available. This applies on 12/10/6 meters with a KXV3B module installed and preamp 2 enabled (see CONFIG: PREAMP2 description, above).