Voice, CW & Data

This page covers the commands used for mode-specific operations: SSB voice, AM/FM, CW keying and text sending, and digital/data modes. For operating mode selection and DATA sub-mode basics, see Frequency & Modes. For the complete alphabetical command listing, see the K3/K3S/KX3/KX2 CAT Command Reference.

SSB Voice Operation

SSB (Single Sideband) is the most common voice mode on HF. The K3/K3S supports both LSB and USB, with convention dictating which to use based on frequency.

Mode Setup

MD1;                 Set LSB (Lower Sideband)
MD2;                 Set USB (Upper Sideband)

Note

By convention, LSB is used below 10 MHz and USB is used above 10 MHz. This is not enforced by the radio — you can select either sideband on any frequency — but following the convention ensures other stations can hear you.

Microphone Gain

The MG command controls microphone gain, affecting how much audio drive reaches the transmitter.

MG;                  Query mic gain → MG030;
MG030;               Set mic gain to 30

The valid range is 000 to 060.

Speech Compression

The CP command enables and controls the speech compressor, which increases average power by reducing the dynamic range of voice audio.

CP;                  Query compression → CP015;
CP000;               Compression off
CP015;               Set compression to 15

The valid range is 000 to 040, where 000 disables compression.

Tip

Start with compression at 000 (off) and increase gradually. Typical values are 010 to 020 for casual operation. Higher values increase average power but can degrade audio quality if overdriven.

TX Equalizer

The TE command enables or disables the transmit audio equalizer, which shapes the frequency response of your transmitted audio.

TE;                  Query TX EQ state
TE1;                 Enable TX equalizer
TE0;                 Disable TX equalizer

Extended SSB (ESSB)

The ES command controls Extended SSB mode, which widens the transmit audio bandwidth beyond the standard SSB passband for higher-fidelity voice.

ES;                  Query ESSB state
ES1;                 Enable Extended SSB
ES0;                 Disable Extended SSB

Caution

ESSB transmits a wider audio signal that occupies more spectrum. Use it only when band conditions and adjacent-channel spacing allow. It is not appropriate for crowded band conditions or contests.

Monitor Level

The ML command sets the transmit monitor level, allowing you to hear your own transmitted audio through the headphones or speaker.

ML;                  Query monitor level
ML020;               Set monitor level to 20

AM/FM Operation

AM Mode

MD5;                 Set AM mode

AM uses both sidebands and a carrier. The K3/K3S can both transmit and receive AM.

FM Mode

MD4;                 Set FM mode

In FM mode, the squelch control is particularly important for muting noise when no signal is present.

SQ;                  Query squelch level
SQ020;               Set squelch level to 20

Note

FM deviation, CTCSS tone encode/decode, and repeater offset settings are configured through the menu system. Use the MN command to navigate menus and MP to read or set menu parameter values. These settings are not available as direct commands.

CW Operation

CW (Morse code) mode provides a rich set of commands for keyer speed, sidetone, text sending, and break-in timing.

Key Commands

Command	Description	Range
KS	Keyer speed (WPM)	008-050
KY	Send CW text from buffer	up to 24 chars
CW	Sidetone pitch	0300-0990 Hz
AP	CW APF (audio peaking filter)	0/1
SD	QSK delay	000-255

CW Keyer Speed

The KS command reads or sets the internal keyer speed in words per minute.

KS;                  Query keyer speed → KS020;
KS020;               Set keyer speed to 20 WPM
KS030;               Set keyer speed to 30 WPM

Sidetone Pitch

The CW command controls the CW sidetone frequency, which also sets the receive audio center frequency for CW mode.

CW;                  Query sidetone pitch → CW0600;
CW0600;              Set sidetone to 600 Hz

Audio Peaking Filter (APF)

The AP command enables or disables the CW audio peaking filter, which narrows the receive audio response around the sidetone frequency.

AP0;                 Disable APF
AP1;                 Enable APF

Sending CW from Computer (KY Command)

The KY command sends up to 24 characters of CW text through the radio’s internal keyer. This is the primary method for computer-generated CW.

KY CQ CQ CQ DE W1AW ;

Supported characters include letters, numbers, and common punctuation. The @ character inserts a prosign — the character before @ and after @ are sent as a single merged character:

KY AR@;              Send AR prosign
KY BT@;              Send BT prosign

Caution

You must wait for the buffer to empty before sending more text. Sending a KY command while the buffer is still full will result in lost characters.

Buffer Status (TB Command)

The TB command checks how many characters remain in the CW text buffer.

TB;                  Query buffer → TB012; (12 chars remaining)
TB;                  Query buffer → TB000; (buffer empty, safe to send)

A response of TB000; means the buffer is empty and ready to accept another KY command.

CW Buffered Sending Sequence

The following diagram shows the recommended pattern for sending CW text from a computer, including buffer management:

Tip

For contest or rapid CW sending, poll TB; every 50-100 ms to keep the buffer fed without gaps. This provides smooth, continuous CW output from arbitrarily long text.

QSK (Full Break-In)

The SD command controls the QSK delay — the time the radio waits after the last CW element before returning to receive.

SD000;               Zero delay — full QSK (hear between characters)
SD010;               Short delay
SD100;               Longer hang time (semi-break-in)

Full QSK (SD000;) lets you hear between individual CW elements, which is useful for detecting stations that break in during your transmission. Higher values provide semi-break-in with a longer hang time, reducing the clicking effect of rapid TX/RX switching.

DATA Mode Operation

DATA mode is used for all digital communication: FT8/FT4 (WSJT-X), RTTY, PSK31, JS8Call, and other sound-card or direct-keying modes.

Sub-Mode Selection

First set DATA mode, then select the sub-mode with DT:

MD6;                 Set DATA mode (or MD9; for DATA-REV)

Command	Sub-Mode	Description
DT0;	DATA A	Sound card digital modes via MIC/LINE input (most common)
DT1;	AFSK A	Audio FSK via MIC input
DT2;	FSK D	Direct FSK keying via KEY jack
DT3;	PSK D	Direct PSK via accessory port

DATA A (Sound Card Modes) — Most Common

DATA A is the sub-mode used with WSJT-X (FT8/FT4), fldigi, JS8Call, and most modern digital mode software. Audio is routed between the computer sound card and the radio via the LINE IN/LINE OUT connections.

MD6;                 Set DATA mode
DT0;                 DATA A sub-mode
PC005;               Low power for digital (typically 5-15W)

Tip

For FT8 and other digital modes, DATA A (DT0;) with USB-based audio via sound card is the standard configuration. The K3’s LINE IN/LINE OUT on the KIO3 board provides clean audio paths.

FSK D (Direct FSK)

FSK D is used for RTTY with hardware FSK keying. The KEY jack on the rear panel provides the direct FSK keying input.

MD6;                 Set DATA mode
DT2;                 FSK D sub-mode

This bypasses the sound card entirely, using direct digital keying for cleaner RTTY signals.

DATA-REV

MD9; sets DATA-REV mode, which reverses the sideband used for data transmission. This is occasionally needed for compatibility with certain digital mode configurations.

MD9;                 Set DATA-REV mode
DT0;                 DATA A sub-mode (reversed sideband)

Voice Message Playback

The KDVR3 option (digital voice recorder) enables recording and playback of voice messages. Four voice message slots are available, triggered via the SWT command which emulates front-panel button taps.

SWT33;               Play voice message 1
SWT34;               Play voice message 2
SWT35;               Play voice message 3
SWT36;               Play voice message 4

Note

Voice message playback requires the KDVR3 option to be installed. You can verify its presence by checking position 5 of the OM response — a D in that position indicates the KDVR3 is installed. See Connection & Discovery for details on the OM command.

Next Steps

Continue to Advanced Features for split operation, sub receiver control, diversity reception, and memory channels.