Advanced Features

This page covers the advanced operating features of the K3/K3S that go beyond basic frequency, receiver, and transmitter control. These commands handle split operation, the optional sub receiver, diversity reception, memory channels, and several other features commonly used in contest and DX operations. For the complete alphabetical command listing, see the K3/K3S/KX3/KX2 CAT Command Reference.

Commands Used

Command	Description	GET	SET
FT	TX VFO select (split)	Yes	Yes
FR	RX VFO select	Yes	Yes
SB	Sub receiver on/off	Yes	Yes
DV	Diversity mode	Yes	Yes
MC	Memory channel	Yes	Yes
AN	Antenna select	Yes	Yes
AR	RX antenna	Yes	Yes
RT	RIT on/off	Yes	Yes
XT	XIT on/off	Yes	Yes
RU	RIT/XIT up	No	Yes
RD	RIT/XIT down	No	Yes
RC	RIT/XIT clear	No	Yes
RO	RIT/XIT offset	Yes	Yes
ES	ESSB mode	Yes	Yes
IF	General info query	Yes	No

1. Split Operation

Split operation means transmitting on a different frequency than you receive on. This is standard practice for working DX pileups, where the DX station listens on a frequency offset from their transmit frequency.

The FT command selects which VFO is used for transmit, and the FR command selects which VFO is used for receive.

• FT0; — transmit on VFO A (normal, simplex operation)
• FT1; — transmit on VFO B (split mode)
• FR0; — receive on VFO A (normal)
• FR1; — receive on VFO B

To set up a typical DX pileup split, set your receive frequency on VFO A, the DX station’s frequency on VFO B, and enable split:

FA00014195000;    RX frequency: 14.195 MHz
FB00014200000;    TX frequency: 14.200 MHz (the DX station)
FT1;              Transmit on VFO B

To cancel split and return to simplex operation:

FT0;              Transmit on VFO A (cancel split)

Tip

When working a DX pileup, you can adjust your transmit frequency by changing VFO B with FB commands while continuing to listen on VFO A. This lets you move around within the DX station’s listening range without losing your receive position.

2. Sub Receiver (K3 with KRX3 Option)

The K3 has an optional second receiver (KRX3) that allows simultaneous monitoring of two frequencies. When the sub receiver is enabled, VFO B controls the sub receiver frequency.

• SB0; — sub receiver off
• SB1; — sub receiver on
• When the sub receiver is on, VFO B controls the sub receiver frequency
• All $ commands (e.g., AG$, BW$, SM$) target the sub receiver
• SM$; reads the sub receiver S-meter

SB1;              Turn sub receiver on
FB00014250000;    Set sub receiver to 14.250 MHz
AG$120;           Set sub receiver AF gain to 120
SM$;              Read sub receiver S-meter
SB0;              Turn sub receiver off

Note

The sub receiver requires the KRX3 option. You can check whether KRX3 is installed by reading the OM; response — position 4 will show S if the KRX3 is present.

3. Diversity Mode (K3 Only)

Diversity reception uses both receivers on the same frequency with different antennas, allowing the DSP to combine the signals for improved reception. This is particularly useful for reducing fading on HF.

• DV0; — diversity mode off
• DV1; — diversity mode on

DV1;              Enable diversity reception
DV;               Query diversity state → DV1;
DV0;              Disable diversity reception

When diversity mode is active:

• Both receivers tune to the same frequency
• VFO B filter and mode settings are locked to match VFO A
• The main and sub antennas feed the two receivers independently
• The DSP combines the two received signals to reduce fading and improve signal quality

Caution

Diversity mode requires the KRX3 sub receiver option. Sending DV1; without the KRX3 installed will have no effect. Use two different antennas (or antenna paths) for the main and sub receiver inputs to get the full benefit of diversity reception.

4. Memory Channels

The K3/K3S provides 100 memory channels (000-099) that store frequency, mode, filter settings, and other parameters.

• MC; — query current memory channel
• MC000; to MC099; — recall a specific memory channel

MC;               Query current memory → MC042;
MC007;            Recall memory channel 7
MC000;            Recall memory channel 0

Note

Memory channels store the complete operating state: frequency, mode, filter bandwidth, and other settings. Recalling a memory channel changes all of these parameters at once. Writing to memory channels is done from the front panel.

5. Antenna Selection

The K3/K3S supports two antenna outputs and an optional RX-only antenna input.

TX/RX Antenna (AN)

AN;               Query antenna → AN1;
AN1;              Select ANT 1
AN2;              Select ANT 2

RX Antenna (AR)

The AR command enables or disables the separate RX-only antenna input on the rear panel. When enabled, the radio receives through the RX ANT jack instead of the main antenna.

AR;               Query RX antenna state → AR0; (off)
AR1;              Enable RX-only antenna
AR0;              Disable RX-only antenna (receive on main antenna)

Tip

The RX antenna input is useful for connecting a dedicated receive antenna (such as a Beverage or loop) that is optimized for low-noise reception. The radio automatically switches back to the main antenna for transmit.

6. RIT/XIT Offset

RIT (Receiver Incremental Tuning) offsets the receive frequency without changing the transmit frequency. XIT (Transmitter Incremental Tuning) offsets the transmit frequency without changing the receive frequency. Both are useful for fine-tuning one side of a QSO without disturbing the other.

RIT/XIT On/Off

RT;               Query RIT state → RT0; (off)
RT1;              Turn RIT on
RT0;              Turn RIT off

XT;               Query XIT state → XT0; (off)
XT1;              Turn XIT on
XT0;              Turn XIT off

Adjusting the Offset

RU;               Increment RIT/XIT offset up
RD;               Increment RIT/XIT offset down
RC;               Clear RIT/XIT offset to zero

Reading/Setting the Absolute Offset (RO)

The RO command reads or sets the RIT/XIT offset directly as a signed value in Hz.

RO;               Query offset → RO+00100; (+100 Hz)
RO+00100;         Set offset to +100 Hz
RO-00200;         Set offset to -200 Hz
RO 00000;         Set offset to zero

Note

RIT and XIT share the same offset value. Enabling both simultaneously applies the offset to both receive and transmit, which effectively cancels out the offset (since both sides are shifted by the same amount). In practice, you enable one or the other, not both.

7. Scanning

The K3 supports frequency scanning, controllable via menu and switch emulation commands. Scanning is not commonly used in programming applications but is available.

SWT09;            Start/stop scan (emulates the scan button)

The radio scans through frequencies or memory channels depending on the current scan configuration set via the front-panel menu.

8. ESSB (Extended Single Sideband)

ESSB mode extends the SSB transmit bandwidth from the standard ~2.8 kHz to approximately 4-5 kHz, enabling high-fidelity SSB audio.

ES;               Query ESSB state → ES0; (off)
ES1;              Enable ESSB mode
ES0;              Disable ESSB mode

Note

ESSB requires a wider IF filter and appropriate microphone/audio source to be effective. The wider transmit bandwidth uses more spectrum, so ESSB should only be used on relatively clear frequencies where the extra bandwidth will not cause interference to adjacent stations.

9. IF General Information Command

The IF command returns a comprehensive snapshot of the radio state in a single response. This is the most information-dense command available and is the response that gets sent automatically in AI1 mode on every front-panel change.

IF;  →  IF00014200000     0000000002000000 ;
        |              |   ||||||||||||||
        +- Frequency   |   |||||||||||||+- Reserved
                       |   ||||||||||||+-- VFO B in use
                       |   |||||||||||+--- Scan status
                       |   ||||||||||+---- Split
                       |   |||||||||+----- CTCSS
                       |   ||||||||+------ Reserved
                       |   |||||||+------- Mode (2=USB)
                       |   ||||||+-------- Data sub-mode
                       |   |||||+--------- RIT on/off
                       |   ||||+---------- XIT on/off
                       |   |||+----------- Memory channel
                       |   ||+------------ TX state
                       |   |+------------- Reserved
                       |   +-------------- RIT/XIT offset
                       +--- Padding/reserved

The IF response packs the following information into a single string:

• Current VFO frequency (11 digits)
• RIT/XIT offset
• TX state (transmitting or receiving)
• Memory channel number
• RIT and XIT on/off status
• Data sub-mode
• Operating mode (LSB, USB, CW, etc.)
• Split status
• Scan status
• Which VFO is active

Tip

Parsing the IF response is a good way to synchronize your application state with the radio on startup. Send IF; once to get a complete snapshot, then use AI2 mode for incremental updates. This avoids having to send individual GET commands for every parameter.

Practical Example: DX Pileup Setup

The following sequence configures the radio for working a DX station heard on 14.200 MHz that is listening up 5 kHz:

K31;              Enable extended command mode
FA00014195000;    Set VFO A to 14.195 MHz (your listening frequency)
FB00014200000;    Set VFO B to 14.200 MHz (DX station's frequency)
MD2;              USB mode
FT1;              Enable split (transmit on VFO B)
PC100;            Set power to 100 watts

After the QSO, clean up:

FT0;              Cancel split

Next Steps

Continue to Event Handling to learn about processing auto-information responses and keeping your application synchronized with the radio state.