SO2R

SO2R, short for Single Operator Two Radios, is a technique used in amateur radio contesting and DXing in which a single operator controls two independent transceivers to maximize efficiency. The operator can transmit on one radio while listening for, copying, and preparing responses on the other, with the goal of increasing QSO rate and multiplier opportunities across bands and modes.

A typical SO2R setup includes two transceivers, two antennas or a multi-port RF switching arrangement, and a computer running logging and control software. An SO2R controller or switch directs which radio is used for transmit, which remains in receive, and how PTT is activated. Operators often use macros or hotkeys to move quickly between radios, and may employ a separate receive path for each radio to minimize intermodulation and ensure clean copying. Some configurations use a single shared microphone or headset while isolating audio paths to prevent cross-talk.

In operation, the operator designates one radio as the main transmit channel and uses the other for searching, copying calls, and gathering multipliers. While CQing on the primary radio, the operator monitors the second radio for incoming calls, potential multipliers, or favorable split opportunities, and can rapidly switch transmit to the most advantageous radio. Effective SO2R practice requires good situation awareness, fast switching, disciplined logging, and careful RF management to avoid keying the wrong radio or creating interference.

History and adoption: SO2R emerged in the late 20th century as contesting equipment and software matured, becoming a standard technique among serious multi-band operators. Variants exist depending on equipment, band strategy, and operator preference. See also contest logging, split operation, and pileup handling.