Short answer: SO2R stands for single operator, two radios. One person runs on one radio while the second radio is used to search for a multiplier or to prepare the next QSO, and the operator switches between them quickly. It needs a few pieces of equipment, such as a way to hear both radios and to prevent transmitting on both, and a logging program that always knows which radio is active. Check the rules of your contest: in many contests SO2R is allowed within the single-operator category, but some categories restrict it.
What SO2R means
In an ordinary single-radio station, there is a great deal of waiting time in a contest. While you listen for a reply, while you wait for a pile-up to thin out or while the other station sends its exchange, your transmitter is idle and your attention is partly unused. SO2R fills that time. A second radio, normally on another band, looks for the next station while the first radio is calling CQ or exchanging.
The idea is not new, but modern interfaces and logging programs have made it more accessible. Still, it is a skill. It takes practice to listen to two audio streams, to know at every moment which radio you are transmitting on and to keep the log correct. Many operators start with a simple form and expand gradually.
Basic forms of SO2R
- Run plus search. One radio runs on a frequency, the other looks for multipliers on a different band. When a multiplier is found, you switch the transmit to the second radio, work the station, and return to the run.
- Two runs. More advanced: you call CQ on both radios alternately. It requires good timing and strong signals, and not all conditions allow it.
- Listening on the second radio only. A first step. The second radio is used as a receiver to find stations or to check another band for openings, but you transmit only on the main radio.
The first form is the one most operators learn first. It yields extra multipliers without changing the character of your run too much.
What the station needs
You do not need a complex setup to begin, but you do need some elements to avoid damage and interference.
- Two transceivers with the possibility to control them from the logger.
- Separate antennas for each band in use, and a way to avoid feeding both radios into the same antenna.
- Band-pass filters or stubs, so that the transmitter on one band does not overload the receiver on another band. This is the most frequent technical problem in SO2R, and it is very band-combination dependent.
- An SO2R interface (a switch box). It routes the microphone or keyer to the selected radio, the headphone audio to the correct ear, and ideally includes a transmit interlock that stops you from transmitting on both radios at once.
- Stereo headphones. The common arrangement is radio 1 in the left ear and radio 2 in the right ear, with the option to hear both in both ears.
- Software support. Your logging program should know which radio is active, switch the keyer or voice messages to it and log with the right frequency and band.
The details depend on your equipment and on the band combinations you use. Treat this list as a general outline, and read the manuals for your radios and your interface.
Logging two radios without mixing them up
For a log, SO2R adds a new type of error: the QSO that is recorded against the wrong radio. When you work a multiplier on radio 2 but your logger still thinks radio 1 is active, the band, frequency and sometimes the mode are written for the wrong radio. The QSO is real, but the line in the log is wrong, and for a committee a QSO on the wrong band is a QSO that cannot be matched with the other station’s entry.
Keep these rules to avoid it:
- Connect both radios to the logger. Let the program read the band and frequency itself, so that nothing relies on manual entry.
- Use the program’s SO2R mode. N1MM Logger+, DXLog and Win-Test all offer ways to work with two radios, but menu names and options differ by version, so refer to the manual of your program.
- Make the active radio visible. Watch the entry window colour or label that shows which radio will log the QSO, and train yourself to look at it before you press Enter.
- Do not change the focus during a QSO. If you move to the other radio while the exchange is incomplete, the logger may take the call from one radio and the frequency from the other.
- Test it before the contest. Work some test QSOs with both radios, export a Cabrillo and check the band and frequency columns.
For a reminder of how the QSO lines of a Cabrillo file are exported and what to check in the result, see our guide to exporting Cabrillo from N1MM Logger+, DXLog and Win-Test.
Callsign accuracy under divided attention
When you work two radios, your attention is divided, and the risk of copying errors is higher. A call that you copied on radio 2 while you were sending on radio 1 may be a partial copy. Typical results are busted calls, especially in the last character, and wrong exchange items. Some habits help.
- Confirm every call out loud or by keyboard before you log it. The extra second pays for itself.
- Do not log a call that you only half heard in the background. Let the other station repeat it.
- Limit the number of band changes in the first hours until your coordination is solid.
The article on busted callsigns describes these errors in more detail and how to prevent them.
Rules and categories
Whether SO2R is allowed depends on the contest and on the category. In many single-operator categories it is allowed. Some contests have a separate category that excludes it or an overlay class with limits on the equipment, and multi-operator categories have their own rules on the number of transmitters and band changes. Do not rely on a general article for this decision. Open the current rules of the contest you plan to enter, read the section on categories and, if needed, ask the organisers before the event.
Once you have chosen the category, declare it correctly in the Cabrillo header. Our guide to the Cabrillo header shows which fields are connected to the category.
What SO2R looks like in the statistics
Statistics are a good way to learn how your SO2R practice works in reality. If you compare hours before and after you began to use a second radio, a few figures matter: the rate by hour, the number of multipliers found during search periods, and the number of band changes that your log shows. QSOs by hour and band make the pattern easy to see, as do your countries, continents and zones. A good SO2R hour usually has a high rate on the run band and a steady trickle of multipliers from the second band. If the rate on the run band falls when the second radio is active, you may be paying too much attention to the search.
Contest Analyzer reads Cabrillo files from N1MM Logger+, DXLog and Win-Test and provides these statistics: rates, QSOs by hour and band, countries, continents, CQ and ITU zones, WPX prefixes, distance, beam heading, breaks and off time, and callsign length and structure. It also checks every callsign and every zone against official license databases and several independent reference sources and shows only the few QSOs worth a second look. You can edit calls and zones in the report and download a corrected Cabrillo. Dupes are not errors, and serial numbers are not checked. The contests page lists the 22 supported contests, and you can compare the result with your own earlier logs.
Starting step by step
- First get the second radio to listen only, and learn to follow two audio streams.
- Add the interface and the transmit interlock, and test the filters on the band pairs you plan to use.
- Practice with the logger in a quiet period, or in a smaller contest, before a big event.
- Review your log after each contest for wrong bands and for busted calls made while you switched radios.
Related reading
- Export Cabrillo from N1MM Logger+, DXLog and Win-Test
- Busted callsigns in contest logs
- Contest rates: QSOs per hour
The bottom line
SO2R lets one operator use the idle time of one radio to work with another. It needs the right equipment, careful logger setup and extra discipline with callsigns. Check that your category allows it, test the logging in advance and review the band and call columns afterwards. A clean log is a better result than a faster one that cannot be matched.
FAQ
Is SO2R allowed in every contest?
No. Many single-operator categories allow it, but some do not. Read the rules of the contest and category you enter.
Do I need a special logging program?
You need a program with support for two radios. Common contest loggers such as N1MM Logger+, DXLog and Win-Test offer it, but check the manual for your version.
What is the most common SO2R logging error?
A QSO logged against the wrong radio, which gives a wrong band or frequency. Test the setup and watch the active-radio indicator.
Does SO2R change how I should read my statistics?
Yes. Compare the rate on the run band and the multipliers found during search periods, and look at QSOs by hour and band.
Does Contest Analyzer detect SO2R?
It does not decide categories. It checks callsigns and zones and gives statistics, including QSOs by hour and band, which show your band-change pattern.
