QRP
| QRP | |
|---|---|
| Meaning | Low-power operating, from the Q-code for "reduce power" |
| Common definition | 5 W output or less on CW and data; 10 W PEP or less on SSB |
| Opposite | QRO, high power |
| QRPp | Under 1 W, often measured in milliwatts |
| Equipment and clubs | |
| Typical radios | QRP Labs kits, Elecraft KX2 and KX3, Icom IC-705, Yaesu FT-817 and FT-818 (discontinued) |
| Clubs | QRP ARCI (US), G-QRP Club (UK) |
| CW calling frequencies | 7.030 and 14.060 MHz, among others |
| Popular with | Portable operators, POTA and SOTA activators, kit builders, contesters |
QRP is operating with low transmitter power. The name comes from the Q-code QRP, "reduce your power", and the usual definition is 5 watts output or less on CW and data modes, or 10 watts peak envelope power (PEP) on single sideband. That is a twentieth of what a typical 100-watt transceiver puts out, yet QRP stations work every continent. Hams take up QRP for the challenge, for the small, light radios it allows, for the pleasure of building their own gear, and because it is the natural partner of portable operating.
Definitions
The 5-watt and 10-watt limits are those used by most QRP clubs, including QRP ARCI. Contest rules vary: many simply define the QRP category as 5 watts or less on any mode, so read each contest's rules. Field Day gives low-power stations a higher scoring multiplier. Power is measured at the transmitter's output, not as radiated power, so an operator is free to use the best antenna available.
QRPp is a term for very low power, usually under 1 watt. Milliwatt operators count their success in miles per watt, and some clubs offer awards for contacts of 1,000 miles or more per watt. The opposite of QRP is QRO, high power, usually meaning 100 watts or more, often with an amplifier.
Why it works
The difference between 100 watts and 5 watts sounds enormous, but it is 13 decibels, a little more than two S-units on a receiver's signal meter, where one S-unit is about 6 dB. A station that is S9 at 100 watts will typically be about S7 at 5 watts: weaker, but perfectly readable on a quiet band. The difference matters most when signals are already marginal.
Power affects only transmitting. An antenna improvement, by contrast, helps in both directions: a higher, more efficient or more directional antenna makes a QRP signal louder at the far end and makes the other station louder at home. That is why experienced QRP operators spend their money and effort on antennas first.
Mode matters too. CW concentrates all of the transmitter's power into a very narrow signal that the receiving operator can pick out with a narrow filter, and digital modes such as FT8 and WSPR decode signals far below the level needed for voice. WSPR beacons running a fraction of a watt are routinely heard thousands of miles away. Good timing helps as well: when a band is open, as it often is near the peak of the solar cycle, 5 watts crosses oceans easily.
Equipment
QRP radios are small, light and draw little current, which makes them easy to run from a small battery. Any radio whose output can be turned down to 5 watts can be used for QRP, but purpose-built rigs dominate.
- Kits. Building a radio has always been part of QRP culture, and many hams' first homebuilt transceiver is a QRP kit. QRP Labs sells inexpensive single-band and multiband CW and digital transceiver kits that have been built in large numbers. Classic kits such as the Heathkit HW-8 are still prized.
- Commercial radios. The Elecraft KX2 and KX3 are compact HF transceivers designed for portable use; the Icom IC-705 covers HF through 70 centimeters at up to 10 watts; and the Yaesu FT-817 and its successor, the FT-818, all-mode radios covering HF, VHF and UHF, were long the standard portable QRP rigs. The FT-818 has been discontinued, but both are common on the used market.
A good QRP station adds an efficient antenna, such as a dipole, an end-fed half-wave or a magnetic loop, and, for CW operators, a small paddle or key (see Morse keys and paddles).
Clubs and activities
The QRP Amateur Radio Club International (QRP ARCI), founded in 1961, is the main US club. It publishes QRP Quarterly, sponsors QRP contests and awards, and issues member numbers that are often exchanged on the air. In the UK, the G-QRP Club publishes the journal SPRAT and is known for its home-construction projects.
QRP operators gather around calling frequencies such as 7.030 and 14.060 MHz on CW. Low power is the norm in Parks on the Air and Summits on the Air activations, most major contests have QRP categories, and short QRP sprints run through the year.