QRP means transmitting with low power: by common agreement 5 W output on CW and digital modes, and 10 W peak envelope power on SSB. It is a deliberate constraint, in the way that fly fishing is a deliberate constraint, and it produces operators with unusually good ears and unusually good antennas.
Why it works
Dropping from 100 W to 5 W costs 13 dB — a little over two S-units. That sounds fatal and is not, because the other station's receiver is usually limited by noise and by their antenna, not by your transmitter:
- Above about S5 the other operator hears you fine, and most of your 100 W was surplus.
- The same 13 dB can often be bought back with antenna height, a better antenna, or waiting for the band to open — none of which need a power supply.
- CW and modern digital modes are far more efficient per watt than SSB. FT8 decodes signals well below the noise floor, which is why 5 W of FT8 routinely crosses oceans.
What you need
- A radio. The QRP market is enormous: the Elecraft KX2 and KX3, Yaesu FT-818, Icom IC-705, Xiegu G90, the QMX and QCX kits from QRP Labs, and the (tr)uSDX among many others. Kits are a legitimate route; see kits and homebrewing.
- The best antenna you can manage. This matters more than the radio. A resonant dipole up 30 feet will beat a compromise vertical every time.
- Batteries. A 5 W station runs for a whole weekend on a small lithium iron phosphate pack; see power, supplies and batteries.
- Patience and a good headset.
Operating technique
- Answer other people's calls rather than calling CQ into a busy band. Tail-ending a station who has just finished a contact is the highest-percentage move in QRP.
- Listen for stations that are not in a pileup. A rare station that everyone is chasing is a poor QRP target; the same station an hour later, calling CQ with no takers, is an easy contact.
- Send your call twice and be ready to repeat. Do not append "/QRP" — it is not a legal identifier and lengthens what the other operator has to copy.
- Use the openings. Gray line, the first hour of a band opening, and the quiet part of a contest weekend all favor small signals.
- Spot yourself on the Reverse Beacon Network or the PSK/WSPR reporters and see who is hearing you. It is the cheapest propagation research there is.
The community
QRP ARCI, the G-QRP Club, the Flying Pigs and the Four State QRP Group run their own contests, publish journals and issue awards; the Reverse Beacon Network and WSPR let you measure your reach without a single contact. Field events such as the QRP-to-the-Field and Freeze weekends pair naturally with parks and summits operating, where low power and battery operation are the norm anyway.
If you want a number to chase, the "1000 miles per watt" award for a contact whose distance divided by your power exceeds that figure is a classic, and is more achievable on 6 m sporadic-E than most people expect.