To those new to the hobby of Amateur Radio, hearing the term QRP often raises questions: What is QRP? Why do some hams choose to operate QRP? How can I operate QRP? These are good questions, and all are worth asking. This article will attempt to answer these questions.
What is QRP?
The Q-signal QRP means "please reduce power". Today, QRP means to operate using low power, and a ham is said to be operating QRP when his CW output power is 5 watts or less or his SSB output is 10 watts or less. At first glance 5 watts doesn't seem like much power, so how can anyone communicate at QRP levels? Actually, the signal produced by a QRPer running 5 watts isn't that much weaker than the signal from a 100 watt transmitter. By dropping output power from 100 watts to 5 watts, the signal strength at the receiving station drops by 13dB. If the 100 watt signal measured S8 at the receiving station, the 5 watt signal would be approximately 2 S-units down, or S5--providing solid copy unless the band is very crowded. (Similarly, the difference between a 1000 watt signal and a 5 watt signal is only 4 S-units.) Not only are domestic contacts possible when running QRP power levels, even distant DX can be worked--sometimes easily--when running QRP. For example, WD8RIF has on more than one occasion worked Australia on 40m CW while running 5 watts into a dipole.
Why do some hams choose to operate QRP?
There are probably as many reasons hams choose to run QRP as there are hams running QRP. Some hams choose to run QRP to inject a challenge back into their hobby; they may have achieved DXCC the traditional "kilowatt" way and now are chasing DXCC using only QRP power levels, or maybe they've honed their contesting skills and station to the point that operating the contest at 1500 watts--or even 100 watts--is no longer a challenge, and they now try to "run the frequency" and "maintain the rates" while running only QRP power levels. Others hams choose to run QRP to help reduce interference on the bands. Others enjoy the ability to operate radio from "from the field" with simple and lightweight yet competent equipment. An entire QRP station consisting of a modern single-band CW transceiver, key, and antenna can fit into a pocket, yet the rig can boast receiver performance comparable to the best commercial rigs and can run for an entire weekend on a small battery, allowing operations from locations where traditional higher-power operations would be difficult or impossible due to the weight of higher-power transceivers and high-capacity power sources.
How can I operate QRP?
The easiest way to try out QRP is to turn down the output power on an existing commercial HF rig. Most commercial HF rigs have provisions, often via a front-panel control, to reduce the transmit power. If a rig lacks such a control, a simple ALC bias-supply circuit can be built to reduce the rig's output power. (Click for a circuit from QRP Power by the ARRL.)
For the home-station rig, a commercial HF rig is makes a fine QRP rig--indeed, some will argue that a state-of-the-art commercial HF rig makes the best QRP rig due to the commercial rig's excellent receiver performance and QRM-fighting tools--but for field or portable use, a commercial 100 watt transceiver is too big and too battery-hungry.
QRP rigs can be very small and very frugal with power requirements, and given the simple designs possible for low-power operation, QRP is a natural for the home-brewer. Good, easy-to-build designs are available in several ARRL publications as well as in books and periodicals by other publishers. Alternately, there are numerous excellent and easy-to-build kits are available. For example, the "Simple Superhet Transceiver" (SST) CW transceiver kit by Wilderness Radio features a true superhet receiver, two-watts of clean RF output, a three-pole crystal filter, stable VXO tuning, and a parts count of only 80 components, and comes complete with all components, circuit board, and a 1.5"x3.2"x3.5" enclosure--all for $80. The SST is tiny and draws only 15mA on receive--so a small battery will power this rig for a long time. (URLs for Wilderness Radio and other kit suppliers can be found at the end of this article.)
While SSB can be used successfully at QRP power levels, CW is the most popular mode and is a natural for QRP due to CW's efficiency and signal-to-noise ratio performance. QRP operation can and does occur in all portions of all the bands, but much of it occurs around the "QRP Calling Frequencies":
|3.710 US Novice|
|7.110 US Novice|
|28.110 US Novice|
For those interested in QRP operations there are several organizations worth joining:
Please note that the above list is by no means exhaustive. URLs to these organizations can be found at the end of this article.
This article was written to answer the questions "What is QRP?", "Why do some hams choose to run QRP?", and "How do I operate QRP?". QRP was defined to be operations occurring at low power. Hams choose to run QRP for numerous reasons, including to inject a challenge back into their hobby and to allow radio operations from locations where traditional higher-power operations would be difficult or impossible. QRP operations can be easy; a commercial HF rig can be used as a QRP rig and QRP rigs are simple enough that they can easily be built from scratch or from inexpensive yet high-performance kits.
Links to more information (URLs updated 2008-01-18)