the concept of operating a transmitter at low power


QRP Defined

The operation of a transmitter at power levels that do not exceed 5 watts (CW). Pure QRP is when the effective radiated power (ERP), or the calculated power (incl. all gains and losses), does not exceed 5 watts. Many stations running QRP power levels are also using multi-element directional antennae that actually boost the ERP well above 5 watts. Put this way, pure QRP is when an operator runs less than 5 watts into an antenna that has no effective gain.

Back to the index.

Concepts of QRP Operation

The concept of operating a radio transmitter at power levels of less than 5 watts is nothing new by any means. Only recently, though, has the idea taken off. QRP is the term commonly associated with "low power" communications. It is derived from one of the common "Q" signals (abbreviated statements) that means "please reduce power."

QRP can be great fun. It can also be greatly aggravating. Let's look at the facts, though. Assuming an "S" unit (signal strength meter reading) is 6 dB, decreasing the transmit power from 100 watts to 10 watts results in an "S" meter reading decrease of 2. In other words, if the "S" meter reads S8 for a station running 100 watts, and that station then reduces transmit power 90 watts (to 10 watts), the "S" meter will read S7 (assuming, again, that the "S" unit is 6dB). Not too much of a difference, really.

QRP is a bug. Just like DXing is a bug, once you are bitten by the QRP bug, you normally make QRPing one of your amateur radio "claims" to fame. For the most part, QRP is a cw operating mode. SSB is just too inefficient for reliable communications, unless you are just talking down the block, or ridge-top to ridge-top. Do keep in mind, though that the ARRL does sponsor a QRP phone contest. As a result, QRP is sometimes considered an "elitst" activity among radio ops. Well . . . it is. Not many people are running QRP (on a relative scale). Therefore, we are elitists . . .but not by choice. It would be great if more people were using QRP. Unfortunately, not many people think QRP is possible during the "low times" of sunspot cycle 23. They are wrong. Dead wrong. I would invite them to check out K3WWP's Ham radio Activities from the link-section below.

Back to the index.

Benefits of Operating QRP

There are hidden benefits to operating QRP:

As you can see, there are quite a few benefits to operating QRP. Besides being a member of a special group of hams who enjoy cw, you could also be a special member of a group of those hams who enjoy cw and QRP. But don't take my word for it. Go...see for yourself the joys of QRP cw, or even ssb.

Back to the index.

Further QRP Operating Theory

You also may be wondering why QRP is predominantly a CW "operation." Well, that's easy enought to explain. Think about the bandspace that SSB takes compared to CW. At the very least, SSB requires about 3 kHz or so, whreas cw only needs about 500 Hz with filtering. Note: don't quote me on this until I get the real numbers. With this in mind, imagine putting a 5 watt SSB signal on the air (5 watts peak or average, the model works for both). You are going to have to spread that 5 watts over 3 kHz of band space. Now imagine that same 5 watts of RF on the air via a CW signal. That 5 watts will only have to be spread over 500 Hz of band space. So, you see, it is much like spreading peanut butter on bread: for a given amount of peanut butter, the less space you have to spread it over (i.e. the smaller the bread), the thicker that layer of peanut butter is going to be. Correlate the peanut butter with the RF and you will see that CW will "concentrate" the RF while SSB more or less dissipates the RF. You get more "bang" for your buck.

Some other reasons CW is the mode much better suited to QRP operation are because CW is much less prone to lid-style operation, courtesy is a big issue among us CW folk (not to say that SSB afficinados are rude), more of us can fit in the band than can SSB operators or digital hams, and finally, it is much easier to hear one single tone--of 800Hz or so--than it is to hear mutli-tones ranging over 3kHz (or thereabouts).

Back to the index.

QRP Links

Back to the index.

Back to the main radio page.

Last Modified: 3/1/98