How Low Can You Go? The World of QRP Operation


Newly minted hams like me generally find themselves asking, “What now?” after getting their tickets. Amateur radio has a lot of different sub-disciplines, ranging from volunteering for public service gigs to contesting, the closest thing the hobby has to a full-contact sport. But as I explore my options in the world of ham radio, I keep coming back to the one discipline that seems like the purest technical expression of the art and science of radio communication – low-power operation, or what’s known to hams as QRP. With QRP you can literally talk with someone across the planet on less power than it takes to run a night-light using a radio you built in an Altoids tin. Now that’s a challenge I can sink my teeth into.

Why QRP?

QRP takes its name from the Q-codes developed as shorthand by early Morse operators. QRP mean “Reduce power” or when posed as a question, “Shall I reduce power?” It has gradually morphed into a catch-all term that describes the whole field of low-power operation. Not surprisingly, there’s no hard and fast rule as to what constitutes QRP, but like a lot of things in life, you know it when you see it. Generally, any radio capable of transmitting at 5 watts or less would be considered a QRP rig, although some argue for anything below 10 watts. In the end these limits are academic, because most QRP aficionados like to work with much lower power, typically only a watt or two. Extreme QRP, called QRPp, lives below a watt and sometimes is best measured in milliwatts; for some serious over-achievers, it’s even measured in microwatts.

bb02_1
One way to QRP. W0CH

Why would anyone bother with handicapping themselves with such low power from the outset? Most commercially available rigs, like the Icom IC-7200 sitting in my shack, are capable of putting out 100 watts, and with even a marginal antenna I can make contacts around the world without much effort. If I wanted to I could attach a linear amplifier and start blasting out a kilowatt or more. But amateur radio operators in the USA are required by the FCC to “use the minimum transmitter power necessary to carry out the desired communications” (CFR§97.313(a)). So technically, if your rig is dialed up to 100 watts but you’re operating under conditions where 5 watts would do, you’re breaking the law. More importantly, though, it’s not good operating practice, and it contributes to QRM, or man-made interference, and with the ever-narrowing slivers of spectrum allocated to amateurs getting more and more crowded, it’s just not very neighborly. Learning how to make a contact with the power turned way down is a great tool to have in your arsenal.

But underneath the neighborliness and good spectrum hygiene, there’s an even better reason to make QRP contacts: because you can. Anyone can get their license, spend some dough on a transceiver, string a simple dipole antenna up in some trees and start yapping away at 100 watts. But a QRPer who can make the same contact using a twentieth of that power, and do so with a pocket-sized radio powered by a 9-volt battery? That shows skill and a deep understanding of radio. I think that’s the attraction for me.

QRP Gear

Most commercially available high-frequency (HF) transceivers are capable of being dialed back to QRP power levels, so chances are pretty good that most hams already have the gear needed to work QRP. And there are dedicated QRP rigs out there as well – Elecraft makes some sweet QRP radios with all the bells and whistles. But part of the allure of QRP is building your radio, and that’s what really fascinates me about the field. I’ve always had a pretty good handle on digital electronics, but analog circuits always seemed harder to grok. And RF circuits are just the stuff of wizards and demigods in my book. I want to change that, and I think being able to build my own transmitter would be a real hoot, and being able to understand the circuit at a really deep, fundamental level would be a game-changer for me.

RM2x
Classic Rockmite Altoids Tin QRP transceiver. WB3T.

With that in mind, where does one start with a homebrew QRP project? Unsurprisingly, the internet is chock full of plans and kits for everything from full-featured QRP rigs that can work single-sideband (SSB) and continuous wave (CW) modes to tiny CW-only transmitters that fit in an Altoids tin or even an old tuna can. If you get adventurous, you might even try building a QRP rig out of the guts of a cast-off CFL lamp.

The Altoids tin builds are a special sub-specialty of QRP – packable radios. With a pocket-sized radio, a few batteries, and a coil of wire for an antenna thrown into a backpack, you can communicate with the world from anywhere your feet can take you. This can prove handy, as it did for a young QRPer canoeing in Canada who wanted to reach his girlfriend in Ohio. Out of cell range but equipped with a 5 watt QRP rig, he made contact with a ham in Germany who sent an email to the young lady to let her know her boyfriend was alright and thinking of her. A roundabout route for sure, but QRP skills can be practical as well as fun.

PC010006_640
K8IQY‘s beautifully built SW30+30 QRP rig

One thing you’ll notice when you’re shopping for a QRP rig is the prevalence of CW-only transceivers. Continuous wave is the simplest mode of radio communication, using a radio signal of constant amplitude and frequency that’s either on or off. CW radios are simple to build and simple to run, and being a very low-bandwidth mode, CW is often able to punch through where more complex modes can’t, a decided advantage when you’re working QRP. The downside: you’ve got to learn Morse. That’s on my personal life list of skills, and when you think about it, how hard can it be to memorize about 40 symbols? Considering the doors it opens up, it’s a worthy investment.

Records are made to be broken

So just what’s possible with QRP? Are you going to be stuck making contacts across town? Or can you really reach out and touch someone across the planet? We’ve already seen that a Canada to Germany contact with 5 watts is possible, but how far can we stretch the limits of power and distance? As it turns out, pretty far. The current QRP miles per watt record is 1,650 miles from Oregon to Alaska on the 10-meter band using 1 microwatt! That’s the equivalent of 1.6 billion miles per watt. To put that feat into perspective, Pioneer 10 achieved “only” 850 million miles per watt before the space probe finally died in 2003, and it took a ground antenna that might not please the neighbors to pull that off. A little less extreme is the copying of a 40 microwatt CW beacon run by the North American QRP CW Club at 546 miles, or 13.5 million miles per watt. Just recently, the first solid-state rig to make a transatlantic contact entered the ARRL museum collection. The two-transistor radio sported 78 milliwatts on the 20-meter band; at a mere 47,500 miles per watt, it’s a more typical example of what QRPers accomplish every day.

Extreme examples aside, contacts of thousands of miles on just a few watts are happening all the time as hams push their rigs and their skills to the limit. You don’t have to shoot for a record to enjoy QRP – just set your sights low and give it a try.



Source link

Leave a Reply

Your email address will not be published. Required fields are marked *