March 25, 2008
Get Out Of The House
So many hams can no longer operate from home. Fortunately, modern QRP equipment is perfect for portable operation. Just head for the country, toss up an antenna, and get on the air. If only it were that simple!
George Dobbs, G3RJV, of G-QRP, once told me that in the U.K., QRP is a way of life. A simple lifestyle, simple radios, simple antennas. But the U.K. is small, and all of Europe lies within the distance from my house to Chicago. If you live on the U.S. West Coast, the Northeast or the Upper Midwest, you have a much higher ham-population density than in most of the country. Where you live should influence your choice of bands, and also antennas. As we voluntarily limit our power output to 5 W maximum, what separates the signals from the noise is the antenna.
So let's get this out of the way right now: Marginal antennas produce marginal results. Sure, a good location helps, but if you aren't putting enough rf into the ionosphere, at the right frequency, the right angle and in the right direction, you aren't going to make many contacts. Assuming it takes some effort to go afield, you want to make the most of your limited operating time.
Temporary Antenna Supports
I've been experimenting with a 20-foot (6-m) fishing pole as an antenna support. You can see photos here. I've tried several types of antenna, from random wires to a 20-M inverted vee. While I always make contacts, they are few and far between. From the flat terrain of South Florida (closer to the Bahamas and Cuba than the nearest state, Georgia), low antennas don't work very well. If you can get on top of a hill, though, such a support might work very well. You could use an inverted vee, or stretch a vertical wire for a 20-M vertical, or an inverted-L for 30 or 40 M.
Today I was experimenting with the minimum setup possible with this fishing rod, and I used 24-gauge solid speaker wire (Radio Shack 278-1509) as the feedline. To allow for quick band changes, I put alligator clips on the radiator wires, which are stranded 28-gauge hookup wire. I wanted to use a Ty-Wrap to secure the antenna to the tip of the rod, but the smallest ones I had were too wide, so I used mason's string.
The antenna is very light, and hardly bowed the rod.
The rod is a B&M "Black Widow," model BW-6, available online for about $12.00 plus shipping.
F5UKL/QRP heard me on 20, but couldn't copy me, so I decided to try a different antenna. The next one was about 28 feet (8.5 m) of wire running up the rod, with the excess tied off from the top with mason's string. I used a 16-foot (5 m) radial wire. To connect to this antenna I used a piece of RG-58, with a BNC male on one end and alligator clips on the other, that I bought at a hamfest. I prefer this cable to the binding-post-to-BNC adaptors because it doesn't strain the radio's BNC connector, which is only soldered to the circuit board, not held in place with a nut.
That antenna loaded up on 30 M, and I worked a station about 600 miles (1000 km) away, with a 589 report. But I didn't hear much else on 30, so I clipped on one leg of the 20-M inverted vee, which got the antenna to load on 40. Then I worked a station about 120 miles (190 km) away, with a 589 report. The next station I worked was in Kentucky, about 1000 miles (1600 km) away, also using a low antenna, but running 100 W. He had trouble copying me.
Forty and 30 M were the best bands for this antenna setup today, because in midday and early afternoon, they both offered some short skip. The ionospheric critical frequency, the highest frequency at which a signal radiated straight up will be reflected, was just high enough to give me good signal strengths in Alabama and Florida.
This map, from Australia's IPS Radio and Space Services, shows critical frequencies (FoF2) across North America at noon (EDT) on March 25, 2008. (March 2020 update: This service is no longer available. The current site doesn't provide North America maps.)
Noontime (EDT) Critical Frequencies, March 25, 2008
At my location, the critical frequeny just reaches 7 MHz. Short-skip propagation on 40 M is possible now, but higher frequencies will require a very low takeoff angle, so the signal just grazes the ionospheric F layer. From here to Europe looks pretty grim, while points to the southeast have promise -- except there isn't much activity from Africa. (I confirmed this FoF2 prediction by going to the park and getting on 40 CW shortly after uploading the above map. My first two contacts were with stations in Miami, and the signals were LOUD! Miami is too far away for groundwave, about 100 miles/160 km. In fact, the round-trip distance to the ionosphere and back probably wasn't much farther. But I'll take a 599 report any way I can get it!)
D-region absorption prevents 40-M signals from reaching Europe at noon. As the sun zenith moves farther west, 40 will open to Europe at relatively high angles. Just after local sunset, though, the F layer shifts, so that lower takeoff angles and fewer hops are required to work Europe on 40 after dark on this end. Unless your antenna concentrates energy at takeoff angles below 15 degrees, the best times to work Europe QRP from the U.S. East Coast are right around sunset.
On the longer hauls to Kentucky and Europe, the takeoff angles of signals from my low antennas were too high, and most of my signal was probably going right through the ionosphere into space. Maybe I'll get an SWL card from Mars. Still, on neither 30 or 40 M is a 20-foot-high antenna high enough. I was surely losing power into the dirt and the surrounding scrub growth. An antenna about 30-feet (about 10 m) high would probably work much, much better. There are several poles that long on the market, the best probably being the DK9SQ, sold by Kanga US in Michigan. It costs about $110 including postage in the U.S. If I didn't have access to some taller trees I would certainly consider getting one.
Solution: Find A Tall Tree
Fortunately, there are a few taller pine trees at this spot. I have a line over a 50-footer (16 m), and my 20-M inverted vee works great up there! I shot a light monofilament fishing line over the top with a slingshot, then pulled up 200-lb (90-kg) black, waxed Dacron line. I tied the ends of that line together, and leave it in place, tied down when not in use. So far, no one has stolen it. Running the KX1, I have worked Europe an hour before sunset on 40 M with a sloping dipole hung from that height. The difference in performance, listening and transmitting, between the low antennas and the high ones, is breathtaking.
I favor the inverted vee or a vertical because I need only one support. If you have a helper or time to spare, a dipole or loop (if you have a way to match its 100-ohm impedance) may work better in the directions they point. The critical factor for any antenna is, height and being clear of obstructions. I'll have more to say about that on the next page, which covers operating from home under less-than-great circumstances.