Getting Started In QRP - Operating From Home

March 24, 2008

Operating From Home
Everything I said about marginal antennas and high and in the clear antennas on the last page, applies everywhere, of course. Sometimes, though, our home situations don't lend themselves to good antennas. If you can put up high antennas or even beams, you probably don't need to read this page.

The KR1S Situation
I confess, I sometimes run high power, although I haven't run more than 4 W in more than a year at this writing. You can see my antenna situation here. Actually, I'm very lucky to have those two trees, though I have to wait until after dark to use them. I leave the same type of Dacron line I mentioned on the previous page, in those trees, but it still takes time to put up and take down the antennas -- in the dark. Maybe you aren't so lucky.

Indoor Antennas
Indoor antennas rarely work as well as outdoor antennas, unless you live in a tall, wooden building on a hill. Indoor antennas pick up noise generated by appliances, and may radiate enough to interfere with television reception. In any case, a fair amount of signal is swallowed by house wiring, ducting and gutters.

It's always tempting to try to make one antenna work on many bands, especially when you can have only one antenna. Enter the antenna tuner, and maybe open-wire transmission lines. You should recognize, though, that many antenna tuners are very lossy, and you may be giving up almost half your transmitted (and received) power in the tuner. Off-resonance antennas often have weird radiation patterns as well. Just because you can get a match to the antenna, and even if it does radiate some power, if that power isn't going in the right directions and vertical angles, you're wasting electrons and time. An indoor antenna gives you something to listen with, and may provide some contacts, but consider other alternatives. If you can't use outdoor antennas, operate portable whenever possible, from good locations.

Unfortunately, QRP operators often oversimplify their stations. A simple radio still needs a good antenna, though not necessarily a complicated one. But a resonant dipole 30 feet (10 m) or higher will produce astounding results when compared with almost anything you can set up indoors. In my book, Low Profile Amateur Radio (First Edition; the Second Edition is completely different), I included quite a bit of information on small loop antennas, often called "magnetic loops," though they are not magnetic. Properly constructed and well maintained, these loops will radiate a signal, but their small size, and the likelihood that they will be used near the ground, makes them less suitable for QRP.

Mobile Antennas For Home (Or Portable) Use
Let's face it: There is no free lunch. If short mobile antennas like HamSticks and Hustlers worked as well as full-sized dipoles, no one would use dipoles. Most mobile stations are radiating at QRP levels, though they don't know it. Such antennas may radiate only 10-percent of the power they absorb; the rest is dissipated as heat. If you're going mobile and that's all that will fit on your vehicle, go ahead. I worked W2XYZ Mobile/QRP on 20 CW last week, and gave him a 559. My antenna was an inverted vee at 50 feet (16 m), and he gave me a 569! For home or portable use on the HF bands, avoid mobile antennas.

A Quick Word On Baluns
Getting non-resonant antennas to load up with a tuner often involves a balun. Baluns usually have several turns of wire on a ferrite core, either toroidal or binocular. I haven't done extensive testing yet, but my experience over the years has been that these baluns introduce significant losses. The greater the mismatch the higher the losses. If you have no choice you have no choice, but I always try to use a resonant antenna that will match the radio without the need for a tuner, whether I'm running QRP or high power. I have the internal tuner option in my KX1, and a couple of tuners at home, but I try hard to never need them. Put your power where it will do the most good: Into the antenna, not lost in the matching network.



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