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Doing it with milliwatts
At least some amateurs are competitive and like to measure their achievements against others. In the early days of HF radio it was all about distance. Then, as worldwide contacts became more common
(at least on bands like 20 metres) from the 1930s it became DX countries worked. Though long distances continued to be sought for the more challenging DX bands such as 1.8 and 3.5 MHz along
with VHF, UHF and higher.
QRPers came up with another way of comparing their achievements. Instead of a straight distance worked they divided it by power. Called 'Miles per Watt' it sought to compensate for lower power.
A still-available award called '1000 miles per watt' was launched. You'd qualify if you worked 10000 miles with 10 watts, 1000 miles with 1 watt or 100 miles with 100mW. This is not very scientific;
double the power does not double the distance and half the power does not halve the distance. Consequently the easiest way to reach 1000 miles per watt is not to seek increased distance
as much as to seek to cover a given distance with progressively lower output powers.
Which brings us to milliwatts. Single hop HF, sporadic-E lower VHF and enhanced tropospheric VHF/UHF propagation are all low-loss propagation modes. Milliwatts can readily carry several hundred to
a couple of thousand kilometres via these means. This is even with common transmitting modes such as CW and SSB. Stations in low noise areas are best placed to hear you. If you can, go portable to
a low-noise location to maximise your chance of hearing others, including those running low power. Don't know what to expect from a low noise location?
These videos show how even low powers can punch through.
The following demonstrates some of what milliwatts can achieve.
Milliwatts from a hand-powered CW transmitter (500mW)
CW vs SSB under noisy conditions
Milliwatts HF SSB
Milliwatt contesting (down to 20mW)
Homebrew milliwatt DSB beacon (40mW)
Milliwatts with slow scan TV (down to 20mW)
Milliwatts (and microwatts) WSPR
A spontaneous 144 MHz opening (down to 500mW)
Tests with down to 8mW SSB on 80m
Items were chosen for likely usefulness and a satisfaction rating of 4/5 or better.
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Books by VK3YE
Ham Radio Get Started (USA)Australian Ham Radio Handbook (Aust) More Hand-carried QRP Antennas 99 things you can do with Amateur Radio Getting back into Amateur Radio Illustrated International Ham Radio Dictionary Make your Passion Pay (ebook writing)
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