On September 5, 1977 NASA launched the Voyager 1 space probe from Cape Canaveral to study the outer Solar System. The little guy just kept on going into interstellar space, still transmitting out of its twelve foot dish antenna, blissfully unaware that QRP doesn’t work. Well, Voyager cheated a little, I do too sometimes, by using twenty three Watts of power, still almost 538 million miles per Watt. Imagine waiting more than thirty seven and a half hour to get a reply to your CQ! Sure, Earth has big ears, but let’s not tarnish NASA’s golden record; pun intended.
Back down to Earth, are we? Some amateurs use levels of power that if not your head, will make your electricity meter spin. How much power do we need? The FCC says as little as possible to make a decent contact. Some play with micro-Watts and get through; millions of miles per Watt. Transceiver manufacturers seem to have settled on one hundred Watts, a number most likely based on marketing and economical factors rather than real life applications. One hundred is a nice round number. I am a big fan of QRP, or rather, ultra-portable radios, usually five to ten Watts. My friend Ray and I used to experiment with reduced power down to one hundred milliwatts over more than eight hundred miles; CW of course. Why signal with a flashlight when you can use a laser pointer? I was making regular contacts to Eastern Europe from Florida using from one to five Watts to about six thousand miles. Power is expensive, in dollars, Amperes and kilograms.
The military figured it out long ago. They deal with life-and-death communications from the field, portable man-pack operations in HF, which is still in use, just not the only option anymore. My RT-320 outputs about twenty five Watts, as do most military portable transceivers.
Power does help, nobody can deny it. There is however the law of diminishing returns. When the ionosphere isn’t cooperating no amount of power will get through. When it does, you don’t need much to be heard. A good resonant antenna and some knowledge will go a long way. I bet inadequate antennas radiating only a few Watts rather than the hundred coming out of the transceiver are the norm rather than the exception.
I suggest any new Hams to save their money, study antenna designs and spend an afternoon at the hardware store. Amplifiers are mostly used for contests where the goal is not to make contact but crush the competition. Better chase losses, hunt for noise sources, use better aerials and more efficient modes like CW or PSK-31.
I believe the magic numbers are five Watts CW and twenty five Watts SSB. You can go on a nice DXpedition for the price of an amplifier. If someone doesn’t believe how well they hear your five Watts, tell them the story of the little probe that could.