How low can you go?

Foundations of Amateur Radio

It's common knowledge that power, as in output power, makes your signal heard in more places. If you've followed my adventures you'll also know that I'm a firm believer in low power or QRP operation.

It all started when I was told that my shiny new amateur license was rubbish because I was only allowed to use 10 Watts. Seemingly the whole community around me shared that opinion and slogans like "life's too short for QRP" are still commonly heard.

As a direct result of that sentiment I decided to explore and document just how much I could actually do with my so-called introductory license, the Australian Foundation License. I've now held it for over a decade and I'm still exploring and writing.

One of my first acts of rebellion was to lower my radio output power to its minimum setting of 5 Watts and half legal power was sufficient to prove my point.

Although I'm still regularly being encouraged to upgrade, my second act of defiance is to keep my Foundation License until I decide that I need more. I'll let you know if it ever happens.

One more well known so-called "fact" about our hobby is that if you use low power you'll really only get anywhere on the higher bands, 2m, 70cm and above. There's plenty of reports of amateurs using a low power handheld radio to talk to the International Space Station and my own satellite internet used 1 Watt to get to geostationary orbit. On HF on the other hand, 5 Watts is as low as you really want to go. Making contacts is a struggle and often frustrating, but when you do, bliss!

About a year ago I took delivery of a WSPR beacon. It's capable of transmitting on all my accessible HF bands using 200 mW. Given my antenna situation I've configured it to transmit on the 10m band, 24 hours a day, thunderstorms excepted. When making the purchase decision I had no insight into how my beacon would perform. 200 mW is stretching even my love of low power, but I hooked it up and turned it on and waited.

It came as quite a surprise that my beacon was heard over 15 thousand kilometres away, not once, not a couple of times, but regularly. When I came up with my November challenge to see if I could improve on that I made an almost throw away comment about reducing power to see if I could still make the distance.

A couple of weeks ago I hooked up a 6 dB attenuator to my beacon, reducing the power from 200 down to 50 mW. It came as quite a surprise that my signal made it to the same receiver in the Canary Islands. My kilometre per Watt calculation shot up, quadrupling my previous record.

Just imagine, 50 mW making its way over a third of the way around the globe, bouncing between the ionosphere and the planet, just like any other HF signal. At that point I realised I had learnt a few things. You don't need stupid power to make a distant contact on HF either. I started wondering just how little power was needed to get out of the shack.

Yesterday I hooked up a 10 dB attenuator and within ten hours my now 20 mW beacon broke my own kilometre per Watt record again and based on the signal to noise numbers from previous contacts, I see no reason for that record to stand for very long. Once that happens I've got plenty more attenuators to play with and I'm not afraid to use them.

Now I'm on the hunt for an attenuator that will reduce my main radio output from 5 Watts. I'm told I should aim for double the power rating, but I also have to consider how to connect my antenna coupler which needs 10 Watts to tune, but that's a project for another day

When was the last time that you used really low power?

I'm Onno VK6FLAB