The HF radio spectrum is divided up into bands by international treaty. My interest, however, has always centred on the international broadcast bands. Transmissions from every nation and culture provide rich, varied and challenging content all around the clock. First hand geographical insight. Every shade of political philosophy. A complete and unfiltered view of all humanity.
Well, perhaps not quite as filtered as it would be from a single source. There are 5 stages of filtering of the truth behind what one hears as "news".
Therefore, unfiltered, in the context of short wave listening, can mean only that stages 3 and 4 are circumvented - which is nonetheless an improvement.
I became keen on amateur radio while at school, passing my Radio Amateur's exam in August 1961. At first I listened to the amateur bands with interest. However, what I heard was so boring that my interest waned. This I feel was far more to do with the Draconian restrictions imposed by governments on what amateurs may talk about on air than it was to do with their personalities. I never took out an Amateur Radio licence.
My interest in the intercontinental aeronautical bands stems from my career work on flight simulators and aircraft navigation. These were concerned with LF and VHF navigation aids. However, they did invoke a curiosity about the other side of aeronautical radio, namely communications. Although the most active traffic is on the VHF air band, in-flight communications between VIP passengers and their ground offices are sometimes carried on HF. However, this is rare and mostly unstimulating. Listening to private conversations between people I do not know does not hold my interest long. Neither does the other and more major content of the HF air bands: continuously repeated weather reports.
Maritime bands held the same fleeting interest. Conversations between people you don't know rapidly lose their intrigue. The same goes for those specialised weather forecasts. Signals from over-the-horizon radars, ionospheric research stations and distant galaxies could be interesting if only one had the means of interpreting them.
I built my own receivers. My first short wave receiver was the Practical Wireless 'Short Wave 3' which I built while still at school. It was a TRF and hence not very selective.
After trying fruitlessly to revive a No 19 tank transceiver, I bought a government surplus Canadian Marconi No 9 Set. It was big and heavy. However, although it only covered 1.5 to 4.5 MHz, its stability and good performance made it ideal for attaching front-end converters to cover other bands. It did a good job and was going strong when I gave it away years later.
During a summer vacation from college, I built a Heathkit Mohecan. This was one of the first all-transistor short wave receivers. It was a long-serving friend which was finally laid to rest in the local rubbish skip in July 1997!
These old receivers had a kind of character which is now hidden in the otherwise far superior PC-driven virtual receivers of today.