Old Anorak wrote: βWed Oct 04, 2023 9:09 am
Game over for pirate broadcasting- how depressing
I agree. It's sad. I built and operated my first land-based pirate station in 1969!
My first ever rig was a modified circuit from "Practical Wireless" -
https://www.worldradiohistory.com/hd2/I ... e-0047.pdf - modified for line level audio input, and moved downwards in frequency from "top band" - 1.8 MHz - down to ~1.5 MHz (the top end of the Medium Wave Band). It ran at around 11 Watts carrier, and could achieve arbout 93% modulation depth at best. Loaded into a sloping ΒΌ-wave aerial, and with an earth that used the local water supply pipes, it went for miles in the daytime!
Our "studio" was in the attic of our house, and used a sort of disco console effort with two Garrard turntables, a "Geloso" microphone, a home-made mixer and a Philips reel-to-reel tape recorder. I discovered the need for compression of the audio, so built a crude optical compressor that had appeared in an American magazine a year or two before. Considering that we were a bunch of schoolkids at the time, it sounded pretty good!
After some months of almost daily operation, the lads from the PTT (the Post Office Telecommunications Department) paid us a visit. They examined my homebrew rig, and told me to dismantle it and stop broadcasting. We stayed off the air for six days (as I remember) and then we were back - on an adjacent frequency - for another couple of months. On the second visit, they impounded the rig!
Within two weeks, I'd built another, but with an 813 valve instead of the 807, and with a secondhand guitar amplifier as its modulator! This was considerably more powerful, and caused some interference to local TVs until I tamed its tendency for VHF spurs! Again it sounded good, and we got our first letter from a listener in another country.....
The bug had well and truly bitten by then, and there was no looking back. Transmitters got more powerful and more sophisticated, and in 1972, I made my first VHF transmitter.... 15 Watts of mono from a QQV03-12 valve.....