� Media: 73 Review Foxhunting from Melbourne to Nottingham The headline reads, as Joe Moell writes his 'Homing In' column in the April 2001 edition of the American magazine, 73 Amateur Radio Today. He continues with an interesting section about the trials and tribulations of radio foxhunters in Melbourne Australia. The focus then switches to 'Merry Olde England' as he puts it, and he regales a tale about Nottingham transmitter hunters and their sneaky tactics to try to find the wily fox. Comparing the Australian unattended hidden transmitters with the Nottingham 'foxes' (that comprise one or two radio amateurs hiding with a transmitter). He recalls some of the lengths these foxes will go to, in order to conceal themselves. One example is where the 'fox' is dressed as a fisherman in the midst of a fishing competition. It took the hunters quite a while to test the strength of their convictions and approach the fox. Fishermen can be very serious! Then there was the 'fox' dressed as a tough motorcyclist in amongst a crowd of his biker pals in a pub garden. It was very amusing to see the hunter's unease. They kept looking over at the motorcyclists trying to pluck up courage to make a move. To keep from being heard when the hunters are nearby, one clever fox used a laptop computer and soundcard connected to the transmitter. The sound of his voice having been recorded earlier (along with unusual sound effects to 'throw' the hunters). Joe then begins to write about the hunting system used by myself G6UWO and John G0PSI. Serialised over June and July issues, Joe describes the RDF system which is based around an idea first used by wartime submarine hunters. Rotating a small beam antenna, and plotting the signal strength as it rotates on a cathode ray tube, was all that was required. However things are always more easily said than done, and he goes on to reveal the facts about the 'Nottingham Secret Weapon'. It all started with tests on our home made Doppler hunting system, whilst amazingly sensitive due to its tracking filter, we felt we needed a system with even greater sensitivity. One of the main problems with Doppler systems is that when used in areas where there are lots of reflections (multipath) the doppler will tend to lock onto the strongest signal, even if it is a reflection. Many of our hunts took us into built up areas which the fox would choose on purpose of course to mask his whereabouts. We decided to build our 'whirligig' to overcome these problems and so began several years of development. Unbeknown to us at this time T' hunters in the USA had a head start in this technology, in fact about a 40 year head start!. The late W6DTR had made a hand rotated polar display system for use on 75 metres. According to Joe, he used a war surplus high persistence radar tube and was virtually unbeatable, being far in advance of any of his contemporaries. There have in fact been five different examples of visits to this idea reported over the years in Joe's column 'Homing In.' The first one we encountered, was when we had our prototype system up and running. It was built by Jami Smith KK6CU of Pasedena. We contacted him via snail mail and he gave us some helpful hints on aerial development, but also sent us a copy of the Homing In article. So now we had found out about Joe, his magazine articles and the Homing In website. We contacted Joe, told him about our system and the ideas we had to use modern technology to develop it further.. He was very encouraging and said it was about time this idea was aired again and to contact him when the fully fledged system was up and running. A year on and a few gallons of 'midnight oil' later and we were ready to go public. Rather than go to great lengths to reiterate the whole development story, I have decided to just reproduce the information on the final design here. copyright © silent design associates. 2001. all rights reserved.