HF Direction finding


Posted on Feb 6, 2014

The main requirements are only a directional antenna (ie a ferrite rod or frame) and a screened case for the works of the set. In the past some competitors have modified ordinary medium wave receivers to cover 160m by retuning the front end. However, most `serious` competitors now have purpose-built sets suitably `ruggedised` to take the inevitable knocks, and of course the competitor also takes the knocks,


HF Direction finding
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so be warned. In the early years of DF, all the receivers were battery valve sets. These progressed to discrete component transistor sets, but with the advance in technology most of the best receivers in use today use the basic inte- grated circuit design that will be described later in this article. The overall cost of what is a rather useful 160m receiver is no more than £20-30 with judicious purchasing at local rallies. I would define the sport of DFing as `finding a deliberately well hidden transmitter (and its crew) by taking cross bearings with a suitable radio receiver and physical searching in the immediate locale of the transmitter site`. As I intimated above, it is a `sport` for all ages and all professions, as indeed is amateur radio in general. Anyone can take part, and all are very welcome to do so. It is advisable, however, firstly to team up with an existing competitor, to gain experience in the wiles of the sadistic TX crews and get a feel for the behaviour of LF signals and receiver performance. It is no good leaving the car five miles from the Tx because the signal was so strong. Many of the competitors will present a lecture to a club and organise a local club event as a demonstration, or for the less fit, put on an indoor computer based competition which can be just as cut throat as the real thing. First contact should be through the National RSGB Direction Finding committee who will then organise a...




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