Direction Finding

There was an article in RADCOM in the last year.

About DF Hunts

Direction Finding (DF) Hunts, which are also sometimes known as "Fox Hunts", are where club members use their radio operating skills to find a transmitting station. A prize is awarded to the person who does best in this activity over the year.

Only a receiver is needed to take part in these hunts (although frequencies do vary). Often, there will be receivers for loan whenever a DF Hunt takes place.

Gloucester club has a long tradition of holding 'walking distance' DF hunts on 160-metres. Each year, one Saturday afternoon in late summer, Vernon and Tony would find a quiet spot in the countryside, and about 2pm would put out the initial DF calls for the half-dozen or so GARES members assembled about a half-mile distant.

Usually the start had taken place only after a period of frantic activity at the transmitter site (because a connector had broken in an awkward place, the antenna was not loading up properly, TX power seemed down, or we had chosen an ants nest.)

It was very good fun, not least at the end when we all drove to a local tea room and cream teas. Depending on support, we might well re-instate this event in our busy club calendar.

Anyway, for the winter months, the second series of mini-DF hunts in the dark is now well under way. We have found that there was no need to use oblique, gnomic, zenithal maps of Churchdown, neither would we need to know the current value of Magnetic Deviation. Also, Cliff's point source transmitter has meant that near, intermediate and far fields may remain a complete mystery to us.

Tony is beginning to believe that he might do just as well unencumbered with a receiver at all, and use the increased mobility to keep ahead of the pack! During one of the practice sessions, Steve T was wandering around in the dark, testing his receiver at extreme range. Typical of what happens on DF hunts, the transmitter was transferred back inside whilst he was thus engaged, taking the signal with it!

Back to the old days in the Forest of Dean, Gerry T always did the hunts on 2-metres with a 5-ele Yagi. 2-metre DF in dense woodland is very difficult, but Gerry spread his team out either side and commenced his run-in. So Gerry's wife found the TX without possessing a receiver!

Another memorable DF hunt in Dean Forest was when the TX team lay hidden behind a camouflage net, watching Leta W about five yards away. Despite the strong smell of jute from the netting that she noticed, we remained undiscovered at the time.

If we re-instate the DF hunts proper, intending competitors should take careful note of the 'zone of silence', which has nothing to do with antenna polar diagrams, it means that you have wandered (inadvertently?) close to the TX site, and are under observation from 'the team', who have now shut down the TX to try and keep you away.

In the mini-DF series so far: Steve (G8IUN) is in the lead, followed by Vernon, Brian, Graeme. and Andy.

Various related links

http://www.ardf.btinternet.co.uk/index.html

http://www.ardf.btinternet.co.uk/rules.html

http://www.ardf-uk.co.uk/begin.html

http://www.gpss.tripoduk.com/df1.htm

http://www.frars.org.uk/cgi-bin/render.pl

http://www.geocities.com/andrewm2kk/directionfinding/index.html

http://www.forjac.freeserve.co.uk/df.htm

http://myweb.tiscali.co.uk/mkars/ARDF.htm

http://www.blackburnworld.co.uk/wadarc/