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ARDF
Amateur Radio Direction Finding(Fox Hunting)
“International Style”
Thomas KrahnKT5TK / DL4MDW
Fox Hunting Should this be stopped?
ARDF International Rules
● Find 5 hidden transmitters by using a portable receiver with a directional antenna
● The foxes must be found before a maximum time limit. Ranking: 1.) Number of foxes in time limit. 2.) Time at finish line
● The transmitters are under time control. Each TX sends for one minute its ID, then the next fox is switched on. (5 minute total cycle)
● Typically used: 80 m CW Morse code,2 m AM modulated Morse code
ARDF Fox IDs
● MOE – – – – – .● MOI – – – – – ..● MOS – – – – – ...● MOH – – – – – ….● MO5 – – – – – …..
● Long dashes good for direction finding● Count the dots to know which fox it is
ARDF Frequencies
● 80 m: 3.579 MHz (NTSC color carrier frequency) 5th fox sometimes on different frequency (homing fox)
● 2 m: 144.500 MHz (Europe), 146.565 MHz (official IARU region II)
ARDF Transmitters
● Control logic usually micro-controller● Time synchronization of all 5 foxes difficult● TX power 1 – 5 Watts● 2 m: Antenna cross dipole ● 80 m: Grounding wires,
Tent pegs, 50 ft wire● Close to the transmitter good
visible flag and punch station.
ARDF Transmitters
ARDF Receivers 2m
“Water Level” Housing
Long Version
Traditional German Version
Photos by DF1FO
ARDF Antennas 2 m2 Element HB9CV
4 Element Log Periodic
3 Element Yagi Russian Version
Moxon Rectangle
Photos by DF1FO
ARDF Receivers 80 m
ARDF Receivers 80 m
DF1FO 2010
1947
SM5IQ 1953
WB6BYU QST 9/2005
VK8YNG
OE6GC
PJ-80
ARDF Antennas 80 m
Frame Antenna:10 wire cable in circular aluminum tubeforming a coil. Circular tube must havean isolated gap! 6 dB more sensitive than ferrite rods
Photos by DF1FO
Ferrite Rods:longer = betterWatch out for surplus bars withfurrows!
Not all ferrite bars work at 3.5 MHzSelect by try & error only
ARDF Orientation Gear
● GPS usually not allowed● Compass● Map
● Appropriate sport clothing● Sturdy shoes● Carry some drink● Rope your glasses around neck
ARDF Strategy● Start with the fox with the loudest signal● Plan a round course (No zigzag)● Make sure to watch the clock and arrive at the
finish line before the max. time● Do not trust other fox hunters● If there are hills, always choose a
route on the top of a ridge. Careful with reflections in valleys
ARDF Competitions
● 28-30 May 2011 Shropshire ARDF FestivalLudlow, England, UK
● 5-10 September 2011 18th IARU Region I ARDF ChampionshipsOradea, Romania
● 16-18 September 2011 6th IARU Region II ARDF ChampionshipsAlbuquerque, New Mexico
● 23-28 September 2011 5th IARU Region III ARDF ChampionshipsVictoria, Australia
● September 2012 16th World ARDF ChampionshipsSerbia
● September 2014 17th World ARDF ChampionshipsAstana, Kazakhstan
ARDF Web Links
● http://en.wikipedia.org/wiki/Amateur_radio_direction_finding
● http://www.ardf-r2.org/
● http://www.homingin.com
● http://www.texasardf.org
● http://www.darc.de/referate/ardf/english.htm
● http://www.mydarc.de/df1fo/indexeng.html
● http://www.rac.ca/en/amateur-radio/operating-technical/ardf/
● http://www.pejla.se/ardf_games.htm
● http://www.kkn.net/mailman/listinfo/ardf