Links for RDF, T-hunting, and Radio-Orienteering
Find out how to get involved in mobile T-hunts in your area of the USA by visiting these local T-hunt Web sites.
(Listings are alphabetical by state and city.)
- Phoenix, AZ
- Prescott, AZ
- Anderson, CA, near Redding
- Clovis, CA
- Fremont, CA
- Los Angeles, CA area Saturday night and All-Day hunts (old site)
- Results and photos of Los Angeles and San Diego area mobile hunts are now at this new site
- Mission Viejo, CA and the rest of southern Orange County
- Placerville, CA and El Dorado County
- San Diego, CA area including La Mesa and El Cajon Site 1 and Site 2
- San Francisco, CA area
- Santa Clarita, CA
- Stockton, CA and the California Central Valley
- Thousand Oaks, CA, also Ventura, Oxnard, Camarillo and southern Ventura County
- Boulder, CO
- Meriden, CT
- Broward, FL Flamingo Net
- Daytona Beach, FL
- Palm Beach, FL
- Chicago, IL and suburbs hunt schedule, also Chicago FM Club hunt page and Society Radio Operators monthly foxhunting reports
- Kankakee, IL
- Boston, MA
- Pittsfield, MA and northern Berkshire area
- Baltimore, MD
- Fort Washington, MD
- Holland, MI and other parts of the state
- Lansing, MI
- Salisbury, NC and Rowan County
- Trenton, NJ and the Delaware Valley
- Las Vegas, NV
- Lake County, OH
- Portage County, OH, near Peoria
- Pottstown, PA, including Berks, Chester and Montgomery Counties
- Richardson, TX
- Salt Lake City, UT
- Alexandria, VA
- Staunton, VA
- Pullman, WA
- Racine, WI
Some localities have regular (or occasional) mobile T-hunts, but no Web coverage of them. Find out
about hunts in the areas below by sending e-mail to the local Homing In Correspondent (Listings are alphabetical by state and city. E-mail addresses have been obscured to foil spammers. Replace "-at-" with "@" when addressing your e-mail.): Santa Barbara Amateur Radio Club, host of the Fourth USA ARDF Championships in 2004 and the Seventh USA ARDF Championships in 2007
- Phoenix, AZ via Byon Garrabrant N6BG (byon-at-byonics.com)
- South Windsor, CT via Art Grondine N1WSM (drwho-at-ntplx.net), including Hartford area
- Dover, DE via Sam Guccione K3BY (sguccion-at-outland.dtcc.edu), also Virginia/Maryland peninsula
- Titusville, FL via Bud Hughes K4CWG (bhughes-at-expedient.com)
- Atlanta, GA via Jim Sorenson KA4IIA (ka4iia-at-radio.org)
- Honolulu, HI via Russell Houlton WH7O (r_houlton-at-compuserve.com)
- Indianapolis, IN via Clifford Vaught N9FHF (foxhunt-at-in.net)
- South Bend, IN via Myer Blatt N9OCA (n9oca-at-aol.com)
- Doylestown, OH via Silver Creek Amateur Radio Association (w8wky-at-amsat.org), including Akron/Canton area
- Shelby County, OH via Dale Kubichek N6JSX (n6jsx-at-yahoo.com)
- Toledo, OH via Vince Vassello KB8TEP (kb8tep-at-arrl.net)
- Oklahoma City, OK via Charlie Shelden KC5NBH (shelden3-at-ionet.net)
- Locust Grove, OK area via Rich Conn KD5JXU (yonkersmtham-at-chouteautel.com)
- Portland, OR via Dale Hunt WB6BYU (wb6byu-at-arrl.net), also Salem, OR and Vancouver, WA
- Harrisburg, PA via Dale Snyder N3KXC (dsnyder-at-postoffice.ptd.net), also Reading and Lancaster
- Greene County, VA via Jack Smith KE4LWT (ke4lwt-at-arrl.net)
- Port Angeles, WA via Neil Robin WA7NBF (neil-at-robin-wood.com)
- Madison, WI via Thomas Baden KE6CBR (roo-at-ham9.net)
- Milwaukee, WI via Paul Gruettner WB9ODQ (wb9odq-at-sbcglobal.net)
Non-commercial Web sites regarding technical RDF topics have been posted by these individuals and groups (alphabetical by last name):
Mobile T-hunting is not limited to the USA. Here are some other places around the world where it is done:
- Adelaide, Australia Web site by VK5ZCF
- Canberra, Australia Web site by VK1KNP
- Urunga, Australia Web site about Urunga Convention on Easter weekend with foxhunts
- Belgium by ON5NV (in Flemish)
- Barry, Ontario, Canada Web site
- Belleville, Ontario, Canada Web site
- York/Newmarket region, Ontario, Canada Web site
- Peterborough, Ontario, Canada Web site
- Montreal, Quebec, Canada Web site
- Basingstoke, England Web site by Basingstoke Amateur Radio Club
- Nottingham, England Web site by AR Club of Nottingham
- Bangalore, India Web page
- Annual Balloon Foxhunt in Netherlands on 2 and 80 Meters
- Portugal by AMRAD-Portugal (in Portuguese)
- Portugal by CT2IZV (in Portuguese)
- Spain by EA7BDD (in Spanish)
- 160 Meter Band in UK
the Tenth USA ARDF Championships in 2010 and the Seventeenth USA ARDF Championships in 2017
On-foot foxhunting (also called foxtailing, radio-orienteering and ARDF) is growing rapidly in the USA. In addition to southern California ARDF events and upcoming championship news at this site, you can see these other sites for information on stateside ARDF activities:
Texas ARDF in Houston and Austin area, host of the Eighth USA ARDF Championships in 2008
ARDF USA, based in Texas
Here are e-mail contacts for radio-orienteering leaders in other parts of the USA and Canada (Listings are alphabetical by state/province/city. E-mail addresses have been obscured to foil spammers. Replace "-at-" with "@" when addressing your e-mail.):
- Victoria, BC via Joe Young VE7BFK (jyoung-at-islandnet.com), ARDF Coordinator for Canada (RAC)
- Los Angeles and Orange County, CA via Joe Moell KØOV (k0ov-at-homingin.com), ARDF Coordinator for USA (ARRL)
- Pleasanton, CA via Bob Cooley KF6VSE (rccooley-at-comcast.net)
- Santa Barbara, CA via Marvin Johnston KE6HTS (marvin-at-west.net)
- Denver, CO via Larry Benko WØQE (w0qe-at-bnk.com)
- Baltimore, MD via "Mac" McNeeley W3DQT (mdflatlands-at-yahoo.com)
- Bozeman, MT via Harley Leach KI7XF (ki7xf-at-yahoo.com)
- Portland, OR via Dale Hunt WB6BYU (wb6byu-at-arrl.net), ARDF Coordinator for IARU Region 2 (North and South America)
ARDF is the predominant style of RDF contesting outside the USA. There are Web sites about it in many countries (in English unless otherwise indicated).
Here are the past and present sellers of equipment and software for RDF and related purposes to the Amateur Radio market, in alphabetical order. A listing here does not imply an endorsement of products.
Also see my Hardware Sources page for links to suppliers of circuit boards, special parts, and complete kits for RDF-related home construction projects.
- Agrelo Engineering -- Agrelo's microtransmitter products and the DFjr doppler add-on for FM receivers are no longer available. The company went out of business in 1998. SWS Security in Maryland, which took over production when Agrelo Engineering folded, is also out of business. This link goes to a cached archive of the Agrelo Web site as it was in its heyday. If you have a non-working DFjr or are considering purchase of a used DFjr, check the Using and Improving the Agrelo DFjr Doppler Set page of this Homing In site.
- AHHA! Solutions -- Former producer of the popular MicroFinder Doppler kit, which went out of production in January 2006. This link goes to an cached archive of the former Ahha! Web site.
- Arrow Antenna -- Manufacturer of lightweight VHF/UHF yagis for mobile and on-foot RDF. Also makes active/offset attenuators for on-foot RDF and VHF/UHF RDF loop antennas. Reviewed in Homing In for August 1993 (yagis), July 1994 (resistive attenuator), April 2003 (loop) and Winter 2006 (active attenuator).
- APRS for DOS and
APRS for Windows/Mac/Linux -- Multi-purpose software for object tracking, RDF and much more. Interfaces with GPS and RDF sets. Links tracking sites via packet radio. Discussed in Homing In for October 1994, January 1995, February 1995, August 1995 and Summer 2007. DOS and Mac versions have the most RDF-related features. Unfortunately, PocketAPRS for Palm (which had excellent RDF support) is no longer available.
- BigRedBee LLC -- Greg Clark K7RKT sells the "BeeLine" 16-milliwatt microtransmitter for the 420-450 MHz ham band. Frequency, output power, dit rate and callsign are user-programmable. Reviewed in Homing In for Winter 2009.
- BMG Engineering, Inc. -- Former maker of "SuperDF" dual-antenna phase-front (TDOA) add-on for FM receivers. Reviews in Homing In for November 1989 and the T-Hunt book. Products are no longer available. Sales were suspended in October 1999. Web site is gone.
- Bob Miller Enterprises -- Bob Miller N6ZHZ sells fold-up 3-element RDF yagis for ham transmitter hunting (146.565 MHz) and ELT/EPIRB tracking (121.5 MHz). Reviewed in Homing In for Summer 2008. N6ZHZ is also a stateside reseller of the Sniffer4 RDF receiver for two meters and the aircraft band.
- Byonics -- Miniature PIC devices by N6BG, including the PicCon transmitter controller and Micro-Fox 15 miniature two-meter fox transmitter. Both can be used for both mobile T-hunts and synchronized MOE/MOI/MOS international foxhunts. PicCon was reviewed in Homing In for March 1997. Micro-Fox 15 was reviewed in Homing In for Summer 2011.
- Communications Specialists -- Spence Porter WA6TPR sells tiny low-power transmitters and sensitive receivers for the amateur 125 cm band (222-225 MHz). Reviewed in Homing In for Spring 2008. (Note that not all ham products are on the Com-Spec site at this time. If you don't see them, click on the link for "Radio Controlled Aircraft ELT System, High Power Long Range Amateur Radio version.")
- Cubex Quad Company -- Strung-wire VHF cubical quads for RDF. Reviewed in Homing In for February 1996 and plans for dual-polarization version are in February 1997 issue. Since publication, Cubex has changed owners and relocated to Florida. A second facility, Cubex ASC in Virginia, makes dual-band (2m and 70cm) quads for OSCAR satellite communications, also suitable for some RDF applications.
- Doppler Systems, Inc. -- Doppler RDF add-ons for FM receivers featuring patented smooth-transition switching. Reviewed in the T-Hunt book.
- Doppler DF Instruments -- Bob Simmons WB6EYV sells kits, including the PicoDopp, MiniAntenna, SquawkBox transmitter and Polar Plot for PDAs. SquawkBox reviewed in Homing In for Spring 2005. PicoDopp reviewed in Homing In for Winter 2012
- FAR Circuits -- Circuit boards for the Roanoke Doppler, Montreal Fox Controller, Doppler-to-RS232 Interface, 80-meter ARDF transmitter and many other home construction projects.
- Global TSCM Group -- Sells an almost-ready-to-use version of the WB6EYV PicoDopp complete with display enclosure, enclosed antenna switcher and four magnetic-mount whip bases. Also available is a GPS engine add-on and software for computer bearing display and tracking. Reviewed in Homing In for Spring 2012. Antenna base modifications for improved mobile performance are in this site.
- Hamtronics, Incorporated -- Supplier of ham radio kits, including low-power VHF/UHF transmitters suitable for foxboxes. T301-2Y synthesized exciter reviewed in Homing In for August 1998.
- Happy Flyers -- California organization that sold kits for an amplitude-comparison VHF RDF set for aircraft ELT location, as described in the T-Hunt book. This organization has disbanded and kits are no longer available.
- L-Tronics -- Long-time provider of "Little L-Per" RDF sets for airborne, vehicular and on-foot search/rescue. The original crystal-controlled L-per is no longer made nor sold by L-Tronics, but pre-owned units may be available from upgrading owners and factory service is available. Many hams have added appropriate crystals to original L-Pers for use on VHF and UHF Amateur Radio bands. A newly designed synthesized L-Per with wide frequency coverage became available from L-Tronics in January 2006.
- Marvin Johnston KE6HTS -- Supplier of kits and circuit boards for RDF projects including the KØOV Offset Attenuator, the WB6BYU 80-meter ARDF receiver-antenna set, the WB6EYV two-meter 50 mW "MicroHunt" ARDF transmitter, the WB2HOL tape measure two-meter Yagi, the KI6DYX yagi handle and receiver holder, and the WB6RDV turnstile antenna.
- Motron Electronics -- Software/hardware for "fingerprinting" and "signature analysis" of received signals. Reviewed in Homing In for November 1994.
- National RF, Incorporated (formerly Radio Engineers) -- Makes "Vector-Finder" hand-held phase-front (TDOA) add-on units for VHF ham radio and marine use, plus resistive attenuators and portable 2-meter quads. The Vector Finder was reviewed in Homing In for July 1996.
- North Olmsted Amateur Radio Development (NOARD) -- Supplier of kits for the HANDI-Finder®, a simple dual-antenna RDF add-on. See "Sense The Right Way To Go With The HANDI-Finder" at this site for performance improvements.
- OK2BWN Radio Sports Equipment -- ARDF transmitters and receivers for 80m and 2m bands by Jiri Maracek OK2BWN in Czech Republic.
- RAI Laboratories -- Bob Iannucci W6EI of RAI Laboratories is writer of the FoxHunt app for iPhone 3GS.
- Ramsey Electronics -- "SlyFox" transmitter and "Foxhound" phase-front (TDOA) add-on for FM receivers. Reviewed in Homing In for December 1993 and August 1994. See design improvements for these units at this Homing In site. Ramsey discontinued its kit line in early 2016, but some stock may still be available on Amazon.com.
- Rolcon RF Systems -- VHF and UHF yagi antennas covering many frequency ranges from 50 to 970 MHz.
- Ron Graham Electronics -- Former supplier of receivers and sniffing antennas for on-foot RDF on 80 and 2 meter bands by VK4BRG in Australia. Reviewed in Homing In for December 1997. No longer being sold.
- Sniffer4 -- Tiny synthesized two-meter and aircraft band receiver specifically designed for RDF on foot, sold by Bryan Ackerly VK3YNG in Australia. Reviewed in Homing In for Fall 2007.
- Swiech Communications Systems -- Rugged black-anodized VHF yagis for "stealthy" nighttime T-hunting.
Sophisticated RDF equipment and radiolocation systems and services are advertised by the following companies to the government and military markets, as well as to law enforcement and industry. As before, a listing does not imply my endorsement, or even the availability of actual products.
- Abaco Systems in Towcester, UK
- Alaris Antennas in Gauteng, South Africa
- Alion Science and Technology in McLean, VA
- Applied EM, Inc. in Hampton, VA
- Argon ST Corporation in Fairfax, VA
- ASC Signal Corporation in Garner, NC
- Astron Wireless Technologies in Sterling, VA
- Aventas, Inc. in Richardson, TX
- Berkeley Varitronics Systems in Metuchen, NJ
- CEA Technologies (Warrlock Direction Finding) in Canberra, Australia
- CFRS Spectrum Intelligence Systems in Cambridge, UK
- Chemring Technology Solutions in Romesy, Hampshire, UK
- Cobham PLC in Wimborne, Dorset, UK
- Cubic Corporation (formerly OAR) in San Diego, CA
- Cyntony Corporation in Lexington, MA
- DroneShield Ltd. in Sydney, Australia
- DRS ICAS, LLC in Merrimack, NH
- Electronics and Telecommunications Research Institute in Daejeon, Korea
- Elbit Systems in Haifa, Israel
- Israel Aerospace Industries, Elta subsidiary
- Fernau Avionics Limited in Bedfordshire, UK
- General Dynamics C4 Systems in Scottsdale, AZ
- Grintek Ewation (Pty) Ltd in Silverton, South Africa
- Granite Island Group near Boston, MA
- Grove Enterprises in Brasstown, NC
- Innovationszentrum fur Telekommunikationstechnik GmbH (IZT) in Erlangen, Germany
- Jenkins Engineering and Defence Systems, Ltd. in Matraville, NSW, Australia
- Koden Marine Electronics Products in Tokyo, Japan
- Leonardo Aerospace Company in Rome, Italy
- Link Microtek Ltd. UK in Hampshire, UK
- Mercury Systems, Inc. in Andover, MA
- Morcom International in Chantilly, VA
- NetworkFab Corporation in Santa Clara, CA, a subsidiary of Agilent Technologies
- NovAtel Hexagon Campus in Calgary, Alberta
- Praemittias Systems LLC in Chantilly, VA
- QinetiQ Ltd in Hampshire, UK
- Radio Reconnaissance Technologies in Stafford, VA
- Raven Research Ltd in Reading, UK
- RDF Products in Vancouver, WA
- RF Engines on Isle of Wight, United Kingdom
- RhoTheta Elektronik in Murnau, Germany
- Rockwell-Collins (Avionics) in Cedar Rapids, IA
- Rohde and Schwarz in Munich, Germany
- Roke Manor Research in Hampshire, UK, a division of Siemens
- Secez Services in Noida, India
- Servo Corporation of America in Westbury, NY
- Southwest Research Institute in San Antonio, TX
- Spectrum Signal Processing, Inc in Burnaby, BC, Canada
- Stratign FZCO in Dubai, UAE
- Summitek Instruments in Englewood, CO
- Synectics Surveillance Technology in Tewkesbury, England
- TechComm in Sunrise, FL
- Technology for Communications International (TCI), division of SPX, in Fremont, CA
- Techtest Limited, division of HR Smith Group in Kingsland, England
- Taiyo Musen Company in Tokyo, Japan
- Tecom Industries, Inc in Thousand Oaks, CA
- Telic AG (formerly Cellular Technology Engineering and Consulting) in Munich, Germany
- Thales Group in Gennevilliers, France and other locations
- Ticom Geomatics in Austin, Texas
- Titan Systems Corporation, Signal Products Division
- Tracking Products in the Denver area
- TriaSys Technologies in Billerica, MA
- Ventis Corporation in Carson City, NV
- Wildlife Drones in Canberra, Australia
- WiNRADiO Communications, division of Rosetta Laboratories, Oakleigh, Australia
Specialized transmitters and RDF tracking equipment for wildlife management (and sometimes for pet and human tracking) are advertised by these companies. Same disclaimer applies. For more on research uses of RDF, see Homing In for July 1995, January 2003, and Summer 2005. Also see the T-Hunt book.
- AVM Instrument Company in Colfax, CA
- Care Trak in Carbondale, IL
- Communications Specialists in Orange, CA, for wildlife, also for cats, for dogs, for model aircraft, and for law enforcement
- Environmental Studies in Goettingen, Germany
- Grintek Telecom in Centurion, South Africa
- Global Tracking Systems in Sylvan Lake, Alberta, Canada
- H.A.B.I.T. Research Ltd in Victoria, Canada
- Holohil Systems in Carp, Ontario, Canada
- Information Unlimited in Amherst, NH
- Locator Systems Corporation in Victoria, BC Canada
- Lotek Engineering in Newmarket, Ontario, Canada
- Magnum Telemetry in Grifton, NC
- Marshall Radio Telemetry in North Salt Lake City, UT
- Quick Track in Dothan, AL
- Sirtrack Limited in Havelock North, New Zealand
- Telonics in Mesa, AZ
- Televilt Positioning AB in Lindesberg, Sweden
- Titley Electronics in Ballina, Australia
- Tracker Radio Location Systems in Springdale, AR
- TracMe Beacons in Victoria, Australia
- Wildlife Materials, Incorporated in Carbondale,IL
- Wildlife Track Incorporated in Livermore, CA
RDF is an important tool for search and rescue. Here are some sites with information about it:
- ACR Electronics in Ft. Lauderdale, FL, makes Emergency Locator Beacons
- Artex Aircraft Supplies of Canby, OR, maker of Emergency Locator Transmitters (ELTs)
- Becker Avionics Systems of Rheinmünster, Germany, makes emergency beacons and airborne tracking sets
- Firestorm Emergency Services in Seattle, WA
- Front Range Electronic Direction Finders, Inc (Colorado), a search/rescue group
- L-Tronics in Santa Barbara, CA, makes well-known L-Per® RDF sets for tracking ELTs
- McMurdo in Portsmouth England, makes Emergency Locator Beacons
- Narco Avionics of Ft. Washington, PA, maker of ELTs
- Seimac in Bedford, Nova Scotia, Canada makes locator beacons and the ProFIND RDF set
- Tracker Locating Systems of Finland, maker of ELT tracking equipment
To list your site or become a Homing In Correspondent for your area, send e-mail to firstname.lastname@example.org.
Surfing suggestion: Is it necessary to build or buy a doppler set to be competitive on hidden transmitter hunts? Find out what southern California winners use in the Let's Go T-Hunting page.
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This page updated 2 June 2023