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.)
USA Radio-Orienteering Group (USA-ROG) in San Francisco Bay area
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 (ve7bfk-at-rac.ca), 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)
- Bozeman, MT via Harley Leach KI7XF (harley-at-ece.montana.edu)
- Portland, OR via Dale Hunt WB6BYU (wb6byu-at-arrl.net), ARDF Coordinator for IARU Region 2 (North and South America)
- Montreal, QC via Jacques Brodeur VE2EMM (ve2emm-at-qsl.net)
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).
Publishers
Some print and online publications with RDF-related content:
Equipment Suppliers
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.
- 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 resistive attenuators for mobile T-hunting, 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.
- BMG Engineering, Inc. -- Former maker of SuperDF dual-antenna phase-front (TDOA) add-on for FM receivers. Products are no longer available; sales were suspended in October 1999. Reviews in Homing In for November 1989 and the T-Hunt book.
- 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). To be 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. PicCon has modes for both mobile T-hunts and synchronized MOE/MOI/MOS international foxhunts. It was reviewed in Homing In for March 1997. Byonics also sells the DSP-RDF Doppler direction finder kit by Dan Welch W6DFW.
- 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 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.
- 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.
- 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 and the WB2HOL tape measure two-meter Yagi.
- 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 Depot (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.
- Optoelectronics -- Frequency counters and "bug busters" for sniffing signals on foot. Discussed in Homing In for July 1990; R20 reviewed in February 1994.
- 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.
- Rolcon RF Systems -- VHF and UHF yagi antennas covering many frequency ranges from 50 to 970 MHz.
- Ron Graham Electronics -- Receivers and sniffing antennas for on-foot RDF on 80 and 2 meter bands from VK4BRG in Australia. Reviewed in Homing In for December 1997.
- 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. An 80-meter ARDF receiver/antenna unit is also available from Bryan.
- Steven.Makes.It -- Circuit boards for the Roanoke Doppler. Also sells a clone of the the HANDI-Finder® (see NOARD above).
- Swiech Communications Systems -- Rugged black-anodized VHF yagis for "stealthy" nighttime T-hunting.
Also see my Hardware Sources page for links to suppliers of circuit boards, special parts, and complete kits for RDF-related home construction projects.
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.
- Astron Wireless Technologies in Sterling, VA
- Caravan International Corporation in Rio de Janeiro, Brazil
- CEA Technologies (Warrlock Direction Finding) in Canberra, Australia
- Cellular Technology Engineering and Consulting in Munich, Germany
- CSE Associates Incorporated in Walkersville, MD
- Cubic Corporation (formerly OAR) in San Diego, CA
- Direction Technology, Incorporated in Centreville, VA
- DRS Codem Systems in Merrimack, NH
- EDO Corporation (formerly Condor Systems) with headquarters in New York City
- Falcon-Protec PLC in Gloucestershire, England
- Fernau Avionics Limited in Bedfordshire, UK
- General Dynamics C4 Systems in Scottsdale, AZ
- Granite Island Group near Boston, MA
- Interferometrics Incorporated in Chantilly, VA
- Jenkins Engineering and Defence Systems, Ltd. in Matraville, NSW, Australia
- L3 Communications in New York City
- QinetiQ Ltd in Hampshire, UK
- Monteria LLC in Mt Airy, MD
- NetworkFab Corporation in Santa Clara, CA
- Poynting Antennas Ltd in Wendywood, South Africa
- Radio Reconnaissance Technologies in Stafford, VA
- RDF Products in Vancouver, WA
- RF Engines on Isle of Wight, United Kingdom
- Rockwell-Collins (Avionics) in Cedar Rapids, IA
- Rohde and Schwarz in Munich, Germany
- Servo Corporation of America in Westbury, NY
- Southwest Research Institute in San Antonio, TX
- Spectrum Signal Processing, Inc in Burnaby, BC, Canada
- Summitek Instruments in Englewood, CO
- Synectics Surveillance Technology in Tewkesbury, England
- Technology for Communications International (TCI) in Sunnyvale, CA
- Taiyo Musen Company in Tokyo, Japan
- Tecom Industries, Inc in Thousand Oaks, CA
- Thales Communications in Gennevilliers, France
- Titan Systems Corporation, Signal Products Division
- Tracking Products in the Denver area
- WiNRADiO Communications, division of Rosetta Laboratories, Oakleigh, Australia
- Zeta, a unit of Integrated Defense Technologies in San Jose, CA
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
- 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 k0ov@homingin.com.
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 at my Let's Go T-Hunting page.
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This page updated 27 June 2008