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Representing years of collected experience in hidden transmitter searching and electronic design, we are pleased to make the FoxFinder™ RF sniffer available to the general fox hunting public. The FoxFinder was featured in a construction article in the April 2001 edition of QST; see the index of direction finding articles on the ARRL web site. The FoxFinder is shipped in kit form, for the moderately experienced builder. The kit contains all of the parts including silk-screened circuit board, detailed instructions with layout pictures, annotated diagrams, and drilling and cutting templates to assemble the unit. With user provided battery, antenna, and headphones the FoxFinder is a complete system. The typical use is with a three or four element two meter Yagi.
The original concept was just to ‘kit’ an existing design. This would make it easier for the typical hunter to add one to their toolkit. We built and tested several different circuits that had been published and evaluated the equipment in the field. Some of the designs were less sensitive than we desired and some failed based on ease of use in the field tests. One of the designs would not have been practical due to the cost of the components used. We then developed our own list of requirements including sensitivity, ease of use, user interface, and cost based on our experience and field trials. The end product of our research and development is a build-it yourself kit for a very compact field strength indicator with a wide dynamic range.
The FoxFinder is contained in a two and one-half by four and one-half by one-inch box that easily fits in a shirt pocket. The wide dynamic range across the 144 MHz ham band gives you enough sensitivity to detect a 300mw signal at 1000 feet yet not overload at two feet. It has only a power switch and a range switch for controls to make it easy to use. There are connectors for headphones and RF input from an antenna. An LED indicates that power is on; a 9-volt battery lasts approximately 50 hours. The signal strength indicator is an audio tone that varies in pitch with received signal strength. This is monitored using headphones plugged into the headphone jack. From usability testing we found that making adjustments and watching a meter or other indicator did not work well while you are navigating through the woods typical of where the fox boxes get placed so the operating controls were kept to a minimum.
The cost of the kit is $59.95 plus $5.00 shipping and handling in the U.S. To receive your kit, send your order with check or money order to FoxFinder c/o Ralph Swick, 113 Townsend Harbor Rd., Lunenburg MA 01462. Allow 4 to 6 weeks for delivery.
™ FoxFinder is a trademark of W1XP, KD1LE, and KD1SM.
2004-02-09