LBARA - Fox Hunt Page

Just what is "Fox-Hunting", "T-Hunting", Transmitter-Hunting", or what ever you wish to call it, all about? It's part technical honest-to-gosh amateur radio, and part social. The object is to find a hidden Transmitter (the Fox) utilizing radio direction finding (DF) techniques. The Fox, also called a "hider". is responsible for concealing a transmitter and antenna in such a manner that it is confusing and difficult to find. The transmitter is keyed either continuously; keyed at regular intervals for a specified period, or keyed at random intervals for specified or random periods. The latter case obviously being the most difficult.
The Fox hunters (called the hounds) must all start from a common location from which the signal can be heard. Time limits for the hunt is specified prior to the start. Usually the hunters consist of teams of at least two, a driver and a navigator. The drivers job is obvious, to safely drive the vehicle. The navigator's task is to take bearings on the fox and to give directions to the driver.
Winners can be determined by a number of different methods, all of which are controversial in one manner or another. Least Mileage, shortest time, or a combination of both are possible methods. Actual methods used can be ironed out by committee action prior to the hunt.
The frequency used is normally 146.565 MHz or another selected simplex frequency. 146.565 MHz frequency is a common frequency in use throughout Southern California and many parts of Arizona as well as other parts of the Western U.S. Knowing this frequency you have time to research some DF antennas and either construct and tune an antenna(s) or at least gather up the necessary parts to build one.
There is a potpourri of DF antennas and techniques from which to select with Quad's and Yagi's being some of the most common antennas. Quad's and Yagi's properly tuned, provide ample gain and directivity for weak signals encountered at the beginning of a hunt. But when it gets to the final close-in phase of the hunt this same gain becomes a serious disadvantage.
To overcome this gain many DF'ers build a step attenuater that can provide up to 100db of attenuation in appropriate steps. An attenuater such as this can be built with a few pieces of double-sided printed circuit board material, eight (8) slide switches, a couple of BNC coax panel connectors, and 24 1/4 watt carbon resisters.
An accurate "S" meter is also a very handy accessory, if available, in this phase of the hunt.
Materials for antennas can be very simple: 1/2" PVC pipe and pipe fittings, wooden dowels, copper wire, a coax fitting, a small trimmer capacitor and a short length of coax. or you can go to exotic Doppler DF and TOA units either home-brewed or commercial.