Fox hunt how-to
To find the fox, you need two pieces of information:
- Distance, or range (how far you are away from the fox)
- Direction, or bearing (which direction you should go)
Most modern radios, whether a mobile or a HT, have some form of a "bar scale" (modern "S" meter) to show you relative received signal strength. Generally one bar is a very poor signal and 4, 5 or more bars, depending on the radio, indicates a stronger signal. The closer you are to the fox, the stronger the signal will be. However, as you get closer to the fox, your S-meter will be "pegged" (at the maximum reading) and it will be of little use to you. You must find a way to attenuate (diminish or knock down) the received signal so that it registers again on your S-meter. Use one of the following methods to attenuate the signal. The last one can also be used to give you the direction to the fox.
- Tune slightly off frequency: The radio energy coming into your radio is greatest on the frequency of the fox. However, a transmitter emits a slight amount of energy outside the exact transmission frequency. By tuning slightly off frequency, your S-meter may be able to detect it.
- Remove the HT antenna: The antenna is designed to make reception more efficient. The worse your antenna, the lower your S-meter reading will be for a given signal strength. So if you remove your antenna altogether, your S-meter reading will go down dramatically. CAUTION: Make sure your transmit lock is on, so you don't inadvertently transmit without your antenna in place.
- Listen on a harmonic frequency: In addition to transmitting at the fundamental frequency, all transmitters also radiate at harmonic frequencies. The amount of energy radiated at the harmonic frequency is much less than at the fundamental frequency. So attenuate the signal by listening to the fox on one of its harmonic frequencies.
- Listen on a frequency that is 0.91 MHz less than the fox transmit frequency: Your HT receiver circuitry is designed to take incoming signals and boost their strength. Your HT's receiver most likely uses a superheterodyne design, which involves adding or subtracting signals generated in your HT to the received signal to produce an intermediate frequency, or IF. A standard IF is 455 kHz (0.455Mhz). You can receive the fox's transmission less efficiently in your HT if you subtract 2 times the IF (2 x 0.455 = 0.91 MHz) from the fox's transmit frequency
- Body Block: Use this technique to determine the direction to the fox. You can use an object that is dense enough to absorb enough of the incoming signal so that your S-meter reading falls. One object you always have with you is your body. Try holding the radio against your body and turning slowly. When your body is directly between you and the fox, the S-meter may drop (you may also hear the signal get weaker).
One thing you will probably notice the first time you go fox hunting is some people will be using directional antennas and even inline signal attenuators. These are good tools to make you better and faster but the basics discussed above when used correctly will lead you to the fox. If this is your first attempt at fox hunting do not concentrate on trying to be first. More importantly concentrate of finding the fox. Once you begin developing skills and your own methods, then and only then work on winning.
For additional information just do a Google search using some of the following key words; amateur radio fox hunting hidden transmitter.