When your closing in on the fox you may find the signals to be strong enough you can no longer find a peak or null with your antenna.
Sometimes the signal is so strong that the RF will leak straight into the radio, connections and other equipment making the antenna useless.
The solution is to use an offset attenuator. The circuit consists of a small RF generator, in this case 4MHz, which will mix with the incoming fox signal (such as 146.52MHz) and produce new signals at plus and minus the fox signal (142.52Mhz and 150.52Mhz). A potentiometer on the board changes the injection level of the RF generator which in turn attenuates the incoming mixed signal to your radio to a level where tracking can continue.
Click here for more information on fox hunting and the offset attenuator.
Add a tape measure beam and you have a great club kit build project!
Schematics and build instructions can be downloaded here: FoxhuntV5C-Assembly