INSTALLATION AND OPERATION

Installation of the antenna requires a little forethought and common sense. Never use "bungie cords" to anchor the antenna... wind forces acting on the antenna at freeway speeds require something stronger.

The author has used nylon "cargo straps", available at auto parts stores.... the straps were routed through the passenger compartment, ( the windows were slightly opened ) and over the rooftop, where the antenna was located. To prevent scratching of automobile paint, a buffer of some sort must be placed between the antenna underside and the top of the vehicle... tennis balls installed at each corner, a blanket, etc.

Once the unit is constructed, hook-up is fairly simple. Donít calibrate the unit with a repeater signal... there is too much chance that the signal is reaching the D/F by reflecting off of some object or structure which will make the bearing unknown. Use a handheld unit, operated by a friend, and walk it around the vehicle, observing the D/F display as it proceeds. It is best to do this in a clear area, like an open field or a large, empty parking lot, to minimise reflections from nearby objects.

An annoying "whine" should be obvious in the received audio, which is caused by the Doppler pulses. There is only one internal adjustment, and that is the calibration pot, which ( obviously ) is "tweaked" until the indicated bearing is correct. The calibration adjustment has a range of over 360 degrees.

It is important to remember that the antennas are connected to diodes, so it is not safe to transmit while the D/F antenna is connected.... the diodes can be vaporized in a fraction of a second. If the microphone can be disconnected, this is a good idea, to prevent accidental "reflex" transmissions that might occur during the chaos, excitement and confusion of a T-hunt.


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