As you get closer to a transmitter the signal will get stronger, until it eventually tops out your 'S' meter. After that, as you get closer yet and the signal gets even stronger, you won't be able to see the difference on the meter. Now what? Well, this calls for some way to decrease the level of the signal arriving at the receiver so it can be kept within the range of the 'S' meter. While there are other methods you can use to knock down the signal strength (such as tuning slightly off frequency), the best way is to use an Attenuator in the coax cable between the antenna and the receiver. There are photos and diagrams of several types of home built attenuators in our Things to Build section. If you've got a sharp eye at hamfests, you might even find a commercially built step attenuator for less than $15.
Though
not absolutely required, another useful item is a Magnetic
Compass for determining direction. The compass, along with
a Protractor or other device
for drawing angles, can be used to determine and then indicate on a map
the direction from which a signal is coming. We'll briefly discuss this
when we talk about techniques.
One invaluable tool you shouldn't
be without is a Detailed Map
of the area in which you'll be hunting, especially if you're in unfamiliar
territory. In our area, maps covering a single county, such as those put
out by the HAGSTROM company, have proven indispensable. Some hunters cover
their maps with clear, adhesive-backed plastic so they can draw, and later
easily erase, their "signal bearing" lines without damaging the map.
If you cover your map this way, be sure to draw lines with a water-erasable
marker. Then you can later erase the lines with a dampened
paper towel. (Don't use the so called "dry erase" markers. They are easily
rubbed off... too easily, in fact. Plotted lines have been known to seemingly
disappear on their own as the map is moved around within the vehicle during
the heat of a chase! And, of course, don't use "permanent" markers or you'll
soon have yourself a spiderweb of lines recording a permanent history of
your earlier hunts.)
Continue to Hunting From Your Car - Basic Techniques
Hudson Valley Direction Finding Association
Copyright 1998,2003 John Hirth W2KI
All Rights reserved