The Direction Finder is an amber terminal that tells you which way a signal comes from. It listens through Direction Finder Modules: stack 3 to 8 of them against the terminal or against each other, and run coax from the back of each to its own antenna.

Every module needs the same kind of antenna. A module with none, or a different one, shows a red lamp.

Each module's coax must reach one antenna and nothing else. Coax laid side by side joins up, and an antenna shared between two modules (or a module and a radio) is overdrawn and hears nothing.

Lay each run in its own dyed coax colour: coax joins only its own colour (plain is a colour of its own).

It needs power: run a power wire to the terminal, or to any of its modules (they pass it on), from a battery. Switch it on with POWER on the side panel; with no power the screen stays dark. Tune with the arrows or the scroll wheel (shift for ten steps), change band with up and down, or press F and type a frequency in MHz.

When someone transmits there, *RX* flashes and the modules lock one by one, about 2.5 seconds each. From three locked a compass needle shows the bearing, with its error.

More modules, a tighter bearing:

• 3 locked: about 10 degrees
• 4: 7
• 5: 5
• 6: 3.5
• 7: 2.5
• 8: 1.5

A signal arriving by skip is twice as rough, and a weak one half as rough again. After five quiet seconds the locks fall away, but the last bearing stays on screen.

Craft a direction finder with a World Map Module and its FIX page draws the fix on a map of the world instead of a grid. Journeyman cartographers sell the module for 12 emeralds and a compass.

One bearing gives a direction; two bearings from different places cross where the transmitter is. Press 2 (or TAB) for the FIX page.

Press A and type another station's X, Z, its bearing and its accuracy (enter alone means 5 degrees). Up to six can be typed in; D deletes the one selected.

The fix shows its X and Z, how many blocks it is good to, and its range and bearing from you. It needs:

• two bearings or more
• two stations at least 48 blocks apart
• bearings crossing at 15 degrees or more

Otherwise the page says why it cannot fix. Bearings at a wide angle give the smallest box.

A direction finder touching a microwave radio gets the bearings of direction finders at the other end of its link tuned to the same frequency, and adds them to the fix by itself (the L rows).

For walking in on a transmitter. Right click to set its frequency in MHz (it starts on 146.520). Hold it, in either hand, while a station transmits there: it beeps and blinks, from once a second facing away to ten a second pointed straight at it, higher and louder as you get closer.

It only hears by line of sight, never skip, and plays none of the station's audio.