160 metre DF Equipment

Competitors

Receiver

This is a simple tuneable receiver with a directional aerial and a sense aerial. The aerial is either a ferrite rod or a loop. The sense aerial is a telescopic whip. The receiver has a BFO (Beat Frequency Oscillator) so that morse signals can be easily heard; this makes a signal with no speech on it sound like a whistle.

The receiver has controls for:

Audio gain (volume)
RF gain
Main tuning
Antenna tuning
BFO on/off
Sense on/off
Main on/off

Headphones

Headphones are used to keep out background noise making weak signals easier to hear.

Compass

These vary considerably and can be used in different ways.

Walking compass. A Silva, or similar make, walking compass fixed to the receiver (away from any magnetic materials including a ferrite rod). The receiver is held in the null position and the bezel of the compass aligned with the needle. The bearing is read off the bezel.

Sighting compass. The receiver is held in the null position at arm's length or on the ground; the compass is held in line with it and sighted along the line of the receiver. The bearing is read directly from the compass.

Monitor Receiver

This is a receiver fixed in the car and used to monitor the transmitter frequencies. Many scan the frequencies automatically. it must be connected to a non-directional receiver.

Map

A 1:50,000 Ordnance Survey map of the area. All the transmitters and the start will be on one map (or an area equal to one map with the boundaries published in advance).

Plotting Equipment

Protractor
Straight Edge
Pencil

Clock Card

A card for use in the transmitting station DF clock

Transmitting Stations

Transmitter

The type of transmitter most commonly used is one designed by Phil Arnold (G4CFG) and Norman Rathbone (G4KZU). Its main features are:

contained in an ex-army ammunition box measuring 300 x 185 x 155 mm including the battery and microphone
crystal controlled frequency
about 10 watts RF output
amplitude modulated
built-in aerial tuning unit
automatic morse generator

DF Clock

A specially designed clock which records the times when the competitor's clock card is inserted. This was designed by Phil Arnold (G4CFG). Its features are:

Self contained
Continuous display of time to 1 second
Records and displays card number and time of first insertion of a competitor's card
When a special card is inserted it displays the entry number, card number and time of all inserted cards (so that the transmitter operator can keep a paper back-up copy)
Serial port for uploading the recorded information to a computer

Contest Organiser

Computer

To upload information from DF Clocks

Printer

To print the results

Lots of Wire

For aerials

Tools to get the Wire High into Trees

For example: pole, weights, fishing rod and reel