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CREG Journal
Contents

A 20 Watt Linear Amplifier for VLF/LF Frequencies
Ian Drummond describes a power amplifier to increase the output power of the 2W LF CB transverter by a factor of ten thereby increasing the range by about 50%.

Back to Basics with Cave Communications (6-10)
What methods of cave communication are available? What are the pros and cons of each? When is cave communications useful? And where can I get equipment? Mike Bedford provides an introduction for the non-specialist.

Wet & Dry
The pros and cons of the various containers available for transporting electronic gear underground. Column edited by Richard Rushton.

MoleSpam - a Speaker Amplifier for the Molefone
The Molefone uses its microphone as a loudspeaker and has a limited volume. This add-on amplifier/speaker design by Chris Trayner is aimed mainly at Cave Rescue groups who operate Molefones.

Spatial Filtering as an aid to Signal Reception (15-16)
Radio amateurs reported the use of binaural processing to help recover weak CW signals from the interference many years ago. Jean-Jacques Fauchez, F6IDE, tried it out on 87kHz DSB. Translation by Rosy and John Rabson.

A Methodical Approach to Loop Antenna Design (17-20)
Loop antenna calculations are simplified by the use of a 'figure of merit' term, known as the 'effective aperture'. David Gibson explains how it is used.

Geological Maps - Uses and Limitations
Alan Clayton and Dave Beamish provide an introduction to the potential value of geological maps and their use with geophysical techniques that may help in optimising surface to underground cave radio communications.

Web Watch
Another wide-ranging review of electronic Web sites by Peter Ludwig.

Selected Further Reading
If you are interested in this issue's topics, this list of further reading from CREG journals, compiled by David Gibson, may be of use.

Cave Radio Notebook (24-25)
40: Interference Cancellation.

Flood Pulse Logging with PICs
Stuart France is adapting the PIC-based caver counter by adding serial memory and a water-depth sensor to research cave flood pulses.

Combating LORAN or 'Nobbling the Galloping Horses'
Interference from LORAN limits the range of cave radios. John Rabson has been trying out some counter measures and suggests some further approaches.

UP/CREG 1999 - Photographic Field Meet
Richard Rushton reports on the recent joint field meet.

Radio-location at Wakulla Springs, Florida
The use of radio-location equipment by diving expeditions as told to John & Rosy Rabson by Brian Pease.

Letters to the Editor
Feedback, debate, information & news - our readers have their say. Letters on Radio-location & Dowsing, Surveying Projects, Rescue Comms Meeting, Help Wanted.