15 JUL 2014
WYLYE VALLEY 1914 PROJECT
Wylye Valley 1914 Project - a commemorative weekend organised by a sub group of the Codford local history society.
The event takes place over the weekend of 26/27 July 2014.
Several members of our club are working with Rod G4ZUP to set up a working demonstration of an earth mode telegraph system.
A website for the EMT has been set up courtesy of Dave G3ZXX (GB3JB keeper), see http://earthmodetelegraph.webnode.com/
Some of the site is still under construction.
In essence the group plan to communicate CW messages through the ground over by injecting at 1kHz audio tone. The tone being generated by a Velleman kit oscillator board, will be fed in to a Velleman mono audio amp. The output then fed to a solid state commercial music amp (Power edge). The output then fed to two earth rods approximately set 30 metres apart. The receiver (another kit built board) comprises a preamp and 7 watt audio amplifier driving a speaker or headphones. All power derived from batteries. The receiver is connected to a similar pair of earth rods (aerial).
Test have all ready proved successful at a nearby test site, when an audible signal was sent and received over a distance of around 160 metres. This was despite an impedance mismatch. The tx power was measured at 11 watts. The ground resistance at the test site is around 40 ohm between rods.
CW operators are sought to assist over the weekend (see the above link). Please contact T&DARC if you can help. There is a feed back form on the EMT website.
The event bodes to be an enlightening weekend for those interested in the history of the area during the Great War.