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www.southgatearc.org
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Page last updated on:
Thursday, November 4, 2010
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UK Dreamer's Band first transmission (8.760kHz)On Wednesday, Nov 3, from 0915-1115 GMT, Roger G3XBM, transmitted a QRSS3 beacon signal on 8.760kHz under the terms of his recently-received NoV. He thinks this may be a first in the UK. TX was 4W from a TDA2002 audio IC matched into earth electrodes 20m apart. The beacon message (callsign and QTH locator in QRSS3) was provided by a K1EL keyer chip and the frequency reference was an HF crystal divided down by 512 times in a 4060 divider IC. Clear QRSS3 reception was possible 5.1km away from the transmitter location, detecting the signal with an 80cm loop fed into an E-field probe (Hi-Z input) into Spectran software. Marginal reception was just possible at 5.3km. Best reception was always with the loop flat on the ground suggesting the main mode of propagation is utilities assisted earth mode, as was the case at 838Hz back in the summer. Comparing results on 8.76kHz with those at 838Hz earlier in the summer in several locations from 1.5km out to 5.4km, my first impressions are that signal levels are at least 6dB weaker on 8.76kHz, but more careful tests will be needed. When I tried to look for any sign of radiated signals by aligning the loop vertically end-on to the TX location, no signals were detected although with QRSS3 and receiving in the bandwidth used this would have been very optimistic with 4W from the transmitter into earth electrodes. In the next couple of days I want to try the same set of tests using the 70m square vertical TX loop used on 500kHz and 136kHz. If my theory is correct and this is utilities assisted earth mode then I would expect results to be far worse with the loop as there will be less strong coupling into the ground. At some point in the near future I will do some extremely slow QRSS tests and let people know beforehand when the transmissions will take place. There is some remote chance that slightly more distant stations may be able to detect the signal although I have not been able to measure my frequency with the precision really needed yet. These tests are not at all in the same class as Stefan Schaefer DK7FC's experiments, but they are fun to do and I'm learning all the time. UK dreaming has started, if only modestly.
73s Roger G3XBM
G3XBM Videos G3XBM Blog G3XBM QRP Website Stefan Schaefer DK7FC - New 8.97kHz Amateur Radio DX record UK NoV's for Amateur Radio operation below 9 kHz
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