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| Subject: | LF: Final results of 8.76kHz earth-mode tests today |
| From: | Roger Lapthorn <[email protected]> |
| Date: | Sun, 17 Jul 2011 18:54:41 +0100 |
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After lunch I did further tests at 8.7605kHz using long carriers interspersed with brief off periods for ID. Having had some success away from roadsides this morning I was hopeful of more "local" DX this afternoon. When I tried reception at a distance of 7km using one earth rod in Bottisham Lode (a fenland waterway) and one about 15m in from the water's edge in the soil no copy was achieved, even with SL in bandwidths of around 4.5mHz. Looking at the map it is not clear this waterway is directly connected to the watercourse I was using successfully this morning. Not to be beaten, I tried another reception test at a second location exactly 6km from the home QTH - this is 0.4km further than ever before. I tried to find the watercourse beside the road, but it was totally overgrown and inaccessible. So, instead I placed the 2 earth electrodes alongside the road (i.e. parallel to the road) in a line that would have been also parallel to the water in the water drainage ditch, if there. Using SL, with 11mHz settings as for the test before lunch, good copy was immediately achieved of the 5W test transmitter back at home. As before, I got my XYL to cut carrier for a 5 minute period (actually more like 8 mins as she forgot to turn it on again!) and the signal reappeared with the same thermal drift seen earlier. Also, I noticed that the signal was just visible with Spectran in 0.18Hz bandwidth. Results with a single turn loop on the ground and the 18m spaced earth-electrode pair were similar in S/N. I'm still not sure what orientation is optimum for either schemes. My new earth-mode DX is exactly 6km and my best yet. S/N in 11mHz was around 10dB, so there is more to be had yet, especially with more TX power (currently just 5W), better stability, moving down below 1kHz and even narrower SL bandwidths (currently 11mHz). With our 40th wedding anniversary and family commitments there will be a break in tests for a couple of weeks now, but I have lots of new things to try still. I assume no-one else was looking for my signal (or certainly no-one was successful) locally today? 73s Roger G3XBM -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm https://sites.google.com/site/sub9khz/
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