LF: Grabber: Antenna and Upload Problems

[MarkusVester@aol.com]

Dear LF screen grabber users,

some of you may have noticed a change in the appearence of the screenshots at 
http://members.aol.com/df6nm/Grabber.htm . For reasons of lightning safety, I do not dare to continuously leave my transmit antenna up above our house during the summer months. Instead, I have strung a thin piece of wire halfway up a tree as a passive, receive only E-field probe, located in a corner of the garden near the H-field loops. It is series-resonated by ~12 mH, coupled to the 50 ohm receiver cable via a 3:1 isolation transformer, and grounded to the nearby wire-mesh fence.

Unfortunately performance is not quite up to the old standards because, like the loops, it receives a lot of SMPS noises from the neighbours. I searched for the source of the noise but couldn't locate anything like a radiating buried cable. My hypothesis is now that the noise may actually be carried by distributed conduction currents in the ground, which are fed from the power grid through the separate earth connections of the neighbouring houses.

Another effect which was sort of expected is that the "summer antenna" is much more sensitive to moisture; when it is raining the colour of SXV goes from orange to greenish. I hope to improve that by using even stronger overcoupling, i.e. going to a higher load impedance than 450 ohms.

After many months of successful operation, since about three weeks ago, at least one of the three hourly updates fails due to some ftp problem at members.aol.com. Up to now, neither AOL's email helpdesk nor their telephone hotline could be bothered to fix or even analyze the problem. There seemed to be a couple of times when my site couldn't be reached for http downloads either. If you are experiencing persistent problems accessing the grabber, please report by email to me directly.

73 and have a good time

Markus, DF6NM