On Mon, 26 Nov 2012 16:25:37 -0500, rickman wrote:

Just to give an update...

[...]

I did the calculations and at 100 uV/m with 50 foot of coax in a two
turn loop I get a bit over 1 uV, not so good. I'm going to see what I
can find about the signal level from ferrite cores. I had the
impression they would be lower, but I seem to recall better numbers than
this in the ones I've seen before.

Rick

When I was working with loop antennas, it became rather obvious that
optimal receiving loops too are 1 turn, with material of the largest practical
circumference. That one turn loop was coupled to one turn as the primary of a
coil / tuned transformer and on VLF / LF that concerned a potcore of the proper
material. The amount of turns for the secondary could be as much as 100 and
with a Q factor of 100 or more that meant at least 10,000 times the voltage of
the one turn loop - more than enough.

Jan