The Wellbrook is a balanced amplifier, i.e. it floats the loop above
ground, and also isolates it from the feedline.

http://www.wellbrook.uk.com/ALA100b.html

Basically, you roll your own antenna. It just provides gain and the
differential input. Mine is an older version that is positive ground.
That is a total disaster if you use it near a car since if the hot
chassis hits the car body, the fuse zaps. I leave it on a zip lock bag
for isolation. I guess they changed the amplifier design to work better
with a negative ground. Normally you use the ALA100 with the wall wart,
but to use it in your car, you need one coaxial adapter than is
positive ground. Get this mixed up with another cable and you will
damage that device.

I'm going to try a more distant hill this week and see if I can get the
same accuracy.

Dave Bethke wrote:

<miso@sushi.com> wrote

The loop is untuned, so Q isn't an issue.

In that case it could be many things that cause the smaller loop to be more
accurate.  One more thing to think of - the feed line may be picking up some
signal causing inaccuracy or broader nulls.

But in any case, if you've been getting results from your tests that have
only 1 degree error you're doing extremely well.  Like many things, the
effort/expense to results scale is logarithmic.  :-)

.