Trabem,

I will try to answer your remaining questions in the order at which
they occur.

There must be a compromise between size of loop, receiving
sensitivity, and the ability to rotate it. Only you can decide. I
can suggest only that you bias your opinion towards size matters more
than the ability to rotate the thing. Just make sure that the
broadside null does not correspond to the direction from which your
favourite transmissions come from. The receiving lobes in the polar
diagram are very broad. The polar diagram is a figure of 8, like a
pair of touching circles. You won't need Eznec.

The impedance of the line from the coupling loop to the receiver
doesn't matter two hoots. At 60 KHz it is just a pair of wires. A
twisted pair of wires has an impedance of very roughly 130 ohms.
But at 60 KHz the line length is so short in terms of wavelengths it
doesn't matter what its impedance is. The coupling loop can be
considered to be directly connected to the 50-ohm receiver.

And even with an extremely long line any impedance mismatch loss will
be negligible. So forget about 300-ohm balanced line and just use a
simple not-tightly-twisted pair. NO IMPEDANCE MATCHING REQUIRED at
either end. The size of the small coupling loop inside the main loop
matches 50 ohms to a 50-ohm receiver. So ideally the line to the
receiver could be 50-ohm coax. But, as I say, it doesn't matter.

The size and shape of the small coupling loop is not critical. It can
be circular or square. Theoretically, to match the loop to a 50-ohm
receiver, it should have an area about 1/25th of the main loop area.
To simplify construction the coupling loop can be made
self-supporting.

Electrically, the thickness of the wire in the coupling loop need be
no greater than the wire in the line which connects it to the
receiver. The only wire diameter which matters is that of the main
loop itself.

As the spacing between wires on the main loop increases the RF
proximity loss in the loop conductor (related to skin effect)
decreases and Q increases. But other things happen when the width of
the loop increases with spacing. For example, loop inductance
decreases. We are not comparing like with like. And in any case
maximisation of Q is not the primary objective. There are other things
to be considered.

For example, if you want to increase Q then don't bother to increase
spacing between turns, just increase wire diameter.

But with given wire diameter, the optimum spacing between the wire
centres of adjacent turns, to maximise Q, is very crudely about twice
the wire diameter. But, as I say, it is very non-critical and you
might be better off by increasing wire diameter as it simplifies loop
construction. Then, once again, you will have the option of
increasing spacing between turns. Compromises are never ending. ;o)

Whatever you end up with I can see from your enthusiasm you are
enjoying your efforts and will continue to do so.
----
Reg, G4FGQ.

=====================================

TRABEM wrote in message
...
Hi REg,

Looks like I have a plan for a new loop.

New loop design:

I have a plan for a more appropriately dimensioned loop.

At 60 KHz,

4 turns of 2 mm diameter wire, spaced 4 wire diameters apart.
2 meters per side
123 uH, 60,000 pF to resonate
4.7K across the loop.
300 ohm feed impedance at single turn loop feed
Q (unloaded) = 101

This allows me to feed the loop with 300 ohm balanced line, which I
can easily transform to 50 ohms at the receiver.

I'm not sure what the impedance of twisted wire is though, which
would
be even cheaper than 300 ohm twin lead.

Also, my Q will be slightly higher as I can stagger the turns some,
so
that the wires won't run parallel to each other for the entire
length.

I was never quite thrilled with a big loop threaded through the
trees
and supported in that manner, it makes it hard to rotate:: Being
able
to rotate the loop is a good thing::

Is the 1 turn pick up loop critical???

And, I have another question.......

I used rj2loop3 and ran the same numbers as above, except that I
separated the wires by 10 wire diameters instead of 4.

Instead of seeing the Q improve, it was reduced (from 101) to 93. I
expected the Q to improve, not get worse. It seems odd to me. Is
there
a good reason for this?? Ran it with a very low number and the Q
also
get worse. So there appears to be an 'optimal' wire winding pitch
for
optimizing Q?

Byr the way, nice software package, thank you for it's use!

I assume your QTH is not adjacent to WWV's antenna. ;o)

Temporarily, it is on the East Coast of the US. But, at home it is
high in the mountains in Northern EU (with no commercial power for
miles around).

Thanks,