john sexton said:
Our experiences seem to confirm that this sort of size (i.e. of the order
a couple of metres in diameter) and particularly the use of low resistance
Litz is optimum.
The number of turns is 10 in Peter's case and 36 in mine and I am still
unsure whether more or less is better...
I confess to not having searched for an optimum L/C ratio;
I just aimed for what seemed a reasonable LC ratio. The weight of the wire
inside the loop enclosure was also a consideration.
Peter suggests that multistranded PVC covered wire would be a good
substitute where Litz is not available. I cannot agree with this - I first
wound my loop with this type of wire and was very disappointed with the
If only thin insulated wire were available then the PA0SE type construction
would be best.(page 13 of LF handbook) to reduce the loop self capacity.
The PVC pipe construction would need a wire diameter of at least 1mm with an
insulation thickness greater than .5mm. Even so, it would not be as good as
As regards noise, I find a sensitive loop is very susceptible to magnetic
QRM (as you might expect) and it has to be sited as far from the house as
possible to avoid TV or computer monitor QRM.
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