Jim Lux wrote in
:

Mouser has them.. Don't know if they ship in VK land or not.

Yes, but shipping anything from them and some other big suppliers is
prohibitive.

Shipping of what is basically iron bars is going to be punitive.
FairRite has distribution there (Specialised Conductives in Victoria),
but perhaps not retail. But, since one typically isn't looking to buy
just one, but dozens, this might not be a problem.

For some reason, magnetics ex USA through Aussie distributors / retailers
are outrageously expensive. Typically on Ebay one can buy 10 cores ex USA
for the price of one from a Aussie retailer.

One should be careful about modeling these things.. that gets you
close, but parasitics are a real bugabear. K9YC's paper has actual

Yes, agreed. I have made measurements of a number of choke
configurations, albeit only with a TAPR VNA (hate the software), and
calibrated my models to the measured values. It is certainly a balancing
act to put enough turns on a toroid to get high Z, but few enough turns
that Z hasn't gone seriously south at the top end of the desired range.

Predicting magnetics behaviour is a bit of a black art, but models help
to guide one to a better understanding of behaviour.

It is little wonder than balun specifications, where they are given, bear
little relation to the intended application.

Owen