In article ,
Tom Bruhns wrote:
As has been pointed out in other postings to the thread, the
coefficient of coupling is important. Whatever flux from the
primary (driven winding) does not couple to the secondary will
not induce voltage in the secondary, and the measured turns ratio
will be low as a result. However, by measuring the inductance of
the primary when the secondary is open and again when it is
shorted, and doing the same with the secondary, you can find the
leakage inductances and therefore the coefficient of coupling,
fairly accurately.

That method of measuring the leakage inductance
(by shorting windings) gives a hint towards a
possible experimental method.... Short the sec
with an ammeter and treat the thing as a CT.

After all, CT's have a current-ratio that is quite
close to the turns-ratio, even though the coupling
can be poor (as in a CT with a bar primary). This
is because the leakage inductance (and R-primary)
can be regarded as being in series with a constant
current stimulus source. The major source of error
is then the sideways current due to the shunt loss.

So perhaps do a short-circuit current-ratio test,
then measure the sideways shunt-current taken by
just the primary, at the same equivalent voltage.

--
Tony Williams.