Spin wrote:
Is it feasable to remove the ferrite antenna from an am radio & replace it
with an external multi-turn box loop with the same primary/secondary
inductance?

Most of those internal ferrite antennas that I have
seen are transformers or autotransformers for
impedance matching. It would be hard to couple an
external air core transformer as efficiently as
is possible with ferrite.
--
73, Cecil http://www.w5dxp.com