Patrice, I assume you are "fast_logger", as identified by Kevin.

To have any effect, a ferrite (or air-loop) with LW or MW winding must either

1. be hardwired into the PL380 in lieu of the internal one, in which
case the internal MOS "varactor" will tune it, or

2. be tuned with an external parallel variable capacitor for induction
coupling to the internal ferrite antenna. This can work well, but can be
temperamental and require patience with tuning and spacing from
the internal ferrite winding. See other recent postings.

Steves series/parallel option looks very promising. I dont have any litz
for a tailored winding, but will try the idea with cannibalised windings like yours.

Michael UK
"Suck-it-and-see-Labs Inc."