Some unknown models of ferrite cores in hand should indeed be screened. At the very least, it is necessary to determine whether they can be used in the shortwave band. (Some were salvaged from broken computer power supplies.) Prepare the components.
Arrange the layout of several components on the perfboard.
Soldering.
Take out two unknown models of ferrite cores and test whether the circuit has any issues.
The circuit is normal. The white ferrite core cannot be used in the shortwave band. The black ferrite core should work in a certain band.
Components, assemble.