If you are building radios etc. I recommend a
couple pieces of test equipment:
Elecraft XG3 S9
generator and more.
Meter IIB for measuring inductance and capacitance.
Ferrite beads and toroidal cores good information
Ferrite & Iron Powder Toroid Info another good reference
PL-259 coaxial cable
FSK/CW interface for my IC-7600 and other radios