Class 2 Materials
This image of the Technician's band privileges is from Ham Radio Prep.
Class 2 Charts
For Inductors mounted in a circuit board. From: https://www.electricaltechnology.org/2022/01/inductor-color-codes.html
Variable Capacitor
From: https://www.elprocus.com/wp-content/uploads/construction-of-variable-capacitor.jpg
Class 3 Radio Wave Propagation
Tropospheric Ducting VHF and UHF.
From: https://vk3ph.net/wp-content/uploads/2022/10/Tropospheric-Ducting.png
HF Propagation types
From: https://www.qsl.net/4x4xm/Three_Propagation_Modes_c.png
Near vertical Incidence Skywave allows for communications for a short distance.
From:https://www.qsl.net/4x4xm/FAQ/What-is-NVIS-Propagation.htm