Bug nr. 1:
1.1) Obtain US handheld radio
1.2) Assign it to any possible quick slot (e.g., 5)
1.3) Equip that radio by pressing the number corresponding to the assigned slot
1.4) Use the "Turn on" / "Turn off" action - when the "Turn on" action is used, the knob will be animated to point at the "PWR OFF" position

Bug nr. 2:
2.1) Obtain US handheld radio
2.2) Assign it to any possible quick slot (e.g. 5)
2.3) Equip that radio by pressing the number corresponding to the assigned slot
2.4) Press [G] to open the radio radial menu
2.5) Hover over any of the transmitters on that radio
2.6) Press [R] to use the "Power switch" action - the radio will be turned off/on, but the knob will remain in its position.