In a grounded grid amplifier using a triode vacuum tube, the plate is connected to a radio frequency choke. The other end of the radio frequency choke connects to the:

Vacuum tubes require a strong positive DC voltage on the plate (anode) to attract electrons from the cathode. This high voltage supply is commonly referred to as the B+ supply. However, because the plate is also where the amplified RF signal is generated, you must prevent this RF energy from traveling back into the DC power supply. To solve this, a radio frequency choke (RFC) is placed between the plate and the B+ supply. The RFC acts as an inductor that presents a very high impedance to the RF signals, keeping them in the amplifier circuit, while presenting very low resistance to the DC current, allowing the B+ voltage to easily reach the plate.