Vacuum tube construction takes several forms. Of these, the simplest is two plates separated by a grid wire. The grid can be biased by the application of voltage to increase, decrease or halt the flow of these ions to the upper plate. Other forms include more plates with more grids to allow better control of the ion flow. By proper biasing, vacuum tubes can be operated as switches, modulators or amplifiers among other uses.
Vacuum tubes operate primarily with high voltages that control the ion flows.
So if the circuit is 6 vacuum tubes in parallel, all fed from a common antenna, outputting to a common load terminal, then the common antenna input would feed all vacuum tubes with the same wave. Keep in mind that electricity is much like air or water. That is PSI is pressure, CFM is flow. Another analog is comparing a river to electricity. Fuses function on just this principle, when the current flows over the surface of the fuse, it creates heat.