A novel gun double hop gun of rf power amplifier based on an always-on ringed cold cathode is suggested. Double hopping electron funnels, including a metal funnel and a glass funnel, are fabricated in. MgO film is deposited around the walls of the funnels by electron beam evaporation. Secondary electrons or backscatters (elastic and inelastic) escape from the dielectric film (MgO) under the bombardment of accelerated electrons and are driven to the exit window of the glass funnel by a modulated voltage. Among the escaping electrons, the ratios of secondary emission electrons, elastic scatters, and inelastic scatters are 90%, 9%, and 1%, respectively. Most of the escaping electrons at the exit window have low energy (< 50 eV) and can be easily controlled by the modulated voltage with low amplitude (similar to 100 V) applied on the electrode of the glass funnel. The average velocity in the Z direction of the escaping electrons increases as the amplitude of the modulated voltage (V-gate) increases. The distributions of the velocities in the X and Y directions are found to be symmetrical. (c) 2007 American Vacuum Society.