High performance impedance transformation with the EFP-60 secondary-emission pentode

The unique characteristics of the EFP-60 secondary-emission pentode make it possible to utilize this tube in a novel cathode follower circuit in which the impedance transformation action is "enhanced" by connection of the secondary-emission dynode back to the cathode. An analysis of this circuit in two slightly different forms indicates the possibility of achieving cathode-follower action with virtually unity gain and consequently high input-to-output impedance transformation ratio. The results of the analysis are verified by experimental data. Some aspects of the circuit as applied to millimicrosecond pulse work are discussed, and conclusions are reached with respect to optimization of tube characteristics for this particular type of application.