Frequency selective amplifier methods and circuits

Claim 1

A FREQUENCY SELECTIVE DEGENERATIVE AMPLIFIER SYSTEM COMPRISING THE COMBINATION OF ONE PENTODE HAVING A FIRST ANODE, A FIRST CATHODE AND A FIRST CONTROL GRID; RESISTANCE MEANS COUPLED BETWEEN SAID ANODE AND A SUPPLY VOLTAGE; MEANS BIASING SAID PENTODE FOR OPERATION FREE OF OSCILLATIONS; A FIRST TRIODE HAVING A SECOND ANODE, A SECOND CATHODE AND A SECOND CONTROL GRID, SAID SECOND CONTROL GRID BEING COUPLED TO SAID FIRST ANODE, SAID SECOND CATHODE BEING COUPLED WITH ELECTRICAL GROUND BY AN IMPEDANCE MEANS, SAID SECOND ANODE BEING COUPLED WITH A SUPPLY VOLTAGE, SAID FIRST TRIODE AND THE IMPEDANCE MEANS COUPLED TO THE CATHODE THEREOF OPERATING AS A FIRST CATHODE FOLLOWER STAGE; SAID FIRST CATHODE FOLLOWER STAGE PROVIDING A LOW A.C. IMPEDANCE OUTPUT PATH FOR SIGNALS AMPLIFIED BY SAID PENTODE AND A HIGH IMPEDANCE LOAD FOR SAID PENTODE; FILTER MEANS HAVING A FIRST INPUT CONNECTION COUPLED TO SAID OUTPUT PATH AND AN OUTPUT CONNECTION COUPLED TO SAID FIRST CONTROL GRID, SAID FILTER MEANS INCLUDING MEANS COUPLED BETWEEN SAID FIRST INPUT CONNECTION AND SAID OUTPUT CONNECTION FOR PASSING SUBSTANTIALLY ALL BUT SUBSTANTIALLY ONLY ONE FREQUENCY, SAID FILTER MEANS ALSO HAVING A SECOND INPUT CONNECTION AND INCLUDING MEANS COUPLED BETWEEN SAID SECOND INPUT CONNECTION AND SAID OUTPUT CONNECTION FOR PASSING SUBSTANTIALLY ONLY SAID ONE FREQUENCY, AND A SECOND SINGLE TRIODE CATHODE FOLLOWER STAGE FORMING THE INPUT NETWORK OF SAID SYSTEM, THE OUTPUT TERMINAL OF SAID SECOND CATHODE FOLLOWER STAGE BEING CONNECTED TO SAID SECOND INPUT CONNECTION; SAID FIRST CATHODE FOLLOWER STAGE, SAID SECOND CATHODE FOLLOWER STAGE AND SAID PENTODE BEING ALL ADAPTED TO ALL BE OPERATED FROM A SINGLE POWER SUPPLY MEANS HAVING ONLY POSITIVE POTENTIAL WITH RESPECT TO SAID ELECTRICAL GROUND, SAID PENTODE COMPRISING THE ONLY AMPLIFYING STAGE OF SAID SYSTEM HAVING A GAIN GREATER THAN UNITY, SAID OUTPUT TERMINAL OF SAID SECOND CATHODE FOLLOWER STAGE AND SAID SECOND INPUT CONNECTION BEING AT THE SAME POTENTIAL.