john devoldere, ON4UN wrote: > Can anyone help me with the input impedance of the 3cx3000a7 tube (used on > HF). I require this value to build a proper Pi- filter input circuit. The datasheet I have gives values between 46 and 50 ohms for different conditions from 4 to 4.8kV, 300-400W drive and 6-7 kW out. Steve