TH558E power tetrode

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Product Overview



TH 558E is a ceramic-metal tetrode of coaxial structure, employing HypervapotronTM anode cooling, designed for use in AF and RF amplifiers up to 50 MHz. This tube brings high efficiency to medium- and short-wave transmitters. Moreover, the TH 558E s Pyrobloc grids result in highly stable operating characteristics. The anode cooling technique guarantees

enhanced safety margins with respect to the operating point.


The TH 558E delivers up to 550 kW, with a high gain and efficiency. This tetrode draws upon the proven technology in high-power AM radio tubes.




Electrical characteristics

Heater supply                                  23 V / 500 A

Amplification factor                          3.7 to 4.9

Transconductance (la = 10/15 A, VG2 = 1000 V)                                         

180 mA / V min.


Mechanical characteristics

Height                                             650 mm

Diameter                                         320 mm

Weight                                            74 kg approx.


Maximum ratings

Anode voltage                                 15 kV

Control-grid voltage                        1 000 V

Screen voltage                                1.25 kV

Peak cathode current                     600 A

Control-grid dissipation                   3 kW

Screen-grid dissipation                    8 kW




Typical operation SW

Output power (from PA)                  550 kW

Anode efficiency at 500 kW             83.5 %

Frequency                                      26 MHz

Heater voltage                                 20.5 V

Anode voltage                                 12.5 kV

Screen-grid dc voltage                    1 100 V

Control-grid dc voltage                    - 500 V

Anode dc current                            54 A

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