GU-138A Печать


GU-138А and GU-138B


Ceramic/metal tetrodes with oxide-coated indirectly heated cathode with air forced (GU-138B) and water forced (GU-138A) plate cooling with plate dissipation of 10 kW intended for use in wideband output stages of HF and VHF broadcasting equipment as well as for SSB linear amplifiers.


General characteristics



Heater voltage 27 V

Heater current at 24 V 11 А

Cathode - oxide-coated indirectly heated

Current 20 А

at Ua=0,6 kV, Ug2=450 V, Ug1= 0 V

Interelectrode capacitances (cathode grounded):

Input 300 pF

Output 43 pF

Feadback 1,3 pF

Maximum frequency 100 МHz


Maximum dimensions:


Height 220 mm

Diameter 112,6 mm

Weight 5 kg


Height 170 mm

Diameter 176 mm

Weight 5 kg



- platewater forced

- other elements of envelope – air forced

Maximum tempereture of envelope 180о С

GU-138Bair forced

Maximum temperature of envelope 220о С


Maximum ratings


DC plate voltage 3,5 kV

DC screen voltage 475 V

DC grid voltage, negative 200 V

DC cathode current 9 А

Plate dissipation 10 kW

Screen dissipation 150 W

Grid dissipation 3 W


RF power amplifier (class В)


Frequency 75 МHz

Heater voltage 27 V

DC plate voltage 3,5 kV

DC screen voltage 450 V

DC grid voltage, negative 104 V

DC plate current 6,4 А

DC screen current 230 mА

Output power 14 kW





SSB power amplifier (class АВ1)


Frequency 100 МHz

Heater voltage 27 V

DC plate voltage 3,4 kV

DC screen voltage 350 V

Plate current at working point 2,8 А

DC plate current 4,8 А

DC screen current 130 mА

Output power 7,5 kW

Intermodulation distortion of 3-rd and 5-th orders minus 35 dB