GU61 B
TETRODE
The GU61 B tetrode is used for RF power amplification at frequencies up to 70 MHz
GENERAL
Cathode: directly heated, carbonized thoriated tungsten
Envelope: metalceramic with ring leads of
cathode and grids.
Cooling: forced air.
Height: at most 330 mm.
Diameter: at most 204 mm.
Mass: at most 18 kg
K1, K2  cathode; C1  grid 1; C2  grid 2; A  anode; I  contact surfaces
OPERATING ENVIRONMENTAL CONDITIONS  
Lowest permissible ambient temperature, °C  60 
Relative humidity at up to +40 °C,%  9598 
BASIC DATA Electrical Parameters 

Filament voltage (AC or DC), V  6.3  
Filament current, A  121141  
Resistance of unheated cathode, Om  0.005  
Anode current, A, at least  5  
Grid 2 current (at anode voltage 2 kV, grid 2 voltage 1 kV, anode current 5 A), A, at most 
0.7  
Negative grid 1 cutoff voltage (at anode voltage 10 kV, grid 2 voltage 1.5 kV, anode current 0.1 A), V, at most  330  
Mutual conductance (at anode voltage 2 kV, grid 2 voltage 1.25 kV, anode currents 5 and 7 A), mA/V  6385  
Gain coefficient (grid 1grid 2) (at anode voltage 2 kV, grid 2 voltages 1.25 and 1 kV, anode current 5 A)  79  
Oscillatory power (at 70 MHz), kW  30  
Interelectrode capacitance, pF:  

Limit Operating Values  
Filament voltage (AC or DC), V  7.98.7 
Filament starting current, A  190 
Anode voltage (DC), kV  10 
Grid 2 voltage (DC), kV  1.5 
Dissipation, kW:  
anode  25 
grid 2  0.7 
grid 1  0.3 
Operating frequency at oscillator power output 30 kW, MHz  70 
Temperature at stem and metaltoceramic seals, °C  175 
Anode temperature, °C  250 
Averaged Anode Characteristic Curves:
U_{f} = 8.3V; U_{g2} = 1.5kV
Averaged Characteristic Curves:
U_{f} = 8.3V; U_{g2} = 1.5kV;
_____ grid 1anode;
_ _ _ grid 2anode
Averaged AnodeGrid Characteristic Curves:
U_{f} = 8.3V; U_{g2} = 1.5kV
Averaged Grid 1 Characteristic Curves:
U_{f} = 8.3V; U_{g2} = 1.5kV
Averaged Grid 2 Characteristic Curves:
U_{f} = 8.3V; U_{g2} = 1.5kV