GU43b 
Tetrode 
The GU43B tetrode is used for wideband power amplification at
frequencies up to 100 MHz in RF equipment. This tube is generally considered analogous to
the 4CX1000.

GENERAL  
Cathode: indirectly heated, oxidecoated.  
Envelope: metaltoglass.  
Cooling: 100 m^{3}/hour forced air.  
Height, mm, at most:  125 
Diameter, mm, at most:  101 
Mass, Kg, at most:  1.5 
C_{1}  grid 1; KP  cathode & heater; P  heater; C_{2}  grid 2; A  anode 

ENVIRONMENTAL OPERATING CONDITIONS  
Vibration loads: 

frequency, Hz  10200 
acceleration, m/s²  58 
Multiple impacts with acceleration, m/s²  342 
Ambient Conditions:  
Temperature, °C  60 to +150 
Relative humidity at up to +40 °C, %  98 
NOMINAL ELECTRICAL PARAMETERS  
Heater voltage, V  12.6 
Heater current, A  6.6 
Mutual conductance (V_{a} = 1KV, V_{g2} = 300V, I_{a} = 600mA, change in V_{g1} = 2.5V), mA/V:  45 
Anode current (I_{a}) with V_{a} = 3KV, V_{g1} = 50V, V_{g2} = 350V, A:  ~0.9 
Negative bias (V_{g1}) with V_{a} = 1KV, V_{g2} = 350V, I_{a} > 800mA, V:  2030 
input capacitance, pF  90 
output capacitance, at most, pF  14 
transfer capacitance, pF  <0.1 
Warm up time, s:  <180 
AB_{1} Output, V_{a} = 3KV, I_{a} ~0.9A, V_{g1} = 50V, V_{g2} = 350V, I_{g1} < 0mA, I_{g2} < 80mA, KW:  >1.6 
Designed Tube Life (hours)  >1000 
ELECTRICAL PARAMETER LIMITS  
Heater voltage, V  12.6 +/ ? 
Heater current, A  67.2 
input capacitance, pF  80100 
output capacitance, pF  1018 
Maximum CW Anode voltage (V_{a}), KV:  3.3 
"Maximum" Control Grid voltage (V_{g1}), V  200 
Maximum Screen Grid voltage (V_{g2}), V  500 
CW cathode current (I_{c}), A:  1 
Peak cathode current (I_{c}), A:  3.2 
Anode Dissipation, W:  1000 
Screen Grid (G2) Dissipation, W:  28 
Control Grid (G1) Dissipation, W:  5 
Temperature at envelope (hottest point), °C  150 
Frequency, MHz:  <100 
Averaged Anode Characteristic Cooling Curves: Anode T °C plotted against Airflow, m^{3}/sec vs P_{a} 
Averaged Anode Characteristic Curves: ^{___} . ^{___} . ^{___} P_{a} Dissipation: U_{f} = 12.6V; U_{g2} = 350V; 
Averaged Anode Characteristic Curves: U_{f} = 12.6V; U_{g2} = 350V 
Averaged Anode Characteristic Curves: U_{f} = 12.6V; U_{g2} = 350V 