|   |   |   | 
				  
				 Screened RF tetrode Introduced in 1929 (B4+sc, B5), 
				1930 (S4VA and S4VB) 
					
						| 1 | 2 | 3 | 4 | 5/sc | tc | base |  
						| g2 | f | f | g1 | k | a | B4/B5 |    
				
					
						|  | Vf | Af | Va | Vs | Vg | mAa | mAs | ra | gm |  
						| S4V | 4 | 1 | 200 | 75 | -1 | 1.5 |  | 910,000 | 1.1 |  
						| S4VA | 4 | 1 | 200 | 110 | -1.5 | 2.5 | 0.6 | 500,000 | 2 |  
						| S4VB | 4 | 1 | 200 | 110 | -1.5 | 4.6 | 1.05 | 300,000 | 2.5 |  
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