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				HF tetrode 
				
				Introduced in 1927 
				
					
						
							| 1 | 
							2 | 
							3 | 
							4 | 
							tc | 
							base | 
						 
						
							| g2 | 
							f | 
							f | 
							g1 | 
							a | 
							B4 | 
						 
					 
					   
				
					
						| Vf | 
						Af | 
						Va | 
						Vs | 
						Vg | 
						mAa | 
						mAs | 
						ra | 
						gm | 
					 
					
						| 4 | 
						0.1 | 
						200 | 
						100 | 
						-1 | 
						4.5 | 
						0.8 | 
						400,000 | 
						0.9 | 
					 
				 
						B442 serie 100 is for 
						series feed 
						
							
								| Equivalent | 
								1915, A2004, C150, 
								DZ2, 
								H410D, 
								L409, PM13X, R81, RES024, RES094, RO4142, 
							S406, S410, 
								TB42, VH300 | 
							 
				 
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