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						| Mullard SP4/5 box |  | 
				 Pentode Introduced in 1932 
					
						| 1 | 2 | 3 | 4 | 5 | tc | base |  
						| f | g2 | f | g1 | k | a | B5 |    
				
					
						| Vf | Af | Va | Vs | Vg | mAa | mAs | ra | gm |  
						| 4 | 1 | 200 | 100 | -2 | 3 | 1.1 | 2,200,000 | 2.3 |    
					
						| Equivalent | 4636, ARP6, CV1324, CV1468,
						E446, H4128D,
						HP4100, HP4101, 
						MSP4,
						RENS1284, RS4346, ST4110, 
						T4600, TE46, 
						WE23 |  |  |  |