I am currently using MJL1302/3281 in my 5 pair OPS, they have Cob of 600pF and my guess is the Ccb is proportionally higher also. I am seeing problem driving so many big transistors. I am considering to change them to 2SC5242 and 2SA1962. These are TO-3P a lower power transistors but with much lower Cob. My guess is the Ccb is proportionally lower.
I looked at the hfe vs current graph and they are comparable flat as the MJL. Since I use 5 pairs, I don't think I need to worry about SOA and hfe droop at high current as I am not pushing them at all. I use 5 pairs to lower the crossover distortion and get a bigger class A region.
My question is whether there is anything I need to look out. MJL are more popular for reasons that I might not aware of. So I want to hear from people here before I committed to buy 50 of each that is way over $100...More like $200!!
Also, when I crank the frequency to get 8Vpp pass 100KHz, the current increase gradually to over 2A pass 1MHz with no load. All the power is to drive the capacitance of those transistors. Cutting the Cob and Ccb will lower the power and less heat for the drivers.
Thanks
I looked at the hfe vs current graph and they are comparable flat as the MJL. Since I use 5 pairs, I don't think I need to worry about SOA and hfe droop at high current as I am not pushing them at all. I use 5 pairs to lower the crossover distortion and get a bigger class A region.
My question is whether there is anything I need to look out. MJL are more popular for reasons that I might not aware of. So I want to hear from people here before I committed to buy 50 of each that is way over $100...More like $200!!
Also, when I crank the frequency to get 8Vpp pass 100KHz, the current increase gradually to over 2A pass 1MHz with no load. All the power is to drive the capacitance of those transistors. Cutting the Cob and Ccb will lower the power and less heat for the drivers.
Thanks
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