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Phase Linear 400 output transistors
On Sunday, June 1, 1997 3:00:00 AM UTC-4, John Whitmore wrote:
I've recently acquired a Phase Linear 400. This was an historically important audio amp, as it was the first of the wave of high-powered amplifiers that came out of the 1970's. This unit, though, has been through some tough times. I've found lots of shorted and fried components, but the main difficulty is in the output transistors. There are four different types plugged in to the sixteen TO-3 sockets. The outputs are four composite-Darlington transistors, each having a single driver feeding three paralleled output transistors. Someone in the past replaced some of the paralleled outputs with various types. So, I don't trust the types of transistors I see there. Also, I don't know what the original drivers were. Driver types: GE-37, DTS-701, RCA410 The first two are 700V, 1A; the third is 300V, 5A rated. Output types: GE-37, PL-909 The first is clearly inappropriate in this application, and the second is (apparently) a Fairchild special part number for Phase Linear. I assume it's intended to be a high current type, and possibly similar to 2N5264 (a Fairchild power transistor of the right era). From the emitter degeneration resistance (0.22 ohms) I suspect the output transistors should be roughly 5A rated. Does anyone know? Should I just jam in MJ15003's? Or maybe MJ410's (very similar to the RCA410)? And as for the drivers; should they all be the same type as the outputs? What were the original drivers? Thanks for any info; this can't interest many folk, so e-mail is preferred. John Whitmore If interested I have some XPL909 for sale |
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