Cross Reference Please: NPN TO66 Case Transistor

Apparently made by Signetics, marked as follows:

AMP2947

6808

I find no cross for it in my ECG book, can't find a direct reference on-line. This is the driver transistor for a vintage-1971 AR integrated amplifier. The outputs are 2N3055s.

Their schematic lists in parenthesis (2N3054) which physically fits, but gives quite a distorted output. I matched two 2N3054s with very low leakage and matching Beta, got distortion. I used two "stock" transistors from another amp, worked just fine. Which, by the way, closely match on my tester the parameters of the 2N3054s... go figure.

Thoughts? Ideas?

Thanks in advance.

Peter Wieck Wyncote, PA

Reply to
pfjw
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if signetics then presumably 1968 , could it be Ge ?

Reply to
N Cook

Nope, all silicon per AR.

Once upon a time a while back, Mouser crossed this to the 2N3054, which worked for me in some examples of this amp. But not this example. One person in another NG suggested that newer-run transistors are "faster" than older ones - perhaps I should add some small resistance - I will try that tonight.

I think I may have a very-early-run AR amp so, we shall see.

Peter Wieck Wyncote, PA

Reply to
pfjw

Thanks all for your ideas and responses. I did get a lead to a former AR Employee, Alex Barsotti who works now for AB Technical Services in Worcester, MA. He happens to have the exact replacements in-stock, can't ask for any better. Yes, there are some differences between it and the 2N3054, such that the more common unit *will* work some of the time, but not all of the time.

I will try the added resistor trick before changing out those that are in there now, but as they are on sockets, even a change-out is the work of a few moments.

Thank you, Bruce, Roy and finally Alex for getting involved in this tiny little request.

Peter Wieck Wyncote, PA

Reply to
pfjw

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