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On Sat, 6 Jan 2007 20:35:49 -0500, "Jimmie D"
wrote in : "Frank Gilliland" wrote in message news ![]() On Sat, 6 Jan 2007 15:40:50 -0500, "Jimmie D" wrote in : snip Two transistors in paralell only have the gain as one. His transistors are in push-pull, not parallel. Same thing no more gain. One would have to be driving the other to have any more gain, It will just handle more power. I rushed the last answer because I was in a hurry to get out the door. Anyway, your statement is true if you are talking only about current gain. Power gain, OTOH, is double in either configuration. For example, if a transistor with a current gain of 10 is fed an input of 100mA the output will be 1A. Two transistors in parallel will split the input current at 50mA each, with an output of 500mA each or 1A total. No additional current gain. But you are forgetting that when two transistors are in parallel the input and output impedances are reduced by half. If you take the input signal and convert its impedance to one-fourth of what is fed to a single transistor you can maintain 100mA input to each transistor using the same input power, with an output having -twice- the current at half the impedance of one transistor. The result is double the power gain. Brian's amp should be pushing 18dB. If it isn't then he screwed up the matching of the transistor input and output impedances. That's one reason why I want to see his schematic. |
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