Here's the LTSpice schematic for an amplifier chain that I've been building. (It might be hard to see, but maybe you can download it and look at a larger version.) Four stages, all feedback amps. The first three are class A, the final is Class AB. About 45 db total power gain -- it takes the .0001 watt (peak) from my balanced modulator and amplifies it to about 3.2 watts.
So far it seems very stable. Notice that I don't have any decoupling networks on the first three stages (other than a .1 uF cap to ground on the +13V supply rail. I tried to continue without decoupling on the final, but I got instability, so I added a 10 uH RF choke and a cap to ground as a decoupling network to the final stage. Instability disappeared. Do I need more decoupling on the other three stages?
The last two transistors are disgnated at 2N3053 and 2SC2075. That's what I'm actually using, but I haven't figured out how to get these parts into LTSpice, so I'm actually using 2N2222 models in my simulation.
Here is the actual LTSpice file: Bill's Kickpanel amplifiers
I'll talk about this project on SolderSmoke tomorrow. Comments welcome.
Linux Mint, QRP, & C / C++ Compilers
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Greetings:
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