I suspect that ArnoR has not yet tested an original LZ1AQ amplifier and he did not evaluate it's performance on the bench nor in the field. Some of his judgement seems to be based on simulations and his assumptions, some of which are obviously inaccurate, but some of his suggestions are worth thinking about, e.g. replace the 2N2222A with better performing RF-transistors. ArnoR may be very experienced in analog transistor circuit design. As far as i know, he himself did not yet provide measurement plots proving the achievements of his proposed design compared to the performance of the original LZ1AQ amplifier.
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For example claim 1:
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Output Transformer Issues
- Output transformer has too low an inductance (18?H, actually likely ~10.2?H).
- Results in too high a lower cutoff frequency (~500kHz or even 800kHz).
- Incorrect dimensioning limits low-frequency performance rather than the input resistance or loop inductance
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This assumption, IMHO, is ridiculous. The output transformer has not a "too low" inductivity of 10.2 ?H. I dont know where he takes this value from? The push-pull output transformer is wound on a high-permeability ferrite core. The open circuit incuctance of the transformer is likewise in the range of several hundreds of ?H. If he had measured this circuit on the lab bench, he would have known that the frequency range of an original LZ1AQ amplifier goes down much much lower than 800 kHz. In the files section there are many frequency plots which prove that.
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regards
Fred
