On Mon, Feb 10, 2025 at 12:41 PM, Nils wrote:
The transformer there ist trifilar with 18uH each (5 trifilar turns on a toroidal core, u=1000, 10x6x4 mm). He probably recalculated the inductance.
In the older original LZ1AQ AAA-1B that i own, the transformer is on a 10 mm diameter blue coated Siemens/TDK Sifferit N30 toroid core, ?i = 4300.
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5 turns wound on this core would give an inductivitiy of approx. 45 ?H. The lower -3 dB cutoff frequency of a transformer is determined by the point where the transformer's primary inductance has the same impedance as the impedance driving it. Let's assume 50 Ohms. That results in a lower cutoff frequency of roughly 170 kHz. Below the cutoff frequency the transformer behaves like a low pass filter with a slope dropping with approx. 6 dB / octave. I dont know, wether the newer versions now have a different output push-pull transformer.
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If i did a mistake in my calculation please correct me.
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regards
Fred
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