Toot

Written by Rasmus SA5RJS on 2025-01-19 at 21:21

4. First Test

I hooked up a current meter in series with the power supply and started to tweak the gate bias. The board draws 22 mA with the bias completely off. I turned the potentiometer until the current reached 42 mA, which should mean that each FET get about 10 mA of current.

I tested with the PA connected to the 13.2 V power supply and a few different power levels:

• 0.08 W in, 0.51 W out, (current not recorded)
• 0.16 W in, 4.07 W out, 2.3 A
• 0.26 W in, 11.0 W out, 3.6 A
• 0.51 W in, 28.8 W out, 5.8 A

The harmonic content was pretty terrible, as expected. I haven't added any low pass filter on the output yet. I've also heard that lower gate bias means more crossover distortion and non-linearity, so that makes sense.

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