Just trying to make the donut on another HF oscillator circuit of mine since I didn't have any more knob capacitors like I thought. It had a much smaller diameter primary and was still even able to make the donut, but it was only a small one that hugged the windings. The fields were too small and concentrated. After making the coil wider it still made the donut but it was also a little too hot to run for long periods since I don't want to damage the glass. I can probably just try to tune the thing to run at less current but before that I might as well also play around with modulating it also.
While I don't want to make it seem easier than it actually is, I will say that I was able to get this one going without a lot of effort just like the first one.. but it did take a little more tweaking. It was difficult to maintain a donut on this one when increasing the primary inductance too much and leaving all other values the same. It likes about ~18mhz with a 100pf tank cap.
I've also got this copper strip on the gate running over with a 90 in it to the cap that also could be making a difference. I think at the time I first made it I was playing around with trying to shift the phase relation of the gate and drain voltages. I'm also using 1/8" copper tube for the other circuit and just solid 12awg on this one.
26 июн 2024
