12-06-2013, 07:25 PM
Ok Al,
I attach the waveforms for gate, drain and output.
I tried a new the 18 Turn coil and there was a reduction in the heat of the coil, now about 60C. I also wound an oval coil, this with a few changes into a semi bone shape
works quite well but the standing current (No Load) is very high around 2A.
I tried different combinations of C etc with frequencies up to 500KHz but the output is very low and the Fets get hot.
The heat is the killer here with all these options, I can't sit the radio over something putting out 20W of heat.
At the end of the day I reckon I will have to be content to charge the batteries at 50- 100mA and not run the Radio from the "Adapter"
I have no experience of Fets and their biasing etc, the waveforms are gate 10V pp (limited by the 10V Zener) and Drain 60V pp. Note the ringing on both waveforms.
Any enlightenment re using FETs would be most welcome.
Mike
I attach the waveforms for gate, drain and output.
I tried a new the 18 Turn coil and there was a reduction in the heat of the coil, now about 60C. I also wound an oval coil, this with a few changes into a semi bone shape
works quite well but the standing current (No Load) is very high around 2A.
I tried different combinations of C etc with frequencies up to 500KHz but the output is very low and the Fets get hot.
The heat is the killer here with all these options, I can't sit the radio over something putting out 20W of heat.
At the end of the day I reckon I will have to be content to charge the batteries at 50- 100mA and not run the Radio from the "Adapter"
I have no experience of Fets and their biasing etc, the waveforms are gate 10V pp (limited by the 10V Zener) and Drain 60V pp. Note the ringing on both waveforms.
Any enlightenment re using FETs would be most welcome.
Mike
