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Grounded gate? Not too likely with the IRF 510. You will need 5V
drive at least, at all full current! Since a grounded gate(base, grid) amp has only voltage gain, you would have a theoretical gain of maybe 3db at 12V, 6db@24V, and so on,but given unity gain from the IRF 510 at 12V grounded source at VHF, maybe unity or worse real world at VHF regardless of supply voltage. The IRF 510 has a maximum peak voltage of 100, thus a maximum safe supply of around 34. Of course, a tube with several hundred volts supply(or several KV for a big one) is quite another matter, as are those 1KV peak MOSFETS as seen in some Class E 160M/80M rigs. No idea what input C is in the latter, though. Lastly, at grounded gate you still get the same voltage-variable 135pf gate-source C as your input C, you just get out of the Miller C, which is an estimated 22pf times 2 for an MF/HF rig with 12V supply and 12V drive, or times 3.5 for a 30V supply. Input loss gets damned high in this capacitance, and this is why a device that(grounded-source) at MF has 30dB gain has 10dB gain at VHF. |
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