[Amps] MOSFET amp for 80 m

[Roger Graves]

Angel, Manfred may reply for himself, but from one of his webpages https://ludens.cl/Electron/mosfetamps/amps.html <https://ludens.cl/Electron/mosfetamps/amps.html> his analysis of the circuit shows that the peak voltage on the primary is 25V, which gives 6.3W on 48 Ohms. This is because when one mosfet goes to saturation, the voltage on the non-conducting mosfet goes to almost twice the supply voltage, Vcc + (Vcc-Vsat), so the total peak primary voltage is 2 X (Vcc-Vsat). Someone will surely correct me if I got this wrong.

73, Roger

> On Jul 17, 2018, at 7:29 AM, Angel Vilaseca <avilaseca at bluewin.ch> wrote:
> 
> Hello everyone,
> 
> On this page,
> 
> http://lpistor.chez-alice.fr/pairf510.htm
> 
> I found a MOSFET amp description that does not need an output transformer. The author says that the output impedance of the transistors is 48 Ohms and that a balun is enough.
> How can this amplifier have such a high output impedance?
> 
> And most importantly, if the output impedance is 48 Ohms and the supply voltage is 13.8V, then how can the output power be 5-6 W?
> If the formula V ** 2 / R is used, that is 13.8 * 13.8 / 48, the output power should be less than 4 W.
> 
> Best regards
> 
> Angel Vilaseca HB9SLV
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