[Amps] MOSFET amp for 80 m

[Angel Vilaseca]

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