Hi John,

I wonder if it might be better to put your considerable talent towards using some of the more recent high power devices? There are some nice 50V LDMOS devices available now, like the NXP BLF6G13L-250P and while the 10 Euro MRFE6S9160HS is unbeatable for price, the supply is going to dry up eventually. The NXP devices are not cheap at £120 but they out to be capable clean and reliable in a 250W 23cms PA. There are lower output devices, e.g. 35W and 60W but by the time all the other costs of making a useful amplifier are figured in its not that different.

Mike