[Amps] High voltage MOSFETs

[Steve Thompson]

I think most of these are products inherited when they took over 
APT. There's a number of app notes to go with them - they were 
originally designed for narrow band saturated cw use and one 
common theme is the problems of trying to use them as linear amps. 
Bias control is a problem and reduced supply voltage is 
recommended, even then linearity is poor. One 'linear' design 
quotes IMD as -25dB ref pep or -19dBc!

I dare say they are capable of better than that, but it won't be 
simple and straightforward.

Steve

> For those interested, MIcrosemi has a line of relatively high voltage
> RF MOSFETs:
>
> https://www.microsemi.com/existing-parts/parts/81771
>
> One intriguing possibility with these is direct coupling (through an
> LP filter and DC isolation of course) to 50 ohm coax. No transformer
> needed.
>
> Something to think about.
>
> 73, Bill W6WRT