I am trying to build a set of lp filters for the ham bands for use with
the 600w motorola designed fet amplifier described in last months qsl
..I have successfully modelled suitable filters using pspice using 3
series inductors with 2 parallel caps for each band but I notice the
current in the caps can be several amps peak. values range from 150 to
3000pf. Can ceramics be used? Or do I need several parallel silver mica
caps? How much power can one dissipate in these caps? Near the corner
frequency there is as much as 6db gain under low load conditions and
this exacerbates the problem. I could move the corner further up so
that the filter is not excited at the peak current, but then I will
probably have to increase the number of poles to 7 from 5 to get enough
attenuation at the third harmonic. Is there a better filter
architecture that minimizes cap current?