I have written up my experience building this Class-E PA for LF here:

http://people.physics.anu.edu.au/~dxt103/class-e/

Maybe other beginner LF operators will find this useful.

73, Dimtris VK1SV

2012/8/9 Dimitrios Tsifakis <[email protected]>:
> Hello LF group,
>
> I am building a 200 W Class-E transmitter for LF but keep killing the
> capacitors in the output circuit (both C1 and C2 according to the
> schematic in  Sokal's QST article). I have used a mixture WIMA
> polypropylene MKP10, MKP4 and  FKP1 caps and I haven't damaged any FKP
> ones so far. Should I not bother with MKP and use only FKP caps or is
> there any other type of capacitor what will do the job? I need a
> couple of hundred of nanofarads. The voltage rating of the caps I
> destroyed was 400 VDC or 250 VAC. I can see that these caps have a
> decreasing AC rating as the frequency goes up, but that's what I had
> in the junk box at the time...
>
> The mode of failure of these MKP10 0.1 400 VDC caps is interesting
> too, they seem to go down in capacitance as the damage progresses.
>
> Any advice is appreciated.
>
> 73, Dimitris VK1SV/SV1DET
>