lowpass 150MHz, 150 Watts

[Krobelus]

Hi,

i must design a lowpass filter with cutoff at 150MHz. As far as i understand, a chebyshev pi LC needs a inductance of far below 1uH. In this region i can only find SMD type inductances that can not endure such high powers.

Where can i get such a low inductance? Do you have any other good design ideas for a low pass filter? Maybe some stripline architecture?

Cheers,

Sebastian

 

[BigBoss]

You can not realize this high power filter with standard SMD components.In fact, you don't need SMD components at that frequency.
Air wounded (or ferrite cored to increase the inductance value) coils with high current carrying wires should be used.To decrease the losses, silver plated copper tubes are best components.
Thin silver plated high current carrying strips may also be used.Radio Amateurs have so much experiences, ask them.
Be careful also Capacitors !!! Capacitors will be under very high RF voltages.. Don't forget otherwise your capacitors will powww....( Peak capacitor voltage can be as much as 85V+)

 

[biff44]

yes, u will need to wind your own coils, copper or silver wire with air core is probably the best choice. capacitors to ground should be very high voltage breakdown...probably porcelain type. the coils will get hot, so getting the heat out may be a problem. Arcing may be an issue too, especially if u are not operating at sea level. I would do it all on a thick FR4 board with very little metal at the top to minimize arcing.