As part of our "open source" project to create a reference design for a 1500
watt solid state amplifier ( http://www.k6if.com/ssamp/ ), we have designed a
printed circuit board to implement Helge Granberg's six band, five pole
Chebyshev low pass filters as shown in his QST article "MOSFET RF Power, An
Update." These filters are designed for use in a legal limit amplifier to
attenuate harmonics.
The PCB is roughly 6" x 13", double sided. We are going to have them made by
ExpressPCB, a quality commercial fab house. The design uses relays and
capacitors available from Digikey, and inductors that you need to wind yourself.
As you might expect, the cost of a PCB like this goes down when they are
ordered in quantity.
If you are thinking of building such an amplifier at some point, and would be
interested in a filter board, please let me know by email. The boards will
cost $50 each (unless we get a bunch of folks, in which case the price will go
down from there). Please note: these boards are a new design, they have not
been tested and are not guaranteed to work. Some rework may be necessary.
The ExpressPCB file for the board is on the web site - see the link on the
"Output Filters" page. If you find any bugs or have suggestions on how to
improve the board - I'd love to hear them too!
***dan, K6IF
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