Dan Levin wrote:
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
Was the CWAZ (QST Feb. '99) considered? Only a few extra
components but significantly superior specs.
Are you saying that the design has never been breadboarded
and tested or is "have not been tested and are not guaranteed
to work" a legal disclaimer?
However, to avoid messy point-to-point wiring, etc. I'd be
interested at $50. or less (already have most of the components).
Add me to the list, please!
Just looked at the design site (nicely done) and it sure looks
like a ton of work when used solid state amps are readily
available that run Eight 2SC2879's and may easily be converted
for Ham use (swap out the transformers and splitter/combiners).
A pair of them (rather than four) run off commonly available
12vdc deep-cycle batteries (OK, a bank of 100Ah batteries),
recharged from AC or solar.
Need to add a splitter in front, a combiner at the outputs,
a filter similar to what you propose, and a swr etc. circuit
as you have proposed, and it is done.
(You also will yank some more amps out of the illegal operator
world of CBers and Freebanders!)
73, doc kd4e
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