Michael Bales wrote:
> My name is Mike - kb8dlm. I have spent a couple of months researching HF
> solid state PA designs, and simply would like to bounce a few ideas off of
> people who have a bit more experience than myself. I have been studying
> data sheets of a few HF power transistors, and
> just looking for some more consensus before I commit to a particular module.
> One option I've explored is based on the ST SD3932B LDMOSFET, rated at 400w,
> dissipating about 600w in the 2-30 MHz range. The idea here is to couple 2
> of these, each on their own board then use a combiner for apprx 1Kw out.
> The second option is based on the design in the 2010 ARRL handbook, but
> substituting the 151 MOSFETS with NXP BLF177's. I already have fairly
> beefy(and > new) 2500VA toroidal power transformer that is 100v ct.
> so that should give me more options too.
> Again, any input would be welcomed, either in the forum or email.
Most commercial designs use two FETs in push pull and then combine
the pairs, this has several advantages, the balanced collector/drain
current cancels preventing saturating the output ferrites and the second
harmonic is canceled out. It also allows class "B" operation.
--
Ron KA4INM - Next AReU meeting is on November 2, 2010 @ 7:30 pm
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