I don't know what designs you are familiar with, but combiner losses don't
usually impact significantly on efficiency. That's why they are used in
high-efficiency AM BC transmitters...
The use of modules of a few hundred watts rating combined together actually
increases the attractiveness of big SSPAs. You can start by building, say, a
500W amp. Then when the fancy takes you it's no big deal to build a second
500Wamp., (which doesn't HAVE to be identical to the first...) combine the
two and end-up with a kW PA. A bit more work, and you can go up to perhaps
1500W, or 2kW. That's surely an ideal ugrade route for hams. It is for this
one, who is putting together a new station after a long period QRT.
I've no wish to get into a silly argument regarding solid state versus
thermionics. I'm of an age where I'm familiar with both technologies and my
professional CV/resume continues to include the ability to design tube
circuitry. My original post really wanted to say that the amateur approach
of continuing to look at transmitters/PAs in the open-loop way in which they
were in the 1940s/50's isn't entirely appropriate with modern devices, and
to suggest that we could do better.
73
Chris
GW4DGU
EME without a tube in the station!
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