>Dave D'Epagnier wrote:
>
>> I'm intrigued by the prospect of not having to fuss with tuning every
>> time I change frequencies and especially not having to obnoxiously
>> tune up on the air.
>> So, I'm looking into designing and building a 1-1.5kw broadband solid
>> state amplifier that needs no tuning, and considering using Motorola
>
>You probably know this, but Motorola have produced lots of application
>notes on using their devices for this sort of application. Eg AN758, 'A
>Two Stage 1kW Solid-State Linear Amplifier'. This uses 8xMRF428 + 2 x
>MRF427A's.
>
>Most, if not all the earlier application notes (including AN768) can be
>found in 'RF Application Reports', HB215/D, which is a soft-backed book
>over 500 pages long. You can (or at least could) get this free by
>ordering from Motorola's web site. A gold-mine of information. Some of
>the earlier editions of this book are even better than the late ones -
>hence I hang on to my old editions.
>
>See http://www.maneapc.demon.co.uk/motorola/ for UK hams. I think
>www.motorola.com is better for the US.
>
>To me, the effort of building a tube amp, and tuning it, seems almost
>trivial in comparison to building these solid state ones. I also expect
>the solid state amp will cost a lot more than a tube amp built from
>surplus tubes
Indeed, David. To produce 1500 watts out with solid-state devices at
28MHz, one needs a 3000 or more watts DC supply. Pulling this off at
under 50vdc, is hardly a piece of cake.
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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