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1 kilowatt Power Amplifier at 430 MHz

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Shoma Chandorkar

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I wand to design 1kilowatt of SSPA using phillips- BLF578 in class AB operation. which type of impedance matching is required . can anybody help me to design I/P and O/ P matching circuitary? What are all the steps to design PA?
 
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alperuslu

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With making Loadpull or source pull analysis you can determine which output/input impedance gives the appropriate power at the output of the PA. You can even simulate it with very accurately using most popular EDA softwares like agilent ads. I prefer to read Gonzales' Amplifiers book.

Kind Regards,
ALP
 

flatulent

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For these higher power levels, using several lower power amplifiers which are combined is cheaper, and much more reliable. The most optimum way is push-pull initial stages which are combined with quarature hybrids. Possiby in a "tree" of several stages.
 

vfone

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The price of BLF578 is about $350. To burn it (due to incorrect design) needs just couple of seconds.
As was mentioned, I would go for combined amplifiers, or use a metalo-ceramic tube.
 

G0HZU

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A 1kW PA at 430MHz is quite a beast. With class AB bias you will need to think carefully about thermal management issues. This unit will get hot due to the efficiency of class AB.

Also you will need a very big power supply to test it. Also you have health and safety issues during development.

Have you addressed all the above already?

I'm still uncertain why there is a need for a class AB amplifier at this power level at 430MHz. Are you designing it for amateur radio use?
 

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