In article ,
says...
Dear all
I have seen posts in the past about this issue
My friend has acquired a unit with the output stage defunct.
Any ideas about what the problem is likely to be and the solution?

Thanks
Richard

They tend to get fried by reverse power application. Best solution
would be to replace it with a part from a donor unit. Next bet thing
would probably be a 50-ohm MMIC like a GALI-5 that's capable of similar
gain and output power. I don't remember if the 8640B's output-power
sampler is built into its output stage, though; if it is, then some
careful hacking might be necessary.

-- jm

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