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RAD-Hardening Spacecraft



Our NATSweb satellite we are trying to build in one month will pass
through the Van Allen belts 4 times a day.  I need help in 2 areas:

1)  The Final RF Power Amps will be directly connected to the power
bus.  Can a high energey particle cause conduction of the final PA
junctions, thus shorting the power bus, causing a current peak,
avalanche breakdown and thus total failure of the system?  If such a
scenario is possible, then resettable circuit breakers of some sort
will be required and I dont have any simple ideas...  Help?

2)  We need RAD-HARDENED chips for our two KPC-3+ TNC's.  Can anyone
help locate a source?  Here are the chips needed:

   CPU    MC68HC11F1
   ROM    ROM 32 ?
   RAM    RAM 32 ?
   RS232  14C88
   OPamps LMC6034IN
   MODEM  73M223
          AD8402  (controlable pots?)
   5v Reg MIC2951
   OPamps LMC6032IN
   Logic  74HC00
          74HC14
          74HC374
         
My local guru says that even normal parts from different manufactures vary
by as much as 1000:1 in radiation sensitivity depending on manufacturing
tolerences.  Who makes the best parts?

3) Looks like we can do without the 14C88 if we dont use the serial port
on Orbit.  Does anyone see any other power savers?  We could replace the
voltage vairable pots in the AD8402 with fixed voltage dividers.  How much
power will we save?

Thaanks for your help!

de WB4APR, Bob


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