Rob, the surplus place I bought it from is Apex Electronics; they're a bit north of Los Angeles, CA, and for all practical purposes in the desert. They have a fairly large building (that's pretty much filled to the gills), and an open yard that's about 3x the size of the building with all manner of stuff scattered about in it - scrap metal, parts, instrumentation, demilled 2" rocket launcher pods, a few partial light plane fuselages, lord only knows what else... As someone who lives in the northeast in the US, where we get four seasons and have frequent precipitation, it's a bit surreal for me to go somewhere where things like this are outside in the weather, but they very rarely get rain where they are, and never see snow or sleet. Often the gear is at least somewhat protected from rain by being under some sort of cover, but I believe that the precip is so infrequent and so light when it does come that it causes little harm. In this case, the 203A had been more or less in the open, in a steadily dwindling pile of stuff that I'd looked at over several visits. The day I finally bought it, I found it sitting on a table in the open and standing on its back, face up IIRC. It had rained the night before, as there were some puddles on the ground. My guess is that it had recently been upended and the rain came at such an angle that it rinsed the bottom cover off but not the top. The front panel was pretty clean.
Now the DUST, on the other hand... I don't recall that I've posted
this pic before, but I got the 5232A on the same trip as the 203A. It was on an outdoor shelf, up on top and just beneath a makeshift roof made of corrugated metal. I've no idea how long it had been out there, but couldn't tell for certain that it was grey till I cleaned it off!
From a Bing maps aerial view (though the stuff in the yard looks like great piles of trash, there are actually some cool things to be found if you dig and poke):
-Pat