I had a bad experience with chinese sellers: I got a Z3815A with the Furuno GPS enclosure completely rusted and a LPFRS that I suspect was submerged in water: rusted and corroded internally tough still working... the seller has agreed to send another one.
On Thu, Dec 1, 2011 at 11:18 AM, Attila Kinali <[email protected]> wrote: > On Thu, 1 Dec 2011 01:00:44 -0500 > "Steve ." <[email protected]> wrote: > > > Note the corrosion around the cheaper metal parts (screws, spacers, > shell). > > I can't speak for the FE-5680A, but when i see something like this in the > > instruments i maintain it's a tale-tale sign gas mitigation. > > I have to agree with Bill that there is no corrosion. At least i dont > see any, but on the head of the Rb cell. > > From the chemistry point, Rb or the noble gas buffer in the cell will > not corrode any metals if they would leak. Because noble gas are noble > and nearly completely inert (at least at the temperatures we are talking > about) and Rb is less noble than anything else you will find in there, > hence will oxidize first. > > There is a very slimm chance that Rb salts (after Rb has been oxidized) > could lead to an acidic reaction. But i can neither prove or disprove > that with my limited chemistry knowledge. > > But in this case, it's not Rb or any of its salt that's the culprit. > If you have a look at http://n1.taur.dk/fe5680a-2/IMG_1393.JPG > you see that the corrosion around the Rb tube is at the spot where > two transistors are soldered to the tube. The metal of the transistors > is copper plated with tin and soldered with a tin based solder. > What you'll get here is an sacrifacial anode effect, ie the copper > does oxidize the less noble iron/steal. > > > Other than that one spot, i have to say that the whole device looks > like new. No dirt, no corrosion where you'd expect it. Even the solder > joints look like new. > > Oh yes, if you mean http://n1.taur.dk/fe5680a-2/IMG_1398.JPG looks like > a corroded crystal contact, i have to disapoint you. All you see there > a not so ideal solder joint. Ie the solder wasnt heated well or did take > too long to cool down, which lead to a partial crystalization of the > surface. This then looks a little bit rough and can give the impression > of corrosion if one expects a completely flat and shiny surface. > > > Attila Kinali > -- > Why does it take years to find the answers to > the questions one should have asked long ago? > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
