________________________________________ From: time-nuts-boun...@febo.com [time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths [bruce.griffi...@xtra.co.nz] Sent: Wednesday, September 16, 2009 21:06 To: ch...@chriscaudle.org; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Fundamental limits on performance
Chris Caudle wrote: > I found it interesting that one of the limits of stability seems to be the > ability to process the crystals at high temperatures to drive off > impurities. The JHU crystals are apparently in some type of glass > enclosure which can take the high temperatures, and the paper seemed to > indicate that the standard metal capped packages can't take the higher > temperatures. > > Bliley BFG61 package: http://www.bliley.com/index_088.htm > > Just seemed interesting, I would assume that the JHU guys know about those > types of advances in packaging, but the paper didn't mention it. I think it's safe to assume that the APL guys know a "lot" about this kind of packaging..<grin> > > Look at the JHU site there is a little on the oscillator. The BFG61 package uses an intermediate internal ceramic plate that more closely matches the thermal expansion of the quartz crystal. -- Similar to a fairly conventional "graded seal", I would imagine There is a huge amount of "art" in building this sort of package (actually, there's a lot of art in building high performance oscillators in general).. I would imagine that there are a very limited number of people who actually are skilled at making the package, sealing it, etc. It's not like it's a skill set or market that would justify training thousands of operators. Same kind of thing as any limited production item (like high performance electron gun cathodes, etc.) _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
