Hi No, the LPRO is not obviously better than the FE's, depending on which version of the 5680 you have. The 5680 comes in two common varieties, one only has a 1 PPS output, the other will put out 10 MHz as well. Both can be digitally tuned to come up with oddball frequencies in the vicinity of their intended output.
Bob On Jul 24, 2010, at 5:46 PM, Heathkid wrote: > Bob, so you're saying the Efratom LPRO is better than the three FE-5680A's I > already have? Sounds like I do need a TBolt anyway. > > ----- Original Message ----- From: "Bob Camp" <[email protected]> > To: "Discussion of precise time and frequency measurement" > <[email protected]> > Sent: Saturday, July 24, 2010 5:20 PM > Subject: Re: [time-nuts] Symmetricom X72 > > >> Hi >> >> The only way to be sure of what's going on is to have several (hopefully) >> accurate references. With at least three you can begin to guess how good >> they are. >> >> The TBolt is different from the Rb in a couple of regards: >> >> 1) It's short term stability isn't as good when locked tightly to the GPS. >> 2) It's long term stability is much better than the Rb when it's locked. >> 3) It's easier to tell what's happening with it if you hook up a PC and the >> Lady Heather (free) program. >> >> The Rb will need a couple of things to make it play right: >> >> 1) It's got to have a pretty good heat sink on it. An 8 x 10" piece of 1/4" >> aluminum is a reasonable start >> 2) It's got to be run for a while (possibly 24 hours) before it will be >> stable >> 3) You need to watch the lock, and lamp voltages to be sure it's not doing >> something crazy. >> >> My recommendation based on cost is the Efratom LPRO for a cheap Rb. They are >> in the ~$60 range and seem to work pretty well. >> >> Setup wise, I would get a TBolt in addition to the Rb. You need something to >> calibrate the Rb (and your counter TCXO) against. Both are "secondary" >> standards. They (unlike a Cesium) are adjusted to match a known good >> reference. >> >> Once you have the Rb and the TBolt, next step is up to you. Cesium is always >> an alternative, so's a Hydrogen Maser .... >> >> Bob >> >> >> On Jul 24, 2010, at 3:32 PM, Heathkid wrote: >> >>> Hello Bob, >>> >>> What would you recommend? I already have three FE-5680A Rb standards >>> (which I'm quickly learning likely aren't worth the powder to blow them to >>> (*insert your own word here*). Okay, that was probably my first mistake >>> (thoughts?). >>> >>> My frequency counter is one I built from a kit from aade.com that has the >>> TCXO option (although I had to tweak it myself so I have NO idea how close >>> it is to any accuracy or precision). I have access to some really nice HP >>> counters at work so that's my next step is to try one of those. My DFD4 >>> measured the output of one of my 5680A's to 10.000.007 MHz after about a 10 >>> minute warm-up. I don't know which one is off. Reading the specs on the >>> 5680A's before I bought them looked like they were pretty decent. I'm >>> learning... >>> >>> So, what "reasonably priced" Rb standard would you recommend? >>> >>> Should my next step in this process be a Trimble Thunderbolt? Am I >>> starting over? >>> >>> Thanks... >>> >>> ----- Original Message ----- From: "Bob Camp" <[email protected]> >>> To: "Discussion of precise time and frequency measurement" >>> <[email protected]> >>> Sent: Saturday, July 24, 2010 9:31 AM >>> Subject: Re: [time-nuts] Symmetricom X72 >>> >>> >>>> Hi >>>> >>>> At least looking at the spec sheet it's not really very impressive. >>>> >>>> Bob >>>> >>>> >>>> On Jul 23, 2010, at 11:06 PM, Heathkid wrote: >>>> >>>>> Hello. Does anyone have any experience with the Symmetricom X72? >>>>> >>>>> Thanks... >>>>> >>>>> _______________________________________________ >>>>> 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. >>> >>> >>> _______________________________________________ >>> 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. > > > _______________________________________________ > 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.
