I bought two HP 5345A's for short money on e-Pay. The second one is the organ donor !! I bought these primarily because it has a 1,000 second gate time. When using a GPSDO as the reference, I can resolve down to mHz (If I believe that !!). But, the resolution is a lot better than the HP's that have a 10 second Gate Time.
73, Dick, W1KSZ -----Original Message----- >From: Heathkid <[email protected]> >Sent: Jul 25, 2010 12:55 PM >To: Discussion of precise time and frequency measurement <[email protected]> >Subject: Re: [time-nuts] Symmetricom X72 > >Thanks Bob. I'm understanding a lot more now. The FE-5680A's that I have >output both the 1pps as well as 10 MHz (and programmable to other >frequencies). Yes, I also understand now how the Rb physics package and the >DDS work together to come up with the output frequency. > >With the TBolt on the way now... and in the process of looking for a >good/used "real" counter... I'll get there. :) > >Best regards, >Brice > >----- Original Message ----- >From: "Bob Camp" <[email protected]> >To: "Discussion of precise time and frequency measurement" ><[email protected]> >Sent: Sunday, July 25, 2010 11:01 AM >Subject: Re: [time-nuts] Symmetricom X72 > > >> 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. > > >_______________________________________________ >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.
