Yes, it's because of the various types that you need to verify exactly what you have. A number of them are made to customer specifications with undocumented option numbers but if you have anything like an option 8 then you have the 1Hz to 20MHz version. Beware that to program the thing you need to provide +5V as well as the +15V to run it. Along with the output options, there are a slew of options on such things as ageing and temperature stability. If you have one from a telecom's cellular tower, it's likely to be of higher spec.
Steve On 26/07/2010, Bob Camp <li...@rtty.us> wrote: > Hi > > One issue with the FE's is they often show up as conversions. Various > sellers take the 1 pps version and hack in a 10 MHz output. There is a lot > of room for error in the conversion process. > > Bob > > > > On Jul 26, 2010, at 7:06 AM, Steve Rooke <sar10...@gmail.com> wrote: > >> Brice, >> >> On 26/07/2010, Heathkid <heath...@heathkid.com> wrote: >>> Last night, as suggested by several people on this list... I ordered a >>> Trimble Thunderbolt from Bob Mokia, fluke.l so I should be in pretty good >>> shape there to get started once it arrives. >> >> Sounds like your starting on the long path to time-nuttiness :) Bob >> has supplied a lot of stuff to people on this list and he will look >> after you if anything is amiss. >> >>> The counter I mentioned (it's a DFD4 - modified with the tcxo as the "a" >> ... >>> anyway). :) By the way, when I built it, I calibrated it by zero >>> beating >>> against WWV at 10 and 20 MHz. That was the best way I had at the time >>> and >>> if the DFD4 is now 7 Hz off after all these years... it's not doing so >>> bad >>> (based on it's limitations). >> >> Not bad considering it's a TCXO. >> >>> So... that's what that counter is for and not for what I'm doing now. >>> I'm >>> currently looking for a nice/used HP counter. Please don't think I'm >>> going >>> to use the DFD4 for measuring my Rb standards. It's a wonderful counter >>> for >>> what it was designed for and that's it. >> >> Dependant upon what your looking for in a counter, you could broaden >> your choices as there are other useful counters out there that may be >> more affordable but still as good. Try looking for a Racal-Dana 1992, >> preferably with the high stability option timebase (although these >> turn up seperately anyway and are a doddle to fit). It makes a nice >> footprint 1ns counter and can be referenced to your T'Bolt. >> >>> I'm not giving up on the FEI's anytime soon. I understand now that along >>> with the Trimble Thunderbolt (and a decent counter) I'll be on my way to >>> "getting started". >> >> You'll have to see if those FEI's are the programmable types which can >> be set to produce frequencies up to 20MHz. Do they have jut the D'Sub >> connector or have an RF connector as well. There are different >> variants of these produced by FEI under the same product code. >> >> 73 de Steve ZL3TUV & G8KVD >> >>> 73 Brice KA8MAV >>> >>> >>> ----- Original Message ----- >>> From: "Steve Rooke" <sar10...@gmail.com> >>> To: "Discussion of precise time and frequency measurement" >>> <time-nuts@febo.com> >>> Sent: Sunday, July 25, 2010 8:40 AM >>> Subject: Re: [time-nuts] Symmetricom X72 >>> >>> >>>> Excuse my replying to my own posting please. >>>> >>>> This post is really about the DFD1 frequency counter. >>>> >>>> Heathkid: You are comparing a Rb against a frequency counter with a >>>> TCXO that you tweaked yourself to calibrate it against no known >>>> frequency standard. Try running the three FEI-5660s for 24 hours and >>>> then measure the output of each with your frequency counter. Pick the >>>> mean of them and adjust your DFD1 to match that. At least you should >>>> be in a better position than you are now. >>>> >>>> As you built the DFD1 yourself, you should have the schematic and may >>>> be able to engineer in a connection for an external reference. There >>>> is plenty of people here who would be happy to advise you on a >>>> suitable interface if you can attach the part of the circuit where the >>>> TCXO is located. If you do get a T'Both, you would be able to use it >>>> as a reference or, perhaps, build in one of the FEI-5660s as an >>>> internal reference. The limiting factor though is how good is the >>>> circuit used in the DFD1 which will limit it's stability and accuracy. >>>> There are many factors, including input circuit, voltage regulation, >>>> counter stage design, level detection, etc. which have a major impact >>>> here. What I'm getting at is that to write-off a bunch of FEI-5660s >>>> after checking them with such a device as this, is a very poor >>>> decision. >>>> >>>> Maybe you could look at a better counter on fleeBay before you make >>>> further assumptions. >>>> >>>> 73, >>>> Steve >>>> >>>> On 26/07/2010, Steve Rooke <sar10...@gmail.com> wrote: >>>>> Sage advice Bill! >>>>> >>>>> Heathkid, you don't need another Rb unit when you have 3 perfectly >>>>> decent ones! You really need a standard to calibrate your Rb units to, >>>>> a Trimble Thunderbolt is likely to be the cheapest choice for you. Bob >>>>> Mokia, fluke.l, on fleeBay sells them separately or as a starter kit >>>>> with everything there to get you going. Once you have this up and >>>>> running for quite some time and see that things are looking stable in >>>>> the Lady Heather application, then you can start to think about >>>>> calibrating the FEI-5680's but only after you have run them in well. I >>>>> don't know your counter but does it have an input for an external >>>>> reference source? If so you will be able to use the T'Bolt as an >>>>> external reference for it, providing the required reference is 10MHz. >>>>> If it's not, you can divide down the T'Bolt's output to match. If your >>>>> frequency counter has no reference input (apart from throwing it in >>>>> the bin) you should be able to engineer it into the instrument, >>>>> depending on your skill set. >>>>> >>>>> So, first get yourself a frequency standard to work with, IE. a T'Bolt >>>>> or the like. >>>>> >>>>> My 2c worth, >>>>> Steve >>>>> >>>>> On 25/07/2010, WB6BNQ <wb6...@cox.net> wrote: >>>>>> To Bob and Stan (W1LE), >>>>>> [p.s. But not just to you two alone] >>>>>> >>>>>> >>>>>> Why complicate the answers to Heathkid (now Brice KA8MAV) with a bunch >>>>>> of >>>>>> different directions that should only be decided after one gains >>>>>> enough >>>>>> knowledge and understanding (they are not the same) to properly grasp >>>>>> the >>>>>> subject matter ? ? ? ? >>>>>> >>>>>> Clearly Heathkid needs some guidance. The form should be to start out >>>>>> with >>>>>> the very basics and get his feet on the ground. He already has three >>>>>> (3) >>>>>> Rb >>>>>> sources that should keep him busy for quite some time. However, his >>>>>> counter >>>>>> is really junk from a lab point of view. Nonetheless, even it can be >>>>>> useful >>>>>> if it is understood how to apply it after understanding its >>>>>> limitations. >>>>>> >>>>>> What Heathkid needs to understand is it is not about equipment. It is >>>>>> all >>>>>> about how to measure and account for errors and unknowns. Actually, >>>>>> quite >>>>>> a >>>>>> daunting task depending upon the level of achievement. >>>>>> >>>>>> I agree he needs some kind of external reference and I agree the >>>>>> Trimble >>>>>> Thunderbolt (Tbolt) would be the right item for his true reference. >>>>>> Even >>>>>> the Tbolt has its issues that need to be understood. >>>>>> >>>>>> He will also need a method of comparison. The oscilloscope is a good >>>>>> start >>>>>> but very tedious. Here Burt's project would help him a lot when Burt >>>>>> gets >>>>>> it done. I guess he is close. I guess, also, the PICTIC II would fit >>>>>> the >>>>>> bill after he understands what it is. >>>>>> >>>>>> Still he needs to understand how to apply and use this stuff. >>>>>> Confusing >>>>>> him >>>>>> with suggesting all of the different Rb sources available is only >>>>>> making >>>>>> him >>>>>> think a better one { relative statement } would be the answer which is >>>>>> not >>>>>> true. His FEI-5680's are so much better for his particular level, it >>>>>> is >>>>>> not >>>>>> even funny. >>>>>> >>>>>> What has not been asked of him is what are his goals and intentions. >>>>>> If >>>>>> it >>>>>> is to just say you have an atomic frequency reference, then sit the >>>>>> FEI-5680 >>>>>> on the coffee table; job done. One cannot be properly guided if the >>>>>> goals >>>>>> are unknown. >>>>>> >>>>>> Bill....WB6BNQ >>>>>> >>>>>> >>>>>> Bob Camp wrote: >>>>>> >>>>>>> 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" <li...@rtty.us> >>>>>>>> To: "Discussion of precise time and frequency measurement" >>>>>>>> <time-nuts@febo.com> >>>>>>>> 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 -- time-nuts@febo.com >>>>>>>>>> To unsubscribe, go to >>>>>>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>>>>>>> and follow the instructions there. >>>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> _______________________________________________ >>>>>>>>> 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. >>>>>>>> >>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> 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. >>>>>>>> >>>>>>> >>>>>>> _______________________________________________ >>>>>>> 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. >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> 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. >>>>>> >>>>> >>>>> >>>>> -- >>>>> Steve Rooke - ZL3TUV & G8KVD >>>>> The only reason for time is so that everything doesn't happen at once. >>>>> - Einstein >>>>> >>>> >>>> >>>> -- >>>> Steve Rooke - ZL3TUV & G8KVD >>>> The only reason for time is so that everything doesn't happen at once. >>>> - Einstein >>>> >>>> _______________________________________________ >>>> 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. >>> >>> >>> _______________________________________________ >>> 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. >>> >> >> >> -- >> Steve Rooke - ZL3TUV & G8KVD >> The only reason for time is so that everything doesn't happen at once. >> - Einstein >> >> _______________________________________________ >> 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. >> > > _______________________________________________ > 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. > -- Steve Rooke - ZL3TUV & G8KVD The only reason for time is so that everything doesn't happen at once. - Einstein _______________________________________________ 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.