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 <[email protected]> wrote: > Brice, > > On 26/07/2010, Heathkid <[email protected]> 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" <[email protected]> >> To: "Discussion of precise time and frequency measurement" >> <[email protected]> >> 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 <[email protected]> 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 <[email protected]> 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" <[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. >>>>> >>>> >>>> >>>> -- >>>> 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 -- [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. >> > > > -- > Steve Rooke - ZL3TUV & G8KVD > The only reason for time is so that everything doesn't happen at once. > - Einstein > > _______________________________________________ > 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.
