Hi The main question is - is there a PLL between the external ref and the OCXO? If so does it go through the DAC?
If there’s a PLL through the DAC, then bits do matter. If the DAC is simply a replacement for a trim pot, then it may not matter much at all. The OCXO will likely age more in a few days than the reported LSB resolution of the DAC. I’d bet DAC is not part of a PLL. Bob > On Nov 23, 2014, at 8:04 PM, Neil Schroeder <gign...@gmail.com> wrote: > > No but a little math based on your ocxo's range can help... but measuring > it in person does give you the best numbers. > > More precision and more bits WON'T hurt here and the application notes from > the leading crystal makers suggest a DAC front ended by a precision op amp > with and that the xo be followed by a buffer. So I took the nuclear option: > > http://www.analog.com/static/imported-files/circuit_notes/CN0257.pdf > > My Wenzels don't have a reference out and neither do any of my VCXOs, but > my $30 Vectron from Ebay does - so my circuit for it is modified to accept > its reference voltage (its also plugged into an ADF4001 now) > > NS > > > On Sun, Nov 23, 2014 at 4:56 PM, Bob Camp <kb...@n1k.org> wrote: > >> Hi >> >> About the only other question would be the proper resolution for the DAC. >> There’s not much of a way to to answer that one without playing with a >> woking original OCXO. >> >> Bob >> >>> On Nov 23, 2014, at 7:22 PM, Don Latham <d...@montana.com> wrote: >>> >>> No question about that. The morion does run a little warmer than the old >> unit >>> apparently did. Fan is temp-controlled, so I think OK. will monitor box >> temp >>> with a digital :-) thermometer, very poor resolution, but probably ok. >>> When I get the last obs done. will do a little blurb to the group. >>> Don >>> >>> Bob Camp >>>> Hi >>>> >>>> That sounds fine. Without knowing just what they did or didn’t do, it’s >> always >>>> worth being a bit careful. >>>> >>>> Bob >>>> >>>>> On Nov 23, 2014, at 6:40 PM, Don Latham <d...@montana.com> wrote: >>>>> >>>>> Running very nearly continuously for about 4 days now. The >> self-measured >>>>> jitter is mean 0 and sdev of 8 ps. I don't think there is a problem >> with the >>>>> Morion. I'm using my newly acquired cs source and a couple of z3801's >> for >>>>> checking. 1 bit on the SR's frequency calibration dac seems to be >> about 4-5 >>>>> parts in 10^-10 if I'm reading things right. Next test is a z3801 >> driving >>>>> the >>>>> external freq port on the sr to see if the frequency change direction >> of the >>>>> morion is OK. >>>>> The scope display output from the SR620 is great! >>>>> Lots to learn. Also have one of Said's units coming. Gone nuts for >> time, >>>>> won't >>>>> do anything much new, but it's new to me. All this to drive >> moonbounce... >>>>> Don >>>>> >>>>> >>>>> Bob Camp >>>>>> Hi >>>>>> >>>>>> If all the “good stuff” runs on the 90 MHz, the 5 MHz issue may not be >>>>>> important at all. It’s just something to watch for. If you start >> seeing >>>>>> data >>>>>> in two groups, each one 20 ps wide and separated by maybe 200 ps, you >> are >>>>>> seeing a problem from the 5 MHz. >>>>>> >>>>>> Running the box for a while before doing a full detailed cal is a >> very good >>>>>> idea. It’s a bit warm inside and some of the stuff is temperature >>>>>> sensitive. >>>>>> You want it to reach equilibrium. >>>>>> >>>>>> Bob >>>>>> >>>>>>> On Nov 23, 2014, at 1:06 AM, Don Latham <d...@montana.com> wrote: >>>>>>> >>>>>>> Ah. Got it finally! Doh. Just finished trying out the Morion this >>>>>>> afternoon. >>>>>>> Electrically works very well. Used a 7812 to drop the +15 volts from >> the >>>>>>> option 1 ocxo, there is enough power headroom to bring the Morion up >> from >>>>>>> cold >>>>>>> and run it comfortably. As you said, the control voltage for the >> original >>>>>>> is >>>>>>> indeed 5 v, and can be set by the internal d/a. The output of the >>>>>>> oscillator >>>>>>> passes through an emitter follower voltage adjuster and through a >> low-q >>>>>>> filter >>>>>>> to three stages of ECL buffer and then out to the 10 MHz system bus >> clock. >>>>>>> Another path proceeds to a relay-switched divide by 2 to the phase >>>>>>> detector >>>>>>> so >>>>>>> an external 5/10 MHz source can lock the internal oscillator. >>>>>>> The external 5/10 MHz source proceeds to the phase detector thru an >>>>>>> identical >>>>>>> buffer chain without the switched divider. The remainder of the >> clock >>>>>>> circuits is a multiplier to 90 MHz. >>>>>>> >>>>>>> I'll run the autocal tomorrow and then get some jitter stats if >> possible. >>>>>>> This >>>>>>> is an early specimen, s/n about 700 or so. I can imagine seldom >> used, and >>>>>>> sitting on standby for 20 years or so, pushing the ocxo out of >> tolerance. >>>>>>> >>>>>>> The saga continues; I may have to look for a 10 MHz replacement on >> epay, >>>>>>> there >>>>>>> isn't room to put in an Hp, unfortunately. >>>>>>> Don >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> Bob Camp >>>>>>>> Hi >>>>>>>> >>>>>>>> At least the Morion’s I have seen have 5 MHz crystals in them >> rather than >>>>>>>> 10 >>>>>>>> MHz. They have a 10 MHz output due to an internal doubler. Since the >>>>>>>> circuit >>>>>>>> is not perfect, there is cycle to cycle variation in the 10 MHz. >> It’s way >>>>>>>> more >>>>>>>> jitter (measured in picoseconds) than the oscillator has due to >> phase >>>>>>>> noise. >>>>>>>> My concern is that a counter might be bothered by this is some >> subtle >>>>>>>> way. >>>>>>>> >>>>>>>> Bob >>>>>>>> >>>>>>>>> On Nov 22, 2014, at 3:55 PM, Don Latham <d...@montana.com> wrote: >>>>>>>>> >>>>>>>>> Hi Bob: no. cobble, not double :-) A little research has me >> thinking I >>>>>>>>> can >>>>>>>>> easily adapt a morion. I can try it at least by starting with the >> morion >>>>>>>>> on >>>>>>>>> an >>>>>>>>> external power supply and patching the output and control voltages >> in to >>>>>>>>> the >>>>>>>>> sr. >>>>>>>>> >>>>>>>>> The sr620 has a control circuit which apparently accomplishes your >>>>>>>>> suggestions; they claim to use the internal oscillator for short >> term >>>>>>>>> and >>>>>>>>> "lock" it to a supplied external source for longer term. Probably >> has a >>>>>>>>> long >>>>>>>>> time constant on the built-in phase lock to do this. >>>>>>>>> >>>>>>>>> Anyhow, autocal calibrates everything except, guess what, the 10 >> mhz >>>>>>>>> source. >>>>>>>>> Thats done separately. >>>>>>>>> So a bootup self check shows OK even if the frequency standard is >> way >>>>>>>>> off. >>>>>>>>> >>>>>>>>> Onward and upward. >>>>>>>>> Don >>>>>>>>> >>>>>>>>> Bob Camp >>>>>>>>>> Hi >>>>>>>>>> >>>>>>>>>> I believe that the SR620 uses a “true” 10 MHz OCXO. I would be >> careful >>>>>>>>>> using a >>>>>>>>>> 5 MHz doubled to 10 OCXO. The counter may or may not be happy with >>>>>>>>>> sub-harmonic induced jitter. >>>>>>>>>> >>>>>>>>>> Best bet at the specs: >>>>>>>>>> >>>>>>>>>> +12V power >>>>>>>>>> 0-5V EFC >>>>>>>>>> Sine wave out +7dbm >>>>>>>>>> >>>>>>>>>> +/- 5x10^-9 0 to 70C >>>>>>>>>> >>>>>>>>>> Pinout - trace what you have. >>>>>>>>>> >>>>>>>>>> Bob >>>>>>>>>> >>>>>>>>>>> On Nov 21, 2014, at 6:59 PM, Don Latham <d...@montana.com> wrote: >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> So, I got a reasonable deal on a SR620 ho ho. Know your dealer. >> The >>>>>>>>>>> ocxo >>>>>>>>>>> is >>>>>>>>>>> out of tolerance. All self tests pass with flying colors, autocal >>>>>>>>>>> works >>>>>>>>>>> as >>>>>>>>>>> well. So the best parts are OK. >>>>>>>>>>> Does anyone: >>>>>>>>>>> 1) have a spare Isotemp OCXO36-53 10.000 MHz p/n 6-00051? >>>>>>>>>>> 2) know the specs, ie the input voltage/current and the control >>>>>>>>>>> voltage >>>>>>>>>>> span >>>>>>>>>>> and direction? pinout? >>>>>>>>>>> I have some Morion mv-89's and could easily cobble one in if it >> will >>>>>>>>>>> work. >>>>>>>>>>> Apparently a correct oscillator must be in place to use an >> external >>>>>>>>>>> source, >>>>>>>>>>> if >>>>>>>>>>> I read the manual right. >>>>>>>>>>> >>>>>>>>>>> 3) do we have a source for the schematics for the SR 620? >>>>>>>>>>> >>>>>>>>>>> The FTS 4060 is up, pumpin' and firmly locked. At least for now. >> That >>>>>>>>>>> dealer >>>>>>>>>>> was not lyin' >>>>>>>>>>> >>>>>>>>>>> Much thanks to all of you. >>>>>>>>>>> The adventure continues >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> -- >>>>>>>>>>> "The power of accurate observation is commonly called cynicism by >>>>>>>>>>> those >>>>>>>>>>> who >>>>>>>>>>> have not got it." >>>>>>>>>>> -George Bernard Shaw >>>>>>>>>>> >>>>>>>>>>> Dr. Don Latham AJ7LL >>>>>>>>>>> Six Mile Systems LLC >>>>>>>>>>> 17850 Six Mile Road >>>>>>>>>>> Huson, MT, 59846 >>>>>>>>>>> mail: POBox 404 >>>>>>>>>>> Frenchtown MT 59834-0404 >>>>>>>>>>> VOX 406-626-4304 >>>>>>>>>>> Skype: buffler2 >>>>>>>>>>> www.lightningforensics.com >>>>>>>>>>> www.sixmilesystems.com >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> _______________________________________________ >>>>>>>>>>> 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. >>>>>>>>>> >>>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> -- >>>>>>>>> "The power of accurate observation is commonly called cynicism by >> those >>>>>>>>> who >>>>>>>>> have not got it." >>>>>>>>> -George Bernard Shaw >>>>>>>>> >>>>>>>>> Dr. Don Latham AJ7LL >>>>>>>>> Six Mile Systems LLC >>>>>>>>> 17850 Six Mile Road >>>>>>>>> Huson, MT, 59846 >>>>>>>>> mail: POBox 404 >>>>>>>>> Frenchtown MT 59834-0404 >>>>>>>>> VOX 406-626-4304 >>>>>>>>> Skype: buffler2 >>>>>>>>> www.lightningforensics.com >>>>>>>>> www.sixmilesystems.com >>>>>>>>> >>>>>>>>> >>>>>>>>> _______________________________________________ >>>>>>>>> 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. >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> "The power of accurate observation is commonly called cynicism by >> those >>>>>>> who >>>>>>> have not got it." >>>>>>> -George Bernard Shaw >>>>>>> >>>>>>> Dr. Don Latham AJ7LL >>>>>>> Six Mile Systems LLC >>>>>>> 17850 Six Mile Road >>>>>>> Huson, MT, 59846 >>>>>>> mail: POBox 404 >>>>>>> Frenchtown MT 59834-0404 >>>>>>> VOX 406-626-4304 >>>>>>> Skype: buffler2 >>>>>>> www.lightningforensics.com >>>>>>> www.sixmilesystems.com >>>>>>> >>>>>>> >>>>>>> _______________________________________________ >>>>>>> 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. >>>>>> >>>>>> >>>>> >>>>> >>>>> -- >>>>> "The power of accurate observation is commonly called cynicism by >> those who >>>>> have not got it." >>>>> -George Bernard Shaw >>>>> >>>>> Dr. Don Latham AJ7LL >>>>> Six Mile Systems LLC >>>>> 17850 Six Mile Road >>>>> Huson, MT, 59846 >>>>> mail: POBox 404 >>>>> Frenchtown MT 59834-0404 >>>>> VOX 406-626-4304 >>>>> Skype: buffler2 >>>>> www.lightningforensics.com >>>>> www.sixmilesystems.com >>>>> >>>>> >>>>> _______________________________________________ >>>>> 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. >>>> >>>> >>> >>> >>> -- >>> "The power of accurate observation is commonly called cynicism by those >> who >>> have not got it." >>> -George Bernard Shaw >>> >>> Dr. Don Latham AJ7LL >>> Six Mile Systems LLC >>> 17850 Six Mile Road >>> Huson, MT, 59846 >>> mail: POBox 404 >>> Frenchtown MT 59834-0404 >>> VOX 406-626-4304 >>> Skype: buffler2 >>> www.lightningforensics.com >>> www.sixmilesystems.com >>> >>> >>> _______________________________________________ >>> 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.