sorry, Bob, I spaced this one. The dac is indeed a trimpot, and if the external source is enabled, the 1:1 pll controls the ocxo through, as you thought, a fast loop, about 2 sec t/c and the trimpot dac is not connected. The pll is an ecl phase detector and a pump, very simple. So the “zero point” of the oxco has no setting voltage? more thought needed!
Don > On Nov 23, 2014, at 7:34 PM, Bob Camp <kb...@n1k.org> wrote: > > 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. > _______________________________________________ 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.