[time-nuts] ocxo

Bob Camp kb8tq at n1k.org
Sun Nov 23 19:56:06 EST 2014


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 <djl at 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 <djl at 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 <djl at 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 <djl at 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 <djl at 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 at febo.com
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>>>>>>>>> and follow the instructions there.
>>>>>>>> 
>>>>>>>> _______________________________________________
>>>>>>>> time-nuts mailing list -- time-nuts at febo.com
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>>>>>>>> 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 at 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 at febo.com
>>>>>> To unsubscribe, go to
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>>>>>> 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 at febo.com
>>>>> To unsubscribe, go to
>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>> and follow the instructions there.
>>>> 
>>>> _______________________________________________
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>>>> 
>>> 
>>> 
>>> --
>>> "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 at febo.com
>>> To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
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>> 
>> 
> 
> 
> -- 
> "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 at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



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