[time-nuts] ocxo

Sun Nov 23 18:40:08 EST 2014

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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>>>>>
>>>>> _______________________________________________
>>>>> 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
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>>>
>>> _______________________________________________
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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
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>> 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