Oscilloquartz 8663-XS stability problem
I recently constructed a homebrew 10MHz distribution amp.
It has provision for both an external 10MHz source such as a GPSDO or an internal OCXO.
For the internal OCXO I chose a used Oscilloquartz 8663-XS from China.
When I began testing the unit I discovered an issue with frequency / temperature stability.
I plotted a graph that shows the external temperature of the OCXO can as the device warms up.
It stabilises at 60degC after around 45 minutes.
I also plotted the frequency error measured using a Racal 1998 with an external 10MHz clock from a GPSDO.
The frequency also appears to stabilise after around 45 minutes.
[cid:0acb1b9d-a986-47a3-85de-53b95bb8479e]
So far so good.
However I find that if I leave the unit running for a few hours, the frequency gradually drifts upwards by up to 0.5Hz.
That is well outside the 8663-XS specification. It is supposed to remain within 4x10^-9 from -20 to +70degC (I assume that is external ambient temp).
The OCXO temperature (as measured on the outer can) remains constant at 60 degC.
The tuning voltage and the supply voltage (12V) also remain constant.
The tuning voltage comes from a LH0070 10V precision reference and a 10 turn 10K trimmer.
I expected the tuning voltage required for 10MHz to be around 5V. The spec indicates a range of 0->10V.
I found that the tuning voltage needed to be set to just below 10V to get 10MHz.
Initially I thought that perhaps that's because it's an old used device.
Subsequent tests however make me think it's related to temperature.
I find that if I remove the equipment case lid, the frequency drifts slowly downwards.
When I replace the lid, the frequency error slowly recovers.
I assume the OCXO temperature drops slightly when the lid is removed despite it having ventilation slots directly above the OCXO.
I expected the OCXO internal temperature to be maintained to within around +/- 1degC by the heater control circuit such that it would compensate for small external temperature variations.
I am at a loss to explain what is going on and am running out of ideas.
It appears that the OCXO internal temperature regulation is not working as well as it should.
Is it just my particular device that behaves in this way or is it a common issue with this OCXO?
I don't want to buy another used device from China (around 40 GBP) only to find the same problem.
I would welcome any thoughts/suggestions from the experts here at time-nuts.
For the full story, please refer to my recent thread in the eevblog forum:-
https://www.eevblog.com/forum/projects/oscilloquartz-8663-xs-ocxo/
[cid:18711b70-068e-474b-8ab5-74e886152aa1]
Regards,
Brian.
Hi
The plot links don’t work so this is pretty generic:
Any OCXO that has been off for a while will take a while to stabilize. The drift as is does so is in the “who knows how much” range.
Temperature is typically specified as “ambient”. Effectively, that means air temperature. If the air is not moving, that can be pretty tough to work out.
What can be worked out is that air inside a sealed enclosure is going to be “pretty warm” with an OCXO pumping energy into it. Pop off the lid and it will change.
All that said, you only can really know if it meets temperature spec with a proper temperature run. Trying to work things out without proper testing is near impossible.
Best guess on any eBay surplus item: It’s been treated very poorly, it may well have issues.
Bob
On Oct 27, 2023, at 10:15 AM, Brian K via time-nuts time-nuts@lists.febo.com wrote:
I recently constructed a homebrew 10MHz distribution amp.
It has provision for both an external 10MHz source such as a GPSDO or an internal OCXO.
For the internal OCXO I chose a used Oscilloquartz 8663-XS from China.
When I began testing the unit I discovered an issue with frequency / temperature stability.
I plotted a graph that shows the external temperature of the OCXO can as the device warms up.
It stabilises at 60degC after around 45 minutes.
I also plotted the frequency error measured using a Racal 1998 with an external 10MHz clock from a GPSDO.
The frequency also appears to stabilise after around 45 minutes.
[cid:0acb1b9d-a986-47a3-85de-53b95bb8479e]
So far so good.
However I find that if I leave the unit running for a few hours, the frequency gradually drifts upwards by up to 0.5Hz.
That is well outside the 8663-XS specification. It is supposed to remain within 4x10^-9 from -20 to +70degC (I assume that is external ambient temp).
The OCXO temperature (as measured on the outer can) remains constant at 60 degC.
The tuning voltage and the supply voltage (12V) also remain constant.
The tuning voltage comes from a LH0070 10V precision reference and a 10 turn 10K trimmer.
I expected the tuning voltage required for 10MHz to be around 5V. The spec indicates a range of 0->10V.
I found that the tuning voltage needed to be set to just below 10V to get 10MHz.
Initially I thought that perhaps that's because it's an old used device.
Subsequent tests however make me think it's related to temperature.
I find that if I remove the equipment case lid, the frequency drifts slowly downwards.
When I replace the lid, the frequency error slowly recovers.
I assume the OCXO temperature drops slightly when the lid is removed despite it having ventilation slots directly above the OCXO.
I expected the OCXO internal temperature to be maintained to within around +/- 1degC by the heater control circuit such that it would compensate for small external temperature variations.
I am at a loss to explain what is going on and am running out of ideas.
It appears that the OCXO internal temperature regulation is not working as well as it should.
Is it just my particular device that behaves in this way or is it a common issue with this OCXO?
I don't want to buy another used device from China (around 40 GBP) only to find the same problem.
I would welcome any thoughts/suggestions from the experts here at time-nuts.
For the full story, please refer to my recent thread in the eevblog forum:-
https://www.eevblog.com/forum/projects/oscilloquartz-8663-xs-ocxo/
[cid:18711b70-068e-474b-8ab5-74e886152aa1]
Regards,
Brian.
<image.png><image.png>_______________________________________________
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The phenomenon that you see may be due to moisture absorbed/adsorbed by one or more of the components. While in storage the unit equilibrates with maybe 60% RH. When the oven is operated the RH is reduced to near zero. (Each degree C reduces RH by about 10%)
It may take weeks to settle.
Cheers
Neville Michie
Sent from my iPhone
On 28 Oct 2023, at 10:06 am, Brian K via time-nuts time-nuts@lists.febo.com wrote:
I recently constructed a homebrew 10MHz distribution amp.
It has provision for both an external 10MHz source such as a GPSDO or an internal OCXO.
For the internal OCXO I chose a used Oscilloquartz 8663-XS from China.
When I began testing the unit I discovered an issue with frequency / temperature stability.
I plotted a graph that shows the external temperature of the OCXO can as the device warms up.
It stabilises at 60degC after around 45 minutes.
I also plotted the frequency error measured using a Racal 1998 with an external 10MHz clock from a GPSDO.
The frequency also appears to stabilise after around 45 minutes.
[cid:0acb1b9d-a986-47a3-85de-53b95bb8479e]
So far so good.
However I find that if I leave the unit running for a few hours, the frequency gradually drifts upwards by up to 0.5Hz.
That is well outside the 8663-XS specification. It is supposed to remain within 4x10^-9 from -20 to +70degC (I assume that is external ambient temp).
The OCXO temperature (as measured on the outer can) remains constant at 60 degC.
The tuning voltage and the supply voltage (12V) also remain constant.
The tuning voltage comes from a LH0070 10V precision reference and a 10 turn 10K trimmer.
I expected the tuning voltage required for 10MHz to be around 5V. The spec indicates a range of 0->10V.
I found that the tuning voltage needed to be set to just below 10V to get 10MHz.
Initially I thought that perhaps that's because it's an old used device.
Subsequent tests however make me think it's related to temperature.
I find that if I remove the equipment case lid, the frequency drifts slowly downwards.
When I replace the lid, the frequency error slowly recovers.
I assume the OCXO temperature drops slightly when the lid is removed despite it having ventilation slots directly above the OCXO.
I expected the OCXO internal temperature to be maintained to within around +/- 1degC by the heater control circuit such that it would compensate for small external temperature variations.
I am at a loss to explain what is going on and am running out of ideas.
It appears that the OCXO internal temperature regulation is not working as well as it should.
Is it just my particular device that behaves in this way or is it a common issue with this OCXO?
I don't want to buy another used device from China (around 40 GBP) only to find the same problem.
I would welcome any thoughts/suggestions from the experts here at time-nuts.
For the full story, please refer to my recent thread in the eevblog forum:-
https://www.eevblog.com/forum/projects/oscilloquartz-8663-xs-ocxo/
[cid:18711b70-068e-474b-8ab5-74e886152aa1]
Regards,
Brian.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
On 10/27/2023 7:15 AM, Brian K via time-nuts wrote:
I recently constructed a homebrew 10MHz distribution amp.
It has provision for both an external 10MHz source such as a GPSDO or an internal OCXO.
For the internal OCXO I chose a used Oscilloquartz 8663-XS from China.
Brian, Sorry to say I'm pretty sure you have a faulty OCXO. I have used
several of those and the control voltage to reach 10 MHz is usually
around 5V, which can be easily achieved from the Reference V output,
which is around 8V. It looks to me like there is a fault in the
oscillator circuit inside the inner oven. Total control range should be
at least 2 Hz either side of nominal. I have one in my Shera GPSDO and
over more than two years the control voltage has crept up very slowly
due to ageing and shows a very slight diurnal variation due to room
temperature changes.
And there's no trimmer inside, the solder blob was presumably when they
filled it with whatever inert gas they used at manufacture.
Dan
"The phenomenon that you see may be due to moisture absorbed/adsorbed by one or more of the components. While in storage the unit equilibrates with maybe 60% RH. When the oven is operated the RH is reduced to near zero. (Each degree C reduces RH by about 10%)
It may take weeks to settle."
The 8663-XS can is hermetically sealed so I doubt if it is a humidity problem.
As I pointed out in the eevblog thread, there is a solder blob on the side of the can.
I suspect this seals a hole used to fill the inside with an inert gas such as dry Nitrogen.
Many years ago I worked for Marconi Instruments.
One project I worked on was a Selective Level Meter used to test analogue FDM Telecomms systems.
During environmental testing they discovered problems with crystal filter frequency response changing at high humidity.
The solution was to fit the filter inside a sealed container filled with Nitrogen.
I suspect Oscilloquartz and other OCXO manufacturers do a similar thing.
Some MTI OCXOs have a similar solder blob.
From: Neville Michie namichie@gmail.com
Sent: 28 October 2023 00:38
To: Discussion of precise time and frequency measurement time-nuts@lists.febo.com
Cc: Brian K brian_mk@hotmail.co.uk
Subject: Re: [time-nuts] Oscilloquartz 8663-XS stability problem
The phenomenon that you see may be due to moisture absorbed/adsorbed by one or more of the components. While in storage the unit equilibrates with maybe 60% RH. When the oven is operated the RH is reduced to near zero. (Each degree C reduces RH by about 10%)
It may take weeks to settle.
Cheers
Neville Michie
Sent from my iPhone
On 28 Oct 2023, at 10:06 am, Brian K via time-nuts time-nuts@lists.febo.com wrote:
I recently constructed a homebrew 10MHz distribution amp.
It has provision for both an external 10MHz source such as a GPSDO or an internal OCXO.
For the internal OCXO I chose a used Oscilloquartz 8663-XS from China.
When I began testing the unit I discovered an issue with frequency / temperature stability.
I plotted a graph that shows the external temperature of the OCXO can as the device warms up.
It stabilises at 60degC after around 45 minutes.
I also plotted the frequency error measured using a Racal 1998 with an external 10MHz clock from a GPSDO.
The frequency also appears to stabilise after around 45 minutes.
[cid:0acb1b9d-a986-47a3-85de-53b95bb8479e]
So far so good.
However I find that if I leave the unit running for a few hours, the frequency gradually drifts upwards by up to 0.5Hz.
That is well outside the 8663-XS specification. It is supposed to remain within 4x10^-9 from -20 to +70degC (I assume that is external ambient temp).
The OCXO temperature (as measured on the outer can) remains constant at 60 degC.
The tuning voltage and the supply voltage (12V) also remain constant.
The tuning voltage comes from a LH0070 10V precision reference and a 10 turn 10K trimmer.
I expected the tuning voltage required for 10MHz to be around 5V. The spec indicates a range of 0->10V.
I found that the tuning voltage needed to be set to just below 10V to get 10MHz.
Initially I thought that perhaps that's because it's an old used device.
Subsequent tests however make me think it's related to temperature.
I find that if I remove the equipment case lid, the frequency drifts slowly downwards.
When I replace the lid, the frequency error slowly recovers.
I assume the OCXO temperature drops slightly when the lid is removed despite it having ventilation slots directly above the OCXO.
I expected the OCXO internal temperature to be maintained to within around +/- 1degC by the heater control circuit such that it would compensate for small external temperature variations.
I am at a loss to explain what is going on and am running out of ideas.
It appears that the OCXO internal temperature regulation is not working as well as it should.
Is it just my particular device that behaves in this way or is it a common issue with this OCXO?
I don't want to buy another used device from China (around 40 GBP) only to find the same problem.
I would welcome any thoughts/suggestions from the experts here at time-nuts.
For the full story, please refer to my recent thread in the eevblog forum:-
https://www.eevblog.com/forum/projects/oscilloquartz-8663-xs-ocxo/
[cid:18711b70-068e-474b-8ab5-74e886152aa1]
Regards,
Brian.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
I found an old time-nuts thread that discusses whether or not the 866S-XS uses a Double Oven.
https://febo.com/pipermail/time-nuts_lists.febo.com/2020-February/099099.html
I don't know it this question was definitively answered.
I have seen AliExpress ads that include photos of a similar device where the label specifically mentions 'Double Oven'.
The part number is not quite the same - '108663-01' made by 'UCT'.
[cid:cafb73c8-a8a2-451d-a9a9-687dabff4a70]
The eevblog link below has photos of what is inside the UCT device:-
https://www.eevblog.com/forum/testgear/inside-the-uct-108663-1-10-mhz-double-oven-ocxo/msg4909163/#msg4909163
Inside the UCT 108663-1 10 MHz Double Oven OCXO - Page 1https://www.eevblog.com/forum/testgear/inside-the-uct-108663-1-10-mhz-double-oven-ocxo/msg4909163/#msg4909163
Inside the UCT 108663-1 10 MHz Double Oven OCXO - Page 1
www.eevblog.com
The device I have does not mention 'Double Oven' on the label.
The part number is simply '8663-XS' similar to that below:-
[cid:f4157cbe-4e4f-407c-af27-79eb000b771c]
The actual label on my device gives:-
Art. 945.866.302.02
Serial No. 08/03 MY 38701
From: Brian K via time-nuts time-nuts@lists.febo.com
Sent: 27 October 2023 15:15
To: time-nuts@lists.febo.com time-nuts@lists.febo.com
Cc: Brian K brian_mk@hotmail.co.uk
Subject: [time-nuts] Oscilloquartz 8663-XS stability problem
I recently constructed a homebrew 10MHz distribution amp.
It has provision for both an external 10MHz source such as a GPSDO or an internal OCXO.
For the internal OCXO I chose a used Oscilloquartz 8663-XS from China.
When I began testing the unit I discovered an issue with frequency / temperature stability.
I plotted a graph that shows the external temperature of the OCXO can as the device warms up.
It stabilises at 60degC after around 45 minutes.
I also plotted the frequency error measured using a Racal 1998 with an external 10MHz clock from a GPSDO.
The frequency also appears to stabilise after around 45 minutes.
[cid:0acb1b9d-a986-47a3-85de-53b95bb8479e]
So far so good.
However I find that if I leave the unit running for a few hours, the frequency gradually drifts upwards by up to 0.5Hz.
That is well outside the 8663-XS specification. It is supposed to remain within 4x10^-9 from -20 to +70degC (I assume that is external ambient temp).
The OCXO temperature (as measured on the outer can) remains constant at 60 degC.
The tuning voltage and the supply voltage (12V) also remain constant.
The tuning voltage comes from a LH0070 10V precision reference and a 10 turn 10K trimmer.
I expected the tuning voltage required for 10MHz to be around 5V. The spec indicates a range of 0->10V.
I found that the tuning voltage needed to be set to just below 10V to get 10MHz.
Initially I thought that perhaps that's because it's an old used device.
Subsequent tests however make me think it's related to temperature.
I find that if I remove the equipment case lid, the frequency drifts slowly downwards.
When I replace the lid, the frequency error slowly recovers.
I assume the OCXO temperature drops slightly when the lid is removed despite it having ventilation slots directly above the OCXO.
I expected the OCXO internal temperature to be maintained to within around +/- 1degC by the heater control circuit such that it would compensate for small external temperature variations.
I am at a loss to explain what is going on and am running out of ideas.
It appears that the OCXO internal temperature regulation is not working as well as it should.
Is it just my particular device that behaves in this way or is it a common issue with this OCXO?
I don't want to buy another used device from China (around 40 GBP) only to find the same problem.
I would welcome any thoughts/suggestions from the experts here at time-nuts.
For the full story, please refer to my recent thread in the eevblog forum:-
https://www.eevblog.com/forum/projects/oscilloquartz-8663-xs-ocxo/
[cid:18711b70-068e-474b-8ab5-74e886152aa1]
Regards,
Brian.
"Brian, Sorry to say I'm pretty sure you have a faulty OCXO. I have used
several of those and the control voltage to reach 10 MHz is usually
around 5V, which can be easily achieved from the Reference V output,
which is around 8V. It looks to me like there is a fault in the
oscillator circuit inside the inner oven. Total control range should be
at least 2 Hz either side of nominal. I have one in my Shera GPSDO and
over more than two years the control voltage has crept up very slowly
due to ageing and shows a very slight diurnal variation due to room
temperature changes."
Thanks Dan.
On my device, the control voltage for 10MHz sometimes does drop to somewhere between 5.5V and 7.5V.
It seems to depend on the temperature inside the equipment case.
This only becomes fully stable after the unit has been powered on for a few hours.
My guess is that the thermal inertia of the case and the hardware inside is probably quite high so it takes considerable time to stabilise.
The case has plenty of ventilation slots in the lid and the base.
The air temperature in the vicinity of the OCXO is hard to measure but I would guess something like 35->40 degC when stable (I need to recheck that).
You mention that you have an 8663-XS in your GPSDO.
Have you ever tried starting it up from cold with GPS locking disabled?
Ignoring absolute accuracy, how long does it take for the OCXO frequency to stabilise?
I wouldn't be surprised if you find a similar issue.
Brian.
From: Dan Rae via time-nuts time-nuts@lists.febo.com
Sent: 28 October 2023 02:07
To: Brian K via time-nuts time-nuts@lists.febo.com
Cc: Dan Rae danrae@verizon.net
Subject: [time-nuts] Re: Oscilloquartz 8663-XS stability problem
On 10/27/2023 7:15 AM, Brian K via time-nuts wrote:
I recently constructed a homebrew 10MHz distribution amp.
It has provision for both an external 10MHz source such as a GPSDO or an internal OCXO.
For the internal OCXO I chose a used Oscilloquartz 8663-XS from China.
And there's no trimmer inside, the solder blob was presumably when they
filled it with whatever inert gas they used at manufacture.
Dan
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
From: Dan Rae via time-nuts time-nuts@lists.febo.com
Sent: 28 October 2023 02:07
To: Brian K via time-nuts time-nuts@lists.febo.com
Cc: Dan Rae danrae@verizon.net
Subject: [time-nuts] Re: Oscilloquartz 8663-XS stability problem
On 10/27/2023 7:15 AM, Brian K via time-nuts wrote:
I recently constructed a homebrew 10MHz distribution amp.
It has provision for both an external 10MHz source such as a GPSDO or an internal OCXO.
For the internal OCXO I chose a used Oscilloquartz 8663-XS from China.
Brian, Sorry to say I'm pretty sure you have a faulty OCXO. I have used
several of those and the control voltage to reach 10 MHz is usually
around 5V, which can be easily achieved from the Reference V output,
which is around 8V. It looks to me like there is a fault in the
oscillator circuit inside the inner oven. Total control range should be
at least 2 Hz either side of nominal. I have one in my Shera GPSDO and
over more than two years the control voltage has crept up very slowly
due to ageing and shows a very slight diurnal variation due to room
temperature changes.
And there's no trimmer inside, the solder blob was presumably when they
filled it with whatever inert gas they used at manufacture.
Dan
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi
I think that the answer to the “double oven” question is that it is not one. The data sheets that have been tracked down do not make that claim. The tear downs do not show an inner oven. The device’s performance specs (and actual performance) are not in the double oven range.
It very much appears that somebody sometime somewhere claimed it was and … surprise…. it sold better. Thus folks have repeated that claim again and again. Since they are just re-selling scrap parts, they have very little knowledge about what the part is or is not. They just copy other listings for the same part.
Like any other “rumor” there is no way to stamp it out at this late date. It will just keep on being repeated until the end of time :)
Bob
On Oct 28, 2023, at 4:22 PM, Brian K via time-nuts time-nuts@lists.febo.com wrote:
I found an old time-nuts thread that discusses whether or not the 866S-XS uses a Double Oven.
https://febo.com/pipermail/time-nuts_lists.febo.com/2020-February/099099.html
I don't know it this question was definitively answered.
I have seen AliExpress ads that include photos of a similar device where the label specifically mentions 'Double Oven'.
The part number is not quite the same - '108663-01' made by 'UCT'.
[cid:cafb73c8-a8a2-451d-a9a9-687dabff4a70]
The eevblog link below has photos of what is inside the UCT device:-
https://www.eevblog.com/forum/testgear/inside-the-uct-108663-1-10-mhz-double-oven-ocxo/msg4909163/#msg4909163
Inside the UCT 108663-1 10 MHz Double Oven OCXO - Page 1https://www.eevblog.com/forum/testgear/inside-the-uct-108663-1-10-mhz-double-oven-ocxo/msg4909163/#msg4909163
Inside the UCT 108663-1 10 MHz Double Oven OCXO - Page 1
www.eevblog.com
The device I have does not mention 'Double Oven' on the label.
The part number is simply '8663-XS' similar to that below:-
[cid:f4157cbe-4e4f-407c-af27-79eb000b771c]
The actual label on my device gives:-
Art. 945.866.302.02
Serial No. 08/03 MY 38701
From: Brian K via time-nuts time-nuts@lists.febo.com
Sent: 27 October 2023 15:15
To: time-nuts@lists.febo.com time-nuts@lists.febo.com
Cc: Brian K brian_mk@hotmail.co.uk
Subject: [time-nuts] Oscilloquartz 8663-XS stability problem
I recently constructed a homebrew 10MHz distribution amp.
It has provision for both an external 10MHz source such as a GPSDO or an internal OCXO.
For the internal OCXO I chose a used Oscilloquartz 8663-XS from China.
When I began testing the unit I discovered an issue with frequency / temperature stability.
I plotted a graph that shows the external temperature of the OCXO can as the device warms up.
It stabilises at 60degC after around 45 minutes.
I also plotted the frequency error measured using a Racal 1998 with an external 10MHz clock from a GPSDO.
The frequency also appears to stabilise after around 45 minutes.
[cid:0acb1b9d-a986-47a3-85de-53b95bb8479e]
So far so good.
However I find that if I leave the unit running for a few hours, the frequency gradually drifts upwards by up to 0.5Hz.
That is well outside the 8663-XS specification. It is supposed to remain within 4x10^-9 from -20 to +70degC (I assume that is external ambient temp).
The OCXO temperature (as measured on the outer can) remains constant at 60 degC.
The tuning voltage and the supply voltage (12V) also remain constant.
The tuning voltage comes from a LH0070 10V precision reference and a 10 turn 10K trimmer.
I expected the tuning voltage required for 10MHz to be around 5V. The spec indicates a range of 0->10V.
I found that the tuning voltage needed to be set to just below 10V to get 10MHz.
Initially I thought that perhaps that's because it's an old used device.
Subsequent tests however make me think it's related to temperature.
I find that if I remove the equipment case lid, the frequency drifts slowly downwards.
When I replace the lid, the frequency error slowly recovers.
I assume the OCXO temperature drops slightly when the lid is removed despite it having ventilation slots directly above the OCXO.
I expected the OCXO internal temperature to be maintained to within around +/- 1degC by the heater control circuit such that it would compensate for small external temperature variations.
I am at a loss to explain what is going on and am running out of ideas.
It appears that the OCXO internal temperature regulation is not working as well as it should.
Is it just my particular device that behaves in this way or is it a common issue with this OCXO?
I don't want to buy another used device from China (around 40 GBP) only to find the same problem.
I would welcome any thoughts/suggestions from the experts here at time-nuts.
For the full story, please refer to my recent thread in the eevblog forum:-
https://www.eevblog.com/forum/projects/oscilloquartz-8663-xs-ocxo/
[cid:18711b70-068e-474b-8ab5-74e886152aa1]
Regards,
Brian.
<image.png><image.png>_______________________________________________
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To unsubscribe send an email to time-nuts-leave@lists.febo.com
On Sat, 28 Oct 2023 20:00:32 +0000
Brian K via time-nuts time-nuts@lists.febo.com wrote:
"The phenomenon that you see may be due to moisture absorbed/adsorbed by one or more of the components. While in storage the unit equilibrates with maybe 60% RH. When the oven is operated the RH is reduced to near zero. (Each degree C reduces RH by about 10%)
It may take weeks to settle."
The 8663-XS can is hermetically sealed so I doubt if it is a humidity problem.
As I pointed out in the eevblog thread, there is a solder blob on the side of the can.
I suspect this seals a hole used to fill the inside with an inert gas such as dry Nitrogen.
While most OCXO are hermetically sealed, it does not mean that an OCXO
bought from ebay still is. Years ago, I bought a bunch of "Trimble" OCXO,
which I suppose were relabled Vectron OC-050 or similar. I did measure
a handfull of those and most performed with decent long term stability.
But a few did not. They still kept drifting (up or down) at a rate way
beyond their spec after a month. With quite a few of them, I could see
that the glass insulator/passthrough of the pins were cracket. I.e. the
seal of the OCXO was broken. I suspect, that the OCXOs would have settled
at some point, but that could have taken months or even years and I wasn't
quite keen on measuring that long. I thought about using a drop of epoxy
to seal the cracked passthrough pins and see whether that helped, but did
not get around doing that.
On Sun, 29 Oct 2023 11:46:56 -0400
Bob Camp via time-nuts time-nuts@lists.febo.com wrote:
I think that the answer to the “double oven” question is that it is not one. The data sheets that have been tracked down do not make that claim. The tear downs do not show an inner oven. The device’s performance specs (and actual performance) are not in the double oven range.
Bob, did you find tear downs of 8663s? If so, could you send us the link?
I have been looking for those for quite some time, but never saw any.
And my google foo does not seem strong enough to find them.
Attila Kinali
--
In science if you know what you are doing you should not be doing it.
In engineering if you do not know what you are doing you should not be doing it.
-- Richard W. Hamming, The Art of Doing Science and Engineering