[time-nuts] End-of-Range: Oscilloquartz OCXO 8600-3

[Tom Knox]

Hi All;

Is the "Aging" generally related to the quartz, or other components?

Happy-Merry;

Thomas Knox



________________________________
From: time-nuts <time-nuts-bounces at febo.com> on behalf of Bob kb8tq <kb8tq at n1k.org>
Sent: Friday, December 8, 2017 9:58 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] End-of-Range: Oscilloquartz OCXO 8600-3

Hi

One risk is that the oscillator may have drifted further than one can easily adjust it by
just changing a select cap. That seems silly when we are talking about < 1 ppm, but
the 8600 is an unusual OCXO. The electrodes BVA is not your run of the mill crystal.
The “air gap” (actually a gap in vacuum) puts a pretty small capacitance in series with
the normal crystal equivalent circuit. That cuts the practical tuning range down quite
a bit….

Bob

> On Dec 8, 2017, at 11:44 AM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
>
> Hi,
>
> Many include a EFC offset pot, but when you go out of range on that, as I have for one of mine, here is no real option execept pop the lid and potentially find a cap or change a cap. I have not seen any as I recall, but should maybe take a look.
>
> However, the value for me is not to have it as sharp 5 MHz source, but very low phase noise and high stability source as reference for measurement. The offset error is less of a concern then, so that is why I have not spent quality time to fix it.
>
> Cheers,
> Magnus
>
> On 12/08/2017 04:52 PM, paul swed wrote:
>> I took a quick look at the spec sheet.
>> It appears coarse adjustment is an option M and would actually be a pot.
>> That speaks to another tuning diode for coarse? Or a pot on pot arrangement.
>> That sounds ugly.
>> Regards
>> Paul
>> WB8TSL
>> On Fri, Dec 8, 2017 at 10:17 AM, Bob kb8tq <kb8tq at n1k.org> wrote:
>>> Hi
>>>
>>> It is quite possible that nothing is actually broken and that the crystal
>>> has simply drifted
>>> outside the tuning range. It should be pretty easy to spot the coarse
>>> tuning device once
>>> the package is open. I would bet you will find a selected capacitor across
>>> the coarse tune or in
>>> series with the coarse tune. Changing the value of that cap should bring
>>> things back on
>>> frequency. I would avoid changing caps across the EFC tuning diode.
>>>
>>> Bob
>>>
>>>> On Dec 8, 2017, at 8:05 AM, Ulf Kylenfall via time-nuts <
>>> time-nuts at febo.com> wrote:
>>>>
>>>>
>>>> Gentlemen,
>>>> We have an Oscilloquartz OCXO 8600-3that cannot any longer be adjusted
>>> into 5,000,000 Hz.It is about 1 Hz out of 5 MHz and turning
>>> coarse/fineadjustment potentiometers cannot bring the frequencyinto its
>>> specification.
>>>> Oven temperature is about + 80C accordingto the thermistor and the
>>> operating voltageis at 24 VDC.
>>>> Have Googled but the only thing that turns upis datasheets w/o any
>>> details.
>>>> Before I take it apart and start lookingfor obviously broken components,
>>> isthere anyone that has a CLIP on this unit?
>>>> 73
>>>>
>>>> Ulf Kylenfall - SM6GXV
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