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

[Magnus Danielson]

Hi,

The unloaded Q is above 3 million, which is another way to measure how 
unusual these are.

If I had schematics I would be more inclined to do something.

Cheers,
Magnus

On 12/08/2017 05:58 PM, Bob kb8tq wrote:
> 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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