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

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

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

My HP-103AR frequency standard has a similar problem. I have been advised to take it apart and replace one of the capacitors in order to bring the frequency back into the range of adjustment. Sounds like you have the same problem. Jeremy On Fri, Dec 8, 2017 at 7:52 AM paul swed <paulswedb@gmail.com> 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@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@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 > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@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@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@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Sent from my iPad 4.

I have also done this to older oscillators and it works. When you look at the caps in the unit, if you are lucky somehow you may be able to see what type they are. Yes silver mica but there are various qualities and tempco's. Try to match the quality if at all possible. Otherwise guess. Good luck and its not the worst issue you will run into. Just maybe thats why you obtained the oscillator in the first place. Hey bad stuff is my friend. Regards Paul WB8TSL On Fri, Dec 8, 2017 at 11:31 AM, Jeremy Nichols <jn6wfo@gmail.com> wrote: > My HP-103AR frequency standard has a similar problem. I have been advised > to take it apart and replace one of the capacitors in order to bring the > frequency back into the range of adjustment. Sounds like you have the same > problem. > > Jeremy > > > On Fri, Dec 8, 2017 at 7:52 AM paul swed <paulswedb@gmail.com> 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@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@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 > > > > _______________________________________________ > > > > time-nuts mailing list -- time-nuts@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@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@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > -- > Sent from my iPad 4. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. >

Hi These days there is really no reason at all to play with silver mica caps in an oscillator. A very normal ceramic NPO will do just as well. It also will be cheaper / easier to find. If you want to go exotic, go for glass or porcelain caps. It is pretty unlikely you will find them in a surplus OCXO. No real need to stock them up as spares ….. Bob > On Dec 8, 2017, at 11:38 AM, paul swed <paulswedb@gmail.com> wrote: > > I have also done this to older oscillators and it works. > When you look at the caps in the unit, if you are lucky somehow you may be > able to see what type they are. > Yes silver mica but there are various qualities and tempco's. > Try to match the quality if at all possible. > Otherwise guess. > Good luck and its not the worst issue you will run into. > Just maybe thats why you obtained the oscillator in the first place. > Hey bad stuff is my friend. > Regards > Paul > WB8TSL > > On Fri, Dec 8, 2017 at 11:31 AM, Jeremy Nichols <jn6wfo@gmail.com> wrote: > >> My HP-103AR frequency standard has a similar problem. I have been advised >> to take it apart and replace one of the capacitors in order to bring the >> frequency back into the range of adjustment. Sounds like you have the same >> problem. >> >> Jeremy >> >> >> On Fri, Dec 8, 2017 at 7:52 AM paul swed <paulswedb@gmail.com> 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@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@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 >>>>> _______________________________________________ >>>>> time-nuts mailing list -- time-nuts@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@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@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> -- >> Sent from my iPad 4. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@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@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

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

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

Hi All; Is the "Aging" generally related to the quartz, or other components? Happy-Merry; Thomas Knox ________________________________ From: time-nuts <time-nuts-bounces@febo.com> on behalf of Bob kb8tq <kb8tq@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@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@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@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 >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@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@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@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts time-nuts Info Page - American Febo Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> www.febo.com time-nuts is a low volume, high SNR list for the discussion of precise time and frequency measurement and related topics. To see the collection of prior postings to ... >> and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts time-nuts Info Page - American Febo Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> www.febo.com time-nuts is a low volume, high SNR list for the discussion of precise time and frequency measurement and related topics. To see the collection of prior postings to ... > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts time-nuts Info Page - American Febo Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> www.febo.com time-nuts is a low volume, high SNR list for the discussion of precise time and frequency measurement and related topics. To see the collection of prior postings to ... and follow the instructions there.

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