JD
Joe Dempster
Tue, Nov 28, 2023 3:48 PM
Vision and execution.
https://www.mdpi.com/2076-3417/13/23/12703
Joe Dempster
+1 908 413 2889 (m)
Vision and execution.
https://www.mdpi.com/2076-3417/13/23/12703
Joe Dempster
+1 908 413 2889 (m)
PK
Poul-Henning Kamp
Sat, Dec 2, 2023 3:04 PM
Joe Dempster via time-nuts writes:
I'm pretty sure this is just some kind of (under)grad assignment:
Funding
This research was funded by the Youth Innovation Promotion Association CAS, grant number: 2021409.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
--------
Joe Dempster via time-nuts writes:
> Vision and execution.
>
> https://www.mdpi.com/2076-3417/13/23/12703
I'm pretty sure this is just some kind of (under)grad assignment:
Funding
This research was funded by the Youth Innovation Promotion Association CAS, grant number: 2021409.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
JD
Joe Dempster
Sat, Dec 2, 2023 3:59 PM
Agree on the grad student angle. However, they are reporting on what looks
like a significant program.
The Eurofix comment was unusual. With the eLoran standard in the public
domain, I would think that would have more focus are extension.
Joe Dempster
+1 908 413 2889 (m)
On Sat, Dec 2, 2023 at 10:04 Poul-Henning Kamp phk@phk.freebsd.dk wrote:
Joe Dempster via time-nuts writes:
I'm pretty sure this is just some kind of (under)grad assignment:
Funding
This research was funded by the Youth Innovation Promotion
Association CAS, grant number: 2021409.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Agree on the grad student angle. However, they are reporting on what looks
like a significant program.
The Eurofix comment was unusual. With the eLoran standard in the public
domain, I would think that would have more focus are extension.
Joe Dempster
+1 908 413 2889 (m)
On Sat, Dec 2, 2023 at 10:04 Poul-Henning Kamp <phk@phk.freebsd.dk> wrote:
> --------
> Joe Dempster via time-nuts writes:
> > Vision and execution.
> >
> > https://www.mdpi.com/2076-3417/13/23/12703
>
> I'm pretty sure this is just some kind of (under)grad assignment:
>
> Funding
>
> This research was funded by the Youth Innovation Promotion
> Association CAS, grant number: 2021409.
>
> --
> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
> phk@FreeBSD.ORG | TCP/IP since RFC 956
> FreeBSD committer | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>
PK
Poul-Henning Kamp
Sat, Dec 2, 2023 4:25 PM
Agree on the grad student angle. However, they are reporting on what looks
like a significant program.
I see nothing in that paper which indicates that any kind of program exist ?
The Eurofix comment was unusual. With the eLoran standard in the public
domain, I would think that would have more focus are extension.
EuroFix is standardized under ITU, so that is merely "by the books"
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
--------
Joe Dempster writes:
> Agree on the grad student angle. However, they are reporting on what looks
> like a significant program.
I see nothing in that paper which indicates that any kind of program exist ?
> The Eurofix comment was unusual. With the eLoran standard in the public
> domain, I would think that would have more focus are extension.
EuroFix is standardized under ITU, so that is merely "by the books"
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
PS
paul swed
Mon, Dec 4, 2023 3:24 PM
Good morning to the group.
I did reread the paper carefully and with some historical interest they
seem to swap LORAN C and eLORAN early in the paper.
But that said China is re-leveraging the LORAN C towers they had for at
least Western China. They need to build 3 stations in Eastern China for
coverage in that area.
As mentioned they seem to be using Eurofix for data transmission.
It was an interesting read.
In the US the longest eLORAN test is still running. It may extend beyond
the end of the year. But unfortunately for me and the East Coast I have
never received the stations in the west that are operating. There are SDR
stations around Canada and the US and on those sites I do hear the stations.
Regards
Paul
WB8TSL
On Sat, Dec 2, 2023 at 11:45 AM Poul-Henning Kamp via time-nuts <
time-nuts@lists.febo.com> wrote:
Agree on the grad student angle. However, they are reporting on what
like a significant program.
I see nothing in that paper which indicates that any kind of program exist
?
The Eurofix comment was unusual. With the eLoran standard in the public
domain, I would think that would have more focus are extension.
EuroFix is standardized under ITU, so that is merely "by the books"
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Good morning to the group.
I did reread the paper carefully and with some historical interest they
seem to swap LORAN C and eLORAN early in the paper.
But that said China is re-leveraging the LORAN C towers they had for at
least Western China. They need to build 3 stations in Eastern China for
coverage in that area.
As mentioned they seem to be using Eurofix for data transmission.
It was an interesting read.
In the US the longest eLORAN test is still running. It may extend beyond
the end of the year. But unfortunately for me and the East Coast I have
never received the stations in the west that are operating. There are SDR
stations around Canada and the US and on those sites I do hear the stations.
Regards
Paul
WB8TSL
On Sat, Dec 2, 2023 at 11:45 AM Poul-Henning Kamp via time-nuts <
time-nuts@lists.febo.com> wrote:
> --------
> Joe Dempster writes:
>
> > Agree on the grad student angle. However, they are reporting on what
> looks
> > like a significant program.
>
> I see nothing in that paper which indicates that any kind of program exist
> ?
>
> > The Eurofix comment was unusual. With the eLoran standard in the public
> > domain, I would think that would have more focus are extension.
>
> EuroFix is standardized under ITU, so that is merely "by the books"
>
>
> --
> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
> phk@FreeBSD.ORG | TCP/IP since RFC 956
> FreeBSD committer | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>
GE
glen english LIST
Tue, Dec 5, 2023 2:42 AM
After some commentary, please:
I built some 98.304 MHz 5th overtone oscillators, the crystals have a 60
deg C turning point, they're kept close to that temp and varactors pull
it around.
It's a reference for a UHF PLL. However I am having difficulty with a
well reproducable production configuration and pulling. Pulling too much
and I see spurious modes.
I've now considered driving temperature on the crystal to pull it
around also , and back off the amount of varactor pull. IE a hybrid of
the two approaches.
I've considered now going back to 49.152 reference and using a 16.384
fundamental crystal in an harmonic oscillator configuration (x3) , or a
tripler, which results in a bit of subharmonic contribution- not really
desirable but I could put an idler/diplexor on that and then kill the
subharmonic component.
or using a 3rd overtone 49.152 crystal. I never had problems with the
spurious modes in the old days wildly pulling 3rd overtone 35 meg xtals.
The pulling requirement needs to cover it for 10 years of aging.
Presumably I can ask the crystal mfr to put more years on it to reduce
aging.
Comments please ?
with many thanks - glen.
On 29/11/2023 2:48 am, Joe Dempster via time-nuts wrote:
After some commentary, please:
I built some 98.304 MHz 5th overtone oscillators, the crystals have a 60
deg C turning point, they're kept close to that temp and varactors pull
it around.
It's a reference for a UHF PLL. However I am having difficulty with a
well reproducable production configuration and pulling. Pulling too much
and I see spurious modes.
I've now considered driving temperature on the crystal to pull it
around also , and back off the amount of varactor pull. IE a hybrid of
the two approaches.
I've considered now going back to 49.152 reference and using a 16.384
fundamental crystal in an harmonic oscillator configuration (x3) , or a
tripler, which results in a bit of subharmonic contribution- not really
desirable but I could put an idler/diplexor on that and then kill the
subharmonic component.
or using a 3rd overtone 49.152 crystal. I never had problems with the
spurious modes in the old days wildly pulling 3rd overtone 35 meg xtals.
The pulling requirement needs to cover it for 10 years of aging.
Presumably I can ask the crystal mfr to put more years on it to reduce
aging.
Comments please ?
with many thanks - glen.
On 29/11/2023 2:48 am, Joe Dempster via time-nuts wrote:
BK
Bob kb8tq
Thu, Dec 7, 2023 2:40 AM
Hi
The simple answer is that a wide pull ( = enough to cover 10 years aging) 5th overtone is a bit of a complicated design. It can be done, but the circuits (and the designs behind them) are all a bit obscure / insane.
I’d suggest that a 3rd overtone 98.304 might be another choice.
Bob
On Dec 4, 2023, at 9:42 PM, glen english LIST via time-nuts time-nuts@lists.febo.com wrote:
After some commentary, please:
I built some 98.304 MHz 5th overtone oscillators, the crystals have a 60 deg C turning point, they're kept close to that temp and varactors pull it around.
It's a reference for a UHF PLL. However I am having difficulty with a well reproducable production configuration and pulling. Pulling too much and I see spurious modes.
I've now considered driving temperature on the crystal to pull it around also , and back off the amount of varactor pull. IE a hybrid of the two approaches.
I've considered now going back to 49.152 reference and using a 16.384 fundamental crystal in an harmonic oscillator configuration (x3) , or a tripler, which results in a bit of subharmonic contribution- not really desirable but I could put an idler/diplexor on that and then kill the subharmonic component.
or using a 3rd overtone 49.152 crystal. I never had problems with the spurious modes in the old days wildly pulling 3rd overtone 35 meg xtals.
The pulling requirement needs to cover it for 10 years of aging. Presumably I can ask the crystal mfr to put more years on it to reduce aging.
Comments please ?
with many thanks - glen.
On 29/11/2023 2:48 am, Joe Dempster via time-nuts wrote:
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi
The simple answer is that a wide pull ( = enough to cover 10 years aging) 5th overtone is a bit of a complicated design. It can be done, but the circuits (and the designs behind them) are all a bit obscure / insane.
I’d suggest that a 3rd overtone 98.304 might be another choice.
Bob
> On Dec 4, 2023, at 9:42 PM, glen english LIST via time-nuts <time-nuts@lists.febo.com> wrote:
>
> After some commentary, please:
>
> I built some 98.304 MHz 5th overtone oscillators, the crystals have a 60 deg C turning point, they're kept close to that temp and varactors pull it around.
>
> It's a reference for a UHF PLL. However I am having difficulty with a well reproducable production configuration and pulling. Pulling too much and I see spurious modes.
>
> I've now considered driving temperature on the crystal to pull it around also , and back off the amount of varactor pull. IE a hybrid of the two approaches.
>
> I've considered now going back to 49.152 reference and using a 16.384 fundamental crystal in an harmonic oscillator configuration (x3) , or a tripler, which results in a bit of subharmonic contribution- not really desirable but I could put an idler/diplexor on that and then kill the subharmonic component.
>
> or using a 3rd overtone 49.152 crystal. I never had problems with the spurious modes in the old days wildly pulling 3rd overtone 35 meg xtals.
>
> The pulling requirement needs to cover it for 10 years of aging. Presumably I can ask the crystal mfr to put more years on it to reduce aging.
>
> Comments please ?
>
> with many thanks - glen.
>
> On 29/11/2023 2:48 am, Joe Dempster via time-nuts wrote:
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
GE
glen english LIST
Thu, Dec 7, 2023 5:20 AM
Hi Bob
thanks for the comment. I had similar problems with 3OT, also, which I
got a bunch made of by Kystally. They were quite good but pulling for
10-15 years seems difficult.
I'll read up on pre aging them a bit more, maybe the aging I see can
be reduced. and talk to the mfr. The inductor I used needs a tweak I
find, but its also a bit hard to know precisely, because the xtals I
have have not aged yet- IE I'm just pulling them off their original cal
frequency.
Either a 16 to 24 MHz fundamental crystal multiplied up, or the OT
crystal easily meet my phase noise objectives. Using a 16 or 24 meg
fundamental crystalk, pulling the hell out of that is fine.....Although
at the extremes, I can detect some frequency tuning hysteresis and lack
of mototonicity so there are limits. and a lack of monotonicity will
drive a loop crazy.
-glen
On 7/12/2023 1:40 pm, Bob kb8tq wrote:
Hi
The simple answer is that a wide pull ( = enough to cover 10 years aging) 5th overtone is a bit of a complicated design. It can be done, but the circuits (and the designs behind them) are all a bit obscure / insane.
I’d suggest that a 3rd overtone 98.304 might be another choice.
Bob
On Dec 4, 2023, at 9:42 PM, glen english LIST via time-nuts time-nuts@lists.febo.com wrote:
After some commentary, please:
I built some 98.304 MHz 5th overtone oscillators, the crystals have a 60 deg C turning point, they're kept close to that temp and varactors pull it around.
It's a reference for a UHF PLL. However I am having difficulty with a well reproducable production configuration and pulling. Pulling too much and I see spurious modes.
I've now considered driving temperature on the crystal to pull it around also , and back off the amount of varactor pull. IE a hybrid of the two approaches.
I've considered now going back to 49.152 reference and using a 16.384 fundamental crystal in an harmonic oscillator configuration (x3) , or a tripler, which results in a bit of subharmonic contribution- not really desirable but I could put an idler/diplexor on that and then kill the subharmonic component.
or using a 3rd overtone 49.152 crystal. I never had problems with the spurious modes in the old days wildly pulling 3rd overtone 35 meg xtals.
The pulling requirement needs to cover it for 10 years of aging. Presumably I can ask the crystal mfr to put more years on it to reduce aging.
Comments please ?
with many thanks - glen.
On 29/11/2023 2:48 am, Joe Dempster via time-nuts wrote:
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi Bob
thanks for the comment. I had similar problems with 3OT, also, which I
got a bunch made of by Kystally. They were quite good but pulling for
10-15 years seems difficult.
I'll read up on pre aging them a bit more, maybe the aging I see can
be reduced. and talk to the mfr. The inductor I used needs a tweak I
find, but its also a bit hard to know precisely, because the xtals I
have have not aged yet- IE I'm just pulling them off their original cal
frequency.
Either a 16 to 24 MHz fundamental crystal multiplied up, or the OT
crystal easily meet my phase noise objectives. Using a 16 or 24 meg
fundamental crystalk, pulling the hell out of that is fine.....Although
at the extremes, I can detect some frequency tuning hysteresis and lack
of mototonicity so there are limits. and a lack of monotonicity will
drive a loop crazy.
-glen
On 7/12/2023 1:40 pm, Bob kb8tq wrote:
> Hi
>
> The simple answer is that a wide pull ( = enough to cover 10 years aging) 5th overtone is a bit of a complicated design. It can be done, but the circuits (and the designs behind them) are all a bit obscure / insane.
>
> I’d suggest that a 3rd overtone 98.304 might be another choice.
>
> Bob
>
>> On Dec 4, 2023, at 9:42 PM, glen english LIST via time-nuts <time-nuts@lists.febo.com> wrote:
>>
>> After some commentary, please:
>>
>> I built some 98.304 MHz 5th overtone oscillators, the crystals have a 60 deg C turning point, they're kept close to that temp and varactors pull it around.
>>
>> It's a reference for a UHF PLL. However I am having difficulty with a well reproducable production configuration and pulling. Pulling too much and I see spurious modes.
>>
>> I've now considered driving temperature on the crystal to pull it around also , and back off the amount of varactor pull. IE a hybrid of the two approaches.
>>
>> I've considered now going back to 49.152 reference and using a 16.384 fundamental crystal in an harmonic oscillator configuration (x3) , or a tripler, which results in a bit of subharmonic contribution- not really desirable but I could put an idler/diplexor on that and then kill the subharmonic component.
>>
>> or using a 3rd overtone 49.152 crystal. I never had problems with the spurious modes in the old days wildly pulling 3rd overtone 35 meg xtals.
>>
>> The pulling requirement needs to cover it for 10 years of aging. Presumably I can ask the crystal mfr to put more years on it to reduce aging.
>>
>> Comments please ?
>>
>> with many thanks - glen.
>>
>> On 29/11/2023 2:48 am, Joe Dempster via time-nuts wrote:
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
JH
john.haine@haine-online.net
Thu, Dec 7, 2023 11:53 AM
Might be easier to add an extra stage of frequency division and use a lower frequency non-overtone crystal? There was a neat little circuit invented years ago by Racal that gave a way to digitally insert very small frequency increments, I believe to permit "digital pulling" of a reference oscillator.
-----Original Message-----
From: Bob kb8tq via time-nuts time-nuts@lists.febo.com
Sent: Thursday, December 7, 2023 2:40 AM
To: glenlist@cortexrf.com.au; Discussion of precise time and frequency measurement time-nuts@lists.febo.com
Cc: Bob kb8tq kb8tq@n1k.org
Subject: [time-nuts] Re: pulling some crystals
Hi
The simple answer is that a wide pull ( = enough to cover 10 years aging) 5th overtone is a bit of a complicated design. It can be done, but the circuits (and the designs behind them) are all a bit obscure / insane.
I’d suggest that a 3rd overtone 98.304 might be another choice.
Bob
On Dec 4, 2023, at 9:42 PM, glen english LIST via time-nuts time-nuts@lists.febo.com wrote:
After some commentary, please:
I built some 98.304 MHz 5th overtone oscillators, the crystals have a 60 deg C turning point, they're kept close to that temp and varactors pull it around.
It's a reference for a UHF PLL. However I am having difficulty with a well reproducable production configuration and pulling. Pulling too much and I see spurious modes.
I've now considered driving temperature on the crystal to pull it around also , and back off the amount of varactor pull. IE a hybrid of the two approaches.
I've considered now going back to 49.152 reference and using a 16.384 fundamental crystal in an harmonic oscillator configuration (x3) , or a tripler, which results in a bit of subharmonic contribution- not really desirable but I could put an idler/diplexor on that and then kill the subharmonic component.
or using a 3rd overtone 49.152 crystal. I never had problems with the spurious modes in the old days wildly pulling 3rd overtone 35 meg xtals.
The pulling requirement needs to cover it for 10 years of aging. Presumably I can ask the crystal mfr to put more years on it to reduce aging.
Comments please ?
with many thanks - glen.
On 29/11/2023 2:48 am, Joe Dempster via time-nuts wrote:
time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send
an email to time-nuts-leave@lists.febo.com
Might be easier to add an extra stage of frequency division and use a lower frequency non-overtone crystal? There was a neat little circuit invented years ago by Racal that gave a way to digitally insert very small frequency increments, I believe to permit "digital pulling" of a reference oscillator.
-----Original Message-----
From: Bob kb8tq via time-nuts <time-nuts@lists.febo.com>
Sent: Thursday, December 7, 2023 2:40 AM
To: glenlist@cortexrf.com.au; Discussion of precise time and frequency measurement <time-nuts@lists.febo.com>
Cc: Bob kb8tq <kb8tq@n1k.org>
Subject: [time-nuts] Re: pulling some crystals
Hi
The simple answer is that a wide pull ( = enough to cover 10 years aging) 5th overtone is a bit of a complicated design. It can be done, but the circuits (and the designs behind them) are all a bit obscure / insane.
I’d suggest that a 3rd overtone 98.304 might be another choice.
Bob
> On Dec 4, 2023, at 9:42 PM, glen english LIST via time-nuts <time-nuts@lists.febo.com> wrote:
>
> After some commentary, please:
>
> I built some 98.304 MHz 5th overtone oscillators, the crystals have a 60 deg C turning point, they're kept close to that temp and varactors pull it around.
>
> It's a reference for a UHF PLL. However I am having difficulty with a well reproducable production configuration and pulling. Pulling too much and I see spurious modes.
>
> I've now considered driving temperature on the crystal to pull it around also , and back off the amount of varactor pull. IE a hybrid of the two approaches.
>
> I've considered now going back to 49.152 reference and using a 16.384 fundamental crystal in an harmonic oscillator configuration (x3) , or a tripler, which results in a bit of subharmonic contribution- not really desirable but I could put an idler/diplexor on that and then kill the subharmonic component.
>
> or using a 3rd overtone 49.152 crystal. I never had problems with the spurious modes in the old days wildly pulling 3rd overtone 35 meg xtals.
>
> The pulling requirement needs to cover it for 10 years of aging. Presumably I can ask the crystal mfr to put more years on it to reduce aging.
>
> Comments please ?
>
> with many thanks - glen.
>
> On 29/11/2023 2:48 am, Joe Dempster via time-nuts wrote:
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send
> an email to time-nuts-leave@lists.febo.com
_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com
BK
Bob kb8tq
Thu, Dec 7, 2023 3:16 PM
Hi
How much aging are you trying to compensate for?
If you are expecting 5 ppm per year / every year for 10 years = 50 ppm then you are out of luck. If you are looking at 1 ppm first year and 5 ppm over 10 years, that’s a very different target.
The best way to work this out is to measure the aging rate on the oscillator for a few months. That way you also “see” any issues with other parts in the circuit.
Bob
On Dec 7, 2023, at 12:20 AM, glen english LIST glenlist@cortexrf.com.au wrote:
Hi Bob
thanks for the comment. I had similar problems with 3OT, also, which I got a bunch made of by Kystally. They were quite good but pulling for 10-15 years seems difficult.
I'll read up on pre aging them a bit more, maybe the aging I see can be reduced. and talk to the mfr. The inductor I used needs a tweak I find, but its also a bit hard to know precisely, because the xtals I have have not aged yet- IE I'm just pulling them off their original cal frequency.
Either a 16 to 24 MHz fundamental crystal multiplied up, or the OT crystal easily meet my phase noise objectives. Using a 16 or 24 meg fundamental crystalk, pulling the hell out of that is fine.....Although at the extremes, I can detect some frequency tuning hysteresis and lack of mototonicity so there are limits. and a lack of monotonicity will drive a loop crazy.
-glen
On 7/12/2023 1:40 pm, Bob kb8tq wrote:
Hi
The simple answer is that a wide pull ( = enough to cover 10 years aging) 5th overtone is a bit of a complicated design. It can be done, but the circuits (and the designs behind them) are all a bit obscure / insane.
I’d suggest that a 3rd overtone 98.304 might be another choice.
Bob
On Dec 4, 2023, at 9:42 PM, glen english LIST via time-nuts time-nuts@lists.febo.com wrote:
After some commentary, please:
I built some 98.304 MHz 5th overtone oscillators, the crystals have a 60 deg C turning point, they're kept close to that temp and varactors pull it around.
It's a reference for a UHF PLL. However I am having difficulty with a well reproducable production configuration and pulling. Pulling too much and I see spurious modes.
I've now considered driving temperature on the crystal to pull it around also , and back off the amount of varactor pull. IE a hybrid of the two approaches.
I've considered now going back to 49.152 reference and using a 16.384 fundamental crystal in an harmonic oscillator configuration (x3) , or a tripler, which results in a bit of subharmonic contribution- not really desirable but I could put an idler/diplexor on that and then kill the subharmonic component.
or using a 3rd overtone 49.152 crystal. I never had problems with the spurious modes in the old days wildly pulling 3rd overtone 35 meg xtals.
The pulling requirement needs to cover it for 10 years of aging. Presumably I can ask the crystal mfr to put more years on it to reduce aging.
Comments please ?
with many thanks - glen.
On 29/11/2023 2:48 am, Joe Dempster via time-nuts wrote:
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi
How much aging are you trying to compensate for?
If you are expecting 5 ppm per year / every year for 10 years = 50 ppm then you are out of luck. If you are looking at 1 ppm first year and 5 ppm over 10 years, that’s a very different target.
The best way to work this out is to measure the aging rate on the oscillator for a few months. That way you also “see” any issues with other parts in the circuit.
Bob
> On Dec 7, 2023, at 12:20 AM, glen english LIST <glenlist@cortexrf.com.au> wrote:
>
> Hi Bob
>
> thanks for the comment. I had similar problems with 3OT, also, which I got a bunch made of by Kystally. They were quite good but pulling for 10-15 years seems difficult.
>
> I'll read up on pre aging them a bit more, maybe the aging I see can be reduced. and talk to the mfr. The inductor I used needs a tweak I find, but its also a bit hard to know precisely, because the xtals I have have not aged yet- IE I'm just pulling them off their original cal frequency.
>
> Either a 16 to 24 MHz fundamental crystal multiplied up, or the OT crystal easily meet my phase noise objectives. Using a 16 or 24 meg fundamental crystalk, pulling the hell out of that is fine.....Although at the extremes, I can detect some frequency tuning hysteresis and lack of mototonicity so there are limits. and a lack of monotonicity will drive a loop crazy.
>
> -glen
>
>
> On 7/12/2023 1:40 pm, Bob kb8tq wrote:
>> Hi
>>
>> The simple answer is that a wide pull ( = enough to cover 10 years aging) 5th overtone is a bit of a complicated design. It can be done, but the circuits (and the designs behind them) are all a bit obscure / insane.
>>
>> I’d suggest that a 3rd overtone 98.304 might be another choice.
>>
>> Bob
>>
>>> On Dec 4, 2023, at 9:42 PM, glen english LIST via time-nuts <time-nuts@lists.febo.com> wrote:
>>>
>>> After some commentary, please:
>>>
>>> I built some 98.304 MHz 5th overtone oscillators, the crystals have a 60 deg C turning point, they're kept close to that temp and varactors pull it around.
>>>
>>> It's a reference for a UHF PLL. However I am having difficulty with a well reproducable production configuration and pulling. Pulling too much and I see spurious modes.
>>>
>>> I've now considered driving temperature on the crystal to pull it around also , and back off the amount of varactor pull. IE a hybrid of the two approaches.
>>>
>>> I've considered now going back to 49.152 reference and using a 16.384 fundamental crystal in an harmonic oscillator configuration (x3) , or a tripler, which results in a bit of subharmonic contribution- not really desirable but I could put an idler/diplexor on that and then kill the subharmonic component.
>>>
>>> or using a 3rd overtone 49.152 crystal. I never had problems with the spurious modes in the old days wildly pulling 3rd overtone 35 meg xtals.
>>>
>>> The pulling requirement needs to cover it for 10 years of aging. Presumably I can ask the crystal mfr to put more years on it to reduce aging.
>>>
>>> Comments please ?
>>>
>>> with many thanks - glen.
>>>
>>> On 29/11/2023 2:48 am, Joe Dempster via time-nuts wrote:
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