Empathy List Archives

MU

Michael Ulbrich

Sun, Nov 20, 2016 11:49 PM

Hi there,

I'm new to this list and have some interest in quartz crystal and
rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-)

I snatched an R&S XSD frequency standard accompanied by an XKE frequency
controller. Found the manuals on KO4BB's site (Thanks a lot for that!
BTW there's a slight mix-up of pages in that some of the XKE pages have
found their way into the XSD manual).

My initial hope of a quick and easy restoration project faded a bit when
I looked at the XSD output frequency after heating up the oven. It was
off by about -1 * 10-5 and after cranking the fine tuning for some time
and having another look at the specs I realized that the frequency was
too far off to be dialed in by the fine tuning which only covers about
+/- 2 * 10-7.

Next step was to take apart the oven and check series capacitor,
oscillator and the crystal itself. I found that even the coarse
adjustment range of the cylindrical series capacitor (40 - 110 pF) would
not allow to pull the crystal to it's specified frequency. When
replacing the series cap by a ceramic and lowering the value to just
before the oscillation breaks down (about 10 pF) I managed to set the
oscillator frequency offset to +2.5 * 10-6 at room temperature. But
even this will not suffice when taking into account that the frequency
will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up
to its operating temperature. I also checked some of the components on
the oscillator PCB which might have an influence on frequency but could
not find any fault.

The crystal itself is a disk of about 30 mm diameter mounted in a sealed
glass cylinder of about 38 mm dia. and 43 mm height. There is no socket
just 2 bare wires.. It does not show any visual signs of damage.
According to a reference given in the R&S XSD manual the crystal's
construction follows a publication from A.W. Warner "Design and
Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39,
Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that
it is an AT-cut 5th overtone design.

Now my questions:

a) Considering that this gear is about 50 years old, a "crystal gone
bad" situation shouldn't be that much of a surprise, right? But could
there be any other cause of the "huge" frequency offset besides a bad
crystal? I would very much appreciate any idea that I could try to get
this baby back on spec.

b) if nothing else helps: Could any of you give me a hint about who
might be able to supply a spare crystal? I tried my directly reachable
contacts but unfortunately to no avail so far. Please consider that
similar crystals might also have found their way into other
manufacturer's constructions from that era - Sulzer, Racal, HP ... you
name it ...

Many thanks in advance!

Best regards ... Michael U.

Hi there, I'm new to this list and have some interest in quartz crystal and rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-) I snatched an R&S XSD frequency standard accompanied by an XKE frequency controller. Found the manuals on KO4BB's site (Thanks a lot for that! BTW there's a slight mix-up of pages in that some of the XKE pages have found their way into the XSD manual). My initial hope of a quick and easy restoration project faded a bit when I looked at the XSD output frequency after heating up the oven. It was off by about -1 * 10-5 and after cranking the fine tuning for some time and having another look at the specs I realized that the frequency was too far off to be dialed in by the fine tuning which only covers about +/- 2 * 10-7. Next step was to take apart the oven and check series capacitor, oscillator and the crystal itself. I found that even the coarse adjustment range of the cylindrical series capacitor (40 - 110 pF) would not allow to pull the crystal to it's specified frequency. When replacing the series cap by a ceramic and lowering the value to just before the oscillation breaks down (about 10 pF) I managed to set the oscillator frequency offset to +2.5 * 10-6 at room temperature. But even this will not suffice when taking into account that the frequency will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up to its operating temperature. I also checked some of the components on the oscillator PCB which might have an influence on frequency but could not find any fault. The crystal itself is a disk of about 30 mm diameter mounted in a sealed glass cylinder of about 38 mm dia. and 43 mm height. There is no socket just 2 bare wires.. It does not show any visual signs of damage. According to a reference given in the R&S XSD manual the crystal's construction follows a publication from A.W. Warner "Design and Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39, Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that it is an AT-cut 5th overtone design. Now my questions: a) Considering that this gear is about 50 years old, a "crystal gone bad" situation shouldn't be that much of a surprise, right? But could there be any other cause of the "huge" frequency offset besides a bad crystal? I would very much appreciate any idea that I could try to get this baby back on spec. b) if nothing else helps: Could any of you give me a hint about who might be able to supply a spare crystal? I tried my directly reachable contacts but unfortunately to no avail so far. Please consider that similar crystals might also have found their way into other manufacturer's constructions from that era - Sulzer, Racal, HP ... you name it ... Many thanks in advance! Best regards ... Michael U.

AM

Alan Melia

Mon, Nov 21, 2016 1:00 AM

Michael a couple of wild thoughts, make sure there is no 500kHz there (this
is the crystal fundamental and the maintaining circuit should be
degenerative there. (Is it a Meecham Bridge?)

That sounds like a baseless IO GT valve (tube in US ) enclosure which was
probably originally evacuated....has the vacuum gone soft in 50 years?....I
dont know how you would check, but I think that would cause a lowering of
the frequency.

Alan
G3NYK

----- Original Message -----
From: "Michael Ulbrich" mul@rentapacs.de
To: "Time-Nuts" time-nuts@febo.com
Sent: Sunday, November 20, 2016 11:49 PM
Subject: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad?

Hi there,

I'm new to this list and have some interest in quartz crystal and
rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-)

I snatched an R&S XSD frequency standard accompanied by an XKE frequency
controller. Found the manuals on KO4BB's site (Thanks a lot for that!
BTW there's a slight mix-up of pages in that some of the XKE pages have
found their way into the XSD manual).

My initial hope of a quick and easy restoration project faded a bit when
I looked at the XSD output frequency after heating up the oven. It was
off by about -1 * 10-5 and after cranking the fine tuning for some time
and having another look at the specs I realized that the frequency was
too far off to be dialed in by the fine tuning which only covers about
+/- 2 * 10-7.

Next step was to take apart the oven and check series capacitor,
oscillator and the crystal itself. I found that even the coarse
adjustment range of the cylindrical series capacitor (40 - 110 pF) would
not allow to pull the crystal to it's specified frequency. When
replacing the series cap by a ceramic and lowering the value to just
before the oscillation breaks down (about 10 pF) I managed to set the
oscillator frequency offset to +2.5 * 10-6 at room temperature. But
even this will not suffice when taking into account that the frequency
will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up
to its operating temperature. I also checked some of the components on
the oscillator PCB which might have an influence on frequency but could
not find any fault.

The crystal itself is a disk of about 30 mm diameter mounted in a sealed
glass cylinder of about 38 mm dia. and 43 mm height. There is no socket
just 2 bare wires.. It does not show any visual signs of damage.
According to a reference given in the R&S XSD manual the crystal's
construction follows a publication from A.W. Warner "Design and
Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39,
Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that
it is an AT-cut 5th overtone design.

Now my questions:

a) Considering that this gear is about 50 years old, a "crystal gone
bad" situation shouldn't be that much of a surprise, right? But could
there be any other cause of the "huge" frequency offset besides a bad
crystal? I would very much appreciate any idea that I could try to get
this baby back on spec.

b) if nothing else helps: Could any of you give me a hint about who
might be able to supply a spare crystal? I tried my directly reachable
contacts but unfortunately to no avail so far. Please consider that
similar crystals might also have found their way into other
manufacturer's constructions from that era - Sulzer, Racal, HP ... you
name it ...

Many thanks in advance!

Best regards ... Michael U.

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.

Michael a couple of wild thoughts, make sure there is no 500kHz there (this is the crystal fundamental and the maintaining circuit should be degenerative there. (Is it a Meecham Bridge?) That sounds like a baseless IO GT valve (tube in US ) enclosure which was probably originally evacuated....has the vacuum gone soft in 50 years?....I dont know how you would check, but I think that would cause a lowering of the frequency. Alan G3NYK ----- Original Message ----- From: "Michael Ulbrich" <mul@rentapacs.de> To: "Time-Nuts" <time-nuts@febo.com> Sent: Sunday, November 20, 2016 11:49 PM Subject: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad? > Hi there, > > I'm new to this list and have some interest in quartz crystal and > rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-) > > I snatched an R&S XSD frequency standard accompanied by an XKE frequency > controller. Found the manuals on KO4BB's site (Thanks a lot for that! > BTW there's a slight mix-up of pages in that some of the XKE pages have > found their way into the XSD manual). > > My initial hope of a quick and easy restoration project faded a bit when > I looked at the XSD output frequency after heating up the oven. It was > off by about -1 * 10-5 and after cranking the fine tuning for some time > and having another look at the specs I realized that the frequency was > too far off to be dialed in by the fine tuning which only covers about > +/- 2 * 10-7. > > Next step was to take apart the oven and check series capacitor, > oscillator and the crystal itself. I found that even the coarse > adjustment range of the cylindrical series capacitor (40 - 110 pF) would > not allow to pull the crystal to it's specified frequency. When > replacing the series cap by a ceramic and lowering the value to just > before the oscillation breaks down (about 10 pF) I managed to set the > oscillator frequency offset to +2.5 * 10-6 at room temperature. But > even this will not suffice when taking into account that the frequency > will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up > to its operating temperature. I also checked some of the components on > the oscillator PCB which might have an influence on frequency but could > not find any fault. > > The crystal itself is a disk of about 30 mm diameter mounted in a sealed > glass cylinder of about 38 mm dia. and 43 mm height. There is no socket > just 2 bare wires.. It does not show any visual signs of damage. > According to a reference given in the R&S XSD manual the crystal's > construction follows a publication from A.W. Warner "Design and > Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39, > Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that > it is an AT-cut 5th overtone design. > > Now my questions: > > a) Considering that this gear is about 50 years old, a "crystal gone > bad" situation shouldn't be that much of a surprise, right? But could > there be any other cause of the "huge" frequency offset besides a bad > crystal? I would very much appreciate any idea that I could try to get > this baby back on spec. > > b) if nothing else helps: Could any of you give me a hint about who > might be able to supply a spare crystal? I tried my directly reachable > contacts but unfortunately to no avail so far. Please consider that > similar crystals might also have found their way into other > manufacturer's constructions from that era - Sulzer, Racal, HP ... you > name it ... > > Many thanks in advance! > > Best regards ... Michael U. > _______________________________________________ > 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.

G/

Graham / KE9H

Mon, Nov 21, 2016 2:05 AM

Is your oven doing what it is supposed to be doing?

Sounds more like an oven problem than a crystal problem.

--- Graham

==

On Sun, Nov 20, 2016 at 7:00 PM, Alan Melia alan.melia@btinternet.com
wrote:

Michael a couple of wild thoughts, make sure there is no 500kHz there
(this is the crystal fundamental and the maintaining circuit should be
degenerative there. (Is it a Meecham Bridge?)

That sounds like a baseless IO GT valve (tube in US ) enclosure which was
probably originally evacuated....has the vacuum gone soft in 50 years?....I
dont know how you would check, but I think that would cause a lowering of
the frequency.

Alan
G3NYK

----- Original Message ----- From: "Michael Ulbrich" mul@rentapacs.de
To: "Time-Nuts" time-nuts@febo.com
Sent: Sunday, November 20, 2016 11:49 PM
Subject: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad?

Hi there,

I'm new to this list and have some interest in quartz crystal and
rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-)

I snatched an R&S XSD frequency standard accompanied by an XKE frequency
controller. Found the manuals on KO4BB's site (Thanks a lot for that!
BTW there's a slight mix-up of pages in that some of the XKE pages have
found their way into the XSD manual).

My initial hope of a quick and easy restoration project faded a bit when
I looked at the XSD output frequency after heating up the oven. It was
off by about -1 * 10-5 and after cranking the fine tuning for some time
and having another look at the specs I realized that the frequency was
too far off to be dialed in by the fine tuning which only covers about
+/- 2 * 10-7.

Next step was to take apart the oven and check series capacitor,
oscillator and the crystal itself. I found that even the coarse
adjustment range of the cylindrical series capacitor (40 - 110 pF) would
not allow to pull the crystal to it's specified frequency. When
replacing the series cap by a ceramic and lowering the value to just
before the oscillation breaks down (about 10 pF) I managed to set the
oscillator frequency offset to +2.5 * 10-6 at room temperature. But
even this will not suffice when taking into account that the frequency
will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up
to its operating temperature. I also checked some of the components on
the oscillator PCB which might have an influence on frequency but could
not find any fault.

The crystal itself is a disk of about 30 mm diameter mounted in a sealed
glass cylinder of about 38 mm dia. and 43 mm height. There is no socket
just 2 bare wires.. It does not show any visual signs of damage.
According to a reference given in the R&S XSD manual the crystal's
construction follows a publication from A.W. Warner "Design and
Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39,
Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that
it is an AT-cut 5th overtone design.

Now my questions:

a) Considering that this gear is about 50 years old, a "crystal gone
bad" situation shouldn't be that much of a surprise, right? But could
there be any other cause of the "huge" frequency offset besides a bad
crystal? I would very much appreciate any idea that I could try to get
this baby back on spec.

b) if nothing else helps: Could any of you give me a hint about who
might be able to supply a spare crystal? I tried my directly reachable
contacts but unfortunately to no avail so far. Please consider that
similar crystals might also have found their way into other
manufacturer's constructions from that era - Sulzer, Racal, HP ... you
name it ...

Many thanks in advance!

Best regards ... Michael U.

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

Is your oven doing what it is supposed to be doing? Sounds more like an oven problem than a crystal problem. --- Graham == On Sun, Nov 20, 2016 at 7:00 PM, Alan Melia <alan.melia@btinternet.com> wrote: > Michael a couple of wild thoughts, make sure there is no 500kHz there > (this is the crystal fundamental and the maintaining circuit should be > degenerative there. (Is it a Meecham Bridge?) > > That sounds like a baseless IO GT valve (tube in US ) enclosure which was > probably originally evacuated....has the vacuum gone soft in 50 years?....I > dont know how you would check, but I think that would cause a lowering of > the frequency. > > Alan > G3NYK > > ----- Original Message ----- From: "Michael Ulbrich" <mul@rentapacs.de> > To: "Time-Nuts" <time-nuts@febo.com> > Sent: Sunday, November 20, 2016 11:49 PM > Subject: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad? > > > > Hi there, >> >> I'm new to this list and have some interest in quartz crystal and >> rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-) >> >> I snatched an R&S XSD frequency standard accompanied by an XKE frequency >> controller. Found the manuals on KO4BB's site (Thanks a lot for that! >> BTW there's a slight mix-up of pages in that some of the XKE pages have >> found their way into the XSD manual). >> >> My initial hope of a quick and easy restoration project faded a bit when >> I looked at the XSD output frequency after heating up the oven. It was >> off by about -1 * 10-5 and after cranking the fine tuning for some time >> and having another look at the specs I realized that the frequency was >> too far off to be dialed in by the fine tuning which only covers about >> +/- 2 * 10-7. >> >> Next step was to take apart the oven and check series capacitor, >> oscillator and the crystal itself. I found that even the coarse >> adjustment range of the cylindrical series capacitor (40 - 110 pF) would >> not allow to pull the crystal to it's specified frequency. When >> replacing the series cap by a ceramic and lowering the value to just >> before the oscillation breaks down (about 10 pF) I managed to set the >> oscillator frequency offset to +2.5 * 10-6 at room temperature. But >> even this will not suffice when taking into account that the frequency >> will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up >> to its operating temperature. I also checked some of the components on >> the oscillator PCB which might have an influence on frequency but could >> not find any fault. >> >> The crystal itself is a disk of about 30 mm diameter mounted in a sealed >> glass cylinder of about 38 mm dia. and 43 mm height. There is no socket >> just 2 bare wires.. It does not show any visual signs of damage. >> According to a reference given in the R&S XSD manual the crystal's >> construction follows a publication from A.W. Warner "Design and >> Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39, >> Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that >> it is an AT-cut 5th overtone design. >> >> Now my questions: >> >> a) Considering that this gear is about 50 years old, a "crystal gone >> bad" situation shouldn't be that much of a surprise, right? But could >> there be any other cause of the "huge" frequency offset besides a bad >> crystal? I would very much appreciate any idea that I could try to get >> this baby back on spec. >> >> b) if nothing else helps: Could any of you give me a hint about who >> might be able to supply a spare crystal? I tried my directly reachable >> contacts but unfortunately to no avail so far. Please consider that >> similar crystals might also have found their way into other >> manufacturer's constructions from that era - Sulzer, Racal, HP ... you >> name it ... >> >> Many thanks in advance! >> >> Best regards ... Michael U. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/m >> ailman/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/m > ailman/listinfo/time-nuts > and follow the instructions there. >

AP

Alexander Pummer

Mon, Nov 21, 2016 3:09 AM

"that should cause lowering the frequency" and it will lower the Q of
the crystal too, therefore it will need more drive!

73

KJ6UHN

Alex

On 11/20/2016 5:00 PM, Alan Melia wrote:

Michael a couple of wild thoughts, make sure there is no 500kHz there
(this is the crystal fundamental and the maintaining circuit should be
degenerative there. (Is it a Meecham Bridge?)

That sounds like a baseless IO GT valve (tube in US ) enclosure which
was probably originally evacuated....has the vacuum gone soft in 50
years?....I dont know how you would check, but I think that would
cause a lowering of the frequency.

Alan
G3NYK

----- Original Message ----- From: "Michael Ulbrich" mul@rentapacs.de
To: "Time-Nuts" time-nuts@febo.com
Sent: Sunday, November 20, 2016 11:49 PM
Subject: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad?

Hi there,

I'm new to this list and have some interest in quartz crystal and
rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-)

I snatched an R&S XSD frequency standard accompanied by an XKE frequency
controller. Found the manuals on KO4BB's site (Thanks a lot for that!
BTW there's a slight mix-up of pages in that some of the XKE pages have
found their way into the XSD manual).

My initial hope of a quick and easy restoration project faded a bit when
I looked at the XSD output frequency after heating up the oven. It was
off by about -1 * 10-5 and after cranking the fine tuning for some time
and having another look at the specs I realized that the frequency was
too far off to be dialed in by the fine tuning which only covers about
+/- 2 * 10-7.

Next step was to take apart the oven and check series capacitor,
oscillator and the crystal itself. I found that even the coarse
adjustment range of the cylindrical series capacitor (40 - 110 pF) would
not allow to pull the crystal to it's specified frequency. When
replacing the series cap by a ceramic and lowering the value to just
before the oscillation breaks down (about 10 pF) I managed to set the
oscillator frequency offset to +2.5 * 10-6 at room temperature. But
even this will not suffice when taking into account that the frequency
will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up
to its operating temperature. I also checked some of the components on
the oscillator PCB which might have an influence on frequency but could
not find any fault.

The crystal itself is a disk of about 30 mm diameter mounted in a sealed
glass cylinder of about 38 mm dia. and 43 mm height. There is no socket
just 2 bare wires.. It does not show any visual signs of damage.
According to a reference given in the R&S XSD manual the crystal's
construction follows a publication from A.W. Warner "Design and
Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39,
Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that
it is an AT-cut 5th overtone design.

Now my questions:

a) Considering that this gear is about 50 years old, a "crystal gone
bad" situation shouldn't be that much of a surprise, right? But could
there be any other cause of the "huge" frequency offset besides a bad
crystal? I would very much appreciate any idea that I could try to get
this baby back on spec.

b) if nothing else helps: Could any of you give me a hint about who
might be able to supply a spare crystal? I tried my directly reachable
contacts but unfortunately to no avail so far. Please consider that
similar crystals might also have found their way into other
manufacturer's constructions from that era - Sulzer, Racal, HP ... you
name it ...

Many thanks in advance!

Best regards ... Michael U.

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.

No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.7859 / Virus Database: 4664/13446 - Release Date:
11/20/16

"that should cause lowering the frequency" and it will lower the Q of the crystal too, therefore it will need more drive! 73 KJ6UHN Alex On 11/20/2016 5:00 PM, Alan Melia wrote: > Michael a couple of wild thoughts, make sure there is no 500kHz there > (this is the crystal fundamental and the maintaining circuit should be > degenerative there. (Is it a Meecham Bridge?) > > That sounds like a baseless IO GT valve (tube in US ) enclosure which > was probably originally evacuated....has the vacuum gone soft in 50 > years?....I dont know how you would check, but I think that would > cause a lowering of the frequency. > > Alan > G3NYK > > ----- Original Message ----- From: "Michael Ulbrich" <mul@rentapacs.de> > To: "Time-Nuts" <time-nuts@febo.com> > Sent: Sunday, November 20, 2016 11:49 PM > Subject: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad? > > >> Hi there, >> >> I'm new to this list and have some interest in quartz crystal and >> rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-) >> >> I snatched an R&S XSD frequency standard accompanied by an XKE frequency >> controller. Found the manuals on KO4BB's site (Thanks a lot for that! >> BTW there's a slight mix-up of pages in that some of the XKE pages have >> found their way into the XSD manual). >> >> My initial hope of a quick and easy restoration project faded a bit when >> I looked at the XSD output frequency after heating up the oven. It was >> off by about -1 * 10-5 and after cranking the fine tuning for some time >> and having another look at the specs I realized that the frequency was >> too far off to be dialed in by the fine tuning which only covers about >> +/- 2 * 10-7. >> >> Next step was to take apart the oven and check series capacitor, >> oscillator and the crystal itself. I found that even the coarse >> adjustment range of the cylindrical series capacitor (40 - 110 pF) would >> not allow to pull the crystal to it's specified frequency. When >> replacing the series cap by a ceramic and lowering the value to just >> before the oscillation breaks down (about 10 pF) I managed to set the >> oscillator frequency offset to +2.5 * 10-6 at room temperature. But >> even this will not suffice when taking into account that the frequency >> will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up >> to its operating temperature. I also checked some of the components on >> the oscillator PCB which might have an influence on frequency but could >> not find any fault. >> >> The crystal itself is a disk of about 30 mm diameter mounted in a sealed >> glass cylinder of about 38 mm dia. and 43 mm height. There is no socket >> just 2 bare wires.. It does not show any visual signs of damage. >> According to a reference given in the R&S XSD manual the crystal's >> construction follows a publication from A.W. Warner "Design and >> Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39, >> Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that >> it is an AT-cut 5th overtone design. >> >> Now my questions: >> >> a) Considering that this gear is about 50 years old, a "crystal gone >> bad" situation shouldn't be that much of a surprise, right? But could >> there be any other cause of the "huge" frequency offset besides a bad >> crystal? I would very much appreciate any idea that I could try to get >> this baby back on spec. >> >> b) if nothing else helps: Could any of you give me a hint about who >> might be able to supply a spare crystal? I tried my directly reachable >> contacts but unfortunately to no avail so far. Please consider that >> similar crystals might also have found their way into other >> manufacturer's constructions from that era - Sulzer, Racal, HP ... you >> name it ... >> >> Many thanks in advance! >> >> Best regards ... Michael U. >> _______________________________________________ >> 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. > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2016.0.7859 / Virus Database: 4664/13446 - Release Date: > 11/20/16

BC

Bob Camp

Mon, Nov 21, 2016 3:21 AM

Hi

If the frequency drops as the oven warms up, you have an AT cut crystal. If
the frequency goes up as the oven warms up, you have a BT cut crystal. With an
AT or a BT, the frequency change between room and “hot” will depend a lot on
the details of the proper oven temperature. A frequency shift of 20 to 40 ppm is not
at all unusual as the oven warms up. The oscillator will only tune on frequency
once the oven is hot.

http://www.aextal.com/tutorial-frequency-stability.htm

Regardless of which cut you have (an AT is the best guess). The oven temperature
would be adjusted to put the crystal at it’s minimum sensitivity point. For an AT that
is the lowest frequency. If the oven is not heating to the correct temperature, you will
probably be unable to get the oscillator on frequency.

If there is a circuit problem, the most likely culprit are the inductors. They form tuned
traps that put the circuit onto the correct overtone. This increases the circuit’s sensitivity
to changes in inductance. 50 year old inductors may have been made with core materials
that aged more than just a little bit. I have empirical data on this :)

As others have suggested, check the oven heater along with the oscillator circuit. The
issues you see might come from either one.

Bob

On Nov 20, 2016, at 6:49 PM, Michael Ulbrich mul@rentapacs.de wrote:

Hi there,

I'm new to this list and have some interest in quartz crystal and
rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-)

I snatched an R&S XSD frequency standard accompanied by an XKE frequency
controller. Found the manuals on KO4BB's site (Thanks a lot for that!
BTW there's a slight mix-up of pages in that some of the XKE pages have
found their way into the XSD manual).

My initial hope of a quick and easy restoration project faded a bit when
I looked at the XSD output frequency after heating up the oven. It was
off by about -1 * 10-5 and after cranking the fine tuning for some time
and having another look at the specs I realized that the frequency was
too far off to be dialed in by the fine tuning which only covers about
+/- 2 * 10-7.

Next step was to take apart the oven and check series capacitor,
oscillator and the crystal itself. I found that even the coarse
adjustment range of the cylindrical series capacitor (40 - 110 pF) would
not allow to pull the crystal to it's specified frequency. When
replacing the series cap by a ceramic and lowering the value to just
before the oscillation breaks down (about 10 pF) I managed to set the
oscillator frequency offset to +2.5 * 10-6 at room temperature. But
even this will not suffice when taking into account that the frequency
will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up
to its operating temperature. I also checked some of the components on
the oscillator PCB which might have an influence on frequency but could
not find any fault.

The crystal itself is a disk of about 30 mm diameter mounted in a sealed
glass cylinder of about 38 mm dia. and 43 mm height. There is no socket
just 2 bare wires.. It does not show any visual signs of damage.
According to a reference given in the R&S XSD manual the crystal's
construction follows a publication from A.W. Warner "Design and
Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39,
Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that
it is an AT-cut 5th overtone design.

Now my questions:

a) Considering that this gear is about 50 years old, a "crystal gone
bad" situation shouldn't be that much of a surprise, right? But could
there be any other cause of the "huge" frequency offset besides a bad
crystal? I would very much appreciate any idea that I could try to get
this baby back on spec.

b) if nothing else helps: Could any of you give me a hint about who
might be able to supply a spare crystal? I tried my directly reachable
contacts but unfortunately to no avail so far. Please consider that
similar crystals might also have found their way into other
manufacturer's constructions from that era - Sulzer, Racal, HP ... you
name it ...

Many thanks in advance!

Best regards ... Michael U.

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 If the frequency drops as the oven warms up, you have an AT cut crystal. If the frequency goes up as the oven warms up, you have a BT cut crystal. With an AT or a BT, the frequency change between room and “hot” will depend a lot on the details of the proper oven temperature. A frequency shift of 20 to 40 ppm is not at all unusual as the oven warms up. The oscillator will only tune on frequency once the oven is hot. http://www.aextal.com/tutorial-frequency-stability.htm Regardless of which cut you have (an AT is the best guess). The oven temperature would be adjusted to put the crystal at it’s minimum sensitivity point. For an AT that is the lowest frequency. If the oven is not heating to the correct temperature, you will probably be unable to get the oscillator on frequency. If there is a circuit problem, the most likely culprit are the inductors. They form tuned traps that put the circuit onto the correct overtone. This increases the circuit’s sensitivity to changes in inductance. 50 year old inductors may have been made with core materials that aged more than just a little bit. I have empirical data on this :) As others have suggested, check the oven heater along with the oscillator circuit. The issues you see might come from either one. Bob > On Nov 20, 2016, at 6:49 PM, Michael Ulbrich <mul@rentapacs.de> wrote: > > Hi there, > > I'm new to this list and have some interest in quartz crystal and > rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-) > > I snatched an R&S XSD frequency standard accompanied by an XKE frequency > controller. Found the manuals on KO4BB's site (Thanks a lot for that! > BTW there's a slight mix-up of pages in that some of the XKE pages have > found their way into the XSD manual). > > My initial hope of a quick and easy restoration project faded a bit when > I looked at the XSD output frequency after heating up the oven. It was > off by about -1 * 10-5 and after cranking the fine tuning for some time > and having another look at the specs I realized that the frequency was > too far off to be dialed in by the fine tuning which only covers about > +/- 2 * 10-7. > > Next step was to take apart the oven and check series capacitor, > oscillator and the crystal itself. I found that even the coarse > adjustment range of the cylindrical series capacitor (40 - 110 pF) would > not allow to pull the crystal to it's specified frequency. When > replacing the series cap by a ceramic and lowering the value to just > before the oscillation breaks down (about 10 pF) I managed to set the > oscillator frequency offset to +2.5 * 10-6 at room temperature. But > even this will not suffice when taking into account that the frequency > will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up > to its operating temperature. I also checked some of the components on > the oscillator PCB which might have an influence on frequency but could > not find any fault. > > The crystal itself is a disk of about 30 mm diameter mounted in a sealed > glass cylinder of about 38 mm dia. and 43 mm height. There is no socket > just 2 bare wires.. It does not show any visual signs of damage. > According to a reference given in the R&S XSD manual the crystal's > construction follows a publication from A.W. Warner "Design and > Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39, > Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that > it is an AT-cut 5th overtone design. > > Now my questions: > > a) Considering that this gear is about 50 years old, a "crystal gone > bad" situation shouldn't be that much of a surprise, right? But could > there be any other cause of the "huge" frequency offset besides a bad > crystal? I would very much appreciate any idea that I could try to get > this baby back on spec. > > b) if nothing else helps: Could any of you give me a hint about who > might be able to supply a spare crystal? I tried my directly reachable > contacts but unfortunately to no avail so far. Please consider that > similar crystals might also have found their way into other > manufacturer's constructions from that era - Sulzer, Racal, HP ... you > name it ... > > Many thanks in advance! > > Best regards ... Michael U. > _______________________________________________ > 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.

AK

Attila Kinali

Mon, Nov 21, 2016 2:23 PM

Hoi Bob,

On Sun, 20 Nov 2016 22:21:29 -0500
Bob Camp kb8tq@n1k.org wrote:

50 year old inductors may have been made with core materials
that aged more than just a little bit. I have empirical data on this :)

Do you have that data available somewhere? I would be very much
interested in it.

		Attila Kinali

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

Hoi Bob, On Sun, 20 Nov 2016 22:21:29 -0500 Bob Camp <kb8tq@n1k.org> wrote: > 50 year old inductors may have been made with core materials > that aged more than just a little bit. I have empirical data on this :) Do you have that data available somewhere? I would be very much interested in it. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson

BC

Bob Camp

Mon, Nov 21, 2016 4:14 PM

Hi

On Nov 21, 2016, at 9:23 AM, Attila Kinali attila@kinali.ch wrote:

Hoi Bob,

On Sun, 20 Nov 2016 22:21:29 -0500
Bob Camp kb8tq@n1k.org wrote:

50 year old inductors may have been made with core materials
that aged more than just a little bit. I have empirical data on this :)

Do you have that data available somewhere? I would be very much
interested in it.

We had a few thousand oscillators that had to be replaced due to coil issues
in the 1970’s. We were not the only ones with the problem. Other outfits had very
similar experiences. Eventually the coil guys took a look at the materials and
“changed something”. After that the coils did not have as much aging when
run at 100C forever and ever.

Bob

		Attila Kinali

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

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 > On Nov 21, 2016, at 9:23 AM, Attila Kinali <attila@kinali.ch> wrote: > > Hoi Bob, > > On Sun, 20 Nov 2016 22:21:29 -0500 > Bob Camp <kb8tq@n1k.org> wrote: > >> 50 year old inductors may have been made with core materials >> that aged more than just a little bit. I have empirical data on this :) > > Do you have that data available somewhere? I would be very much > interested in it. > We had a few thousand oscillators that had to be replaced due to coil issues in the 1970’s. We were not the only ones with the problem. Other outfits had very similar experiences. Eventually the coil guys took a look at the materials and “changed something”. After that the coils did not have as much aging when run at 100C forever and ever. Bob > Attila Kinali > > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson > _______________________________________________ > 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.

G/

Graham / KE9H

Mon, Nov 21, 2016 5:20 PM

The core of the inductors are commonly powdered iron (of various alloys),
held together with a plastic binder.
The early plastics shrank and changed shape with time, changing the
inductance over decades.
Later binders are much more stable.
Not much you can do about it, other than change the inductors.

--- Graham

==

On Mon, Nov 21, 2016 at 10:14 AM, Bob Camp kb8tq@n1k.org wrote:

Hi

On Nov 21, 2016, at 9:23 AM, Attila Kinali attila@kinali.ch wrote:

Hoi Bob,

On Sun, 20 Nov 2016 22:21:29 -0500
Bob Camp kb8tq@n1k.org wrote:

50 year old inductors may have been made with core materials
that aged more than just a little bit. I have empirical data on this :)

Do you have that data available somewhere? I would be very much
interested in it.

We had a few thousand oscillators that had to be replaced due to coil
issues
in the 1970’s. We were not the only ones with the problem. Other outfits
had very
similar experiences. Eventually the coil guys took a look at the materials
and
“changed something”. After that the coils did not have as much aging when
run at 100C forever and ever.

Bob

                   Attila Kinali

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

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.

The core of the inductors are commonly powdered iron (of various alloys), held together with a plastic binder. The early plastics shrank and changed shape with time, changing the inductance over decades. Later binders are much more stable. Not much you can do about it, other than change the inductors. --- Graham == On Mon, Nov 21, 2016 at 10:14 AM, Bob Camp <kb8tq@n1k.org> wrote: > Hi > > > On Nov 21, 2016, at 9:23 AM, Attila Kinali <attila@kinali.ch> wrote: > > > > Hoi Bob, > > > > On Sun, 20 Nov 2016 22:21:29 -0500 > > Bob Camp <kb8tq@n1k.org> wrote: > > > >> 50 year old inductors may have been made with core materials > >> that aged more than just a little bit. I have empirical data on this :) > > > > Do you have that data available somewhere? I would be very much > > interested in it. > > > > We had a few thousand oscillators that had to be replaced due to coil > issues > in the 1970’s. We were not the only ones with the problem. Other outfits > had very > similar experiences. Eventually the coil guys took a look at the materials > and > “changed something”. After that the coils did not have as much aging when > run at 100C forever and ever. > > Bob > > > Attila Kinali > > > > -- > > It is upon moral qualities that a society is ultimately founded. All > > the prosperity and technological sophistication in the world is of no > > use without that foundation. > > -- Miss Matheson, The Diamond Age, Neil Stephenson > > _______________________________________________ > > 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. >

MU

Michael Ulbrich

Mon, Nov 21, 2016 11:31 PM

Hi all,

thanks a lot for your helpful suggestions and pointers to sources of
additional information.

I also got a few replies off list and one list member may actually have
a spare crystal!

Will report to the list as this project (hopefully) progresses.

BTW what is the "attachment policy" of this list? I will try to attach 2

small - images of the crystal (side and top view) and see if they get
through somehow.

Thanks again ... Michael

Hi all, thanks a lot for your helpful suggestions and pointers to sources of additional information. I also got a few replies off list and one list member may actually have a spare crystal! Will report to the list as this project (hopefully) progresses. BTW what is the "attachment policy" of this list? I will try to attach 2 - small - images of the crystal (side and top view) and see if they get through somehow. Thanks again ... Michael

AB

Azelio Boriani

Tue, Nov 22, 2016 12:00 AM

A comparison between AT and SC cuts' temperature stability can be found here:

http://www.conwin.com/pdfs/at_or_sc_for_ocxo.pdf

On Mon, Nov 21, 2016 at 4:21 AM, Bob Camp kb8tq@n1k.org wrote:

Hi

If the frequency drops as the oven warms up, you have an AT cut crystal. If
the frequency goes up as the oven warms up, you have a BT cut crystal. With an
AT or a BT, the frequency change between room and “hot” will depend a lot on
the details of the proper oven temperature. A frequency shift of 20 to 40 ppm is not
at all unusual as the oven warms up. The oscillator will only tune on frequency
once the oven is hot.

http://www.aextal.com/tutorial-frequency-stability.htm

Regardless of which cut you have (an AT is the best guess). The oven temperature
would be adjusted to put the crystal at it’s minimum sensitivity point. For an AT that
is the lowest frequency. If the oven is not heating to the correct temperature, you will
probably be unable to get the oscillator on frequency.

If there is a circuit problem, the most likely culprit are the inductors. They form tuned
traps that put the circuit onto the correct overtone. This increases the circuit’s sensitivity
to changes in inductance. 50 year old inductors may have been made with core materials
that aged more than just a little bit. I have empirical data on this :)

As others have suggested, check the oven heater along with the oscillator circuit. The
issues you see might come from either one.

Bob

On Nov 20, 2016, at 6:49 PM, Michael Ulbrich mul@rentapacs.de wrote:

Hi there,

I'm new to this list and have some interest in quartz crystal and
rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-)

I snatched an R&S XSD frequency standard accompanied by an XKE frequency
controller. Found the manuals on KO4BB's site (Thanks a lot for that!
BTW there's a slight mix-up of pages in that some of the XKE pages have
found their way into the XSD manual).

My initial hope of a quick and easy restoration project faded a bit when
I looked at the XSD output frequency after heating up the oven. It was
off by about -1 * 10-5 and after cranking the fine tuning for some time
and having another look at the specs I realized that the frequency was
too far off to be dialed in by the fine tuning which only covers about
+/- 2 * 10-7.

Next step was to take apart the oven and check series capacitor,
oscillator and the crystal itself. I found that even the coarse
adjustment range of the cylindrical series capacitor (40 - 110 pF) would
not allow to pull the crystal to it's specified frequency. When
replacing the series cap by a ceramic and lowering the value to just
before the oscillation breaks down (about 10 pF) I managed to set the
oscillator frequency offset to +2.5 * 10-6 at room temperature. But
even this will not suffice when taking into account that the frequency
will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up
to its operating temperature. I also checked some of the components on
the oscillator PCB which might have an influence on frequency but could
not find any fault.

The crystal itself is a disk of about 30 mm diameter mounted in a sealed
glass cylinder of about 38 mm dia. and 43 mm height. There is no socket
just 2 bare wires.. It does not show any visual signs of damage.
According to a reference given in the R&S XSD manual the crystal's
construction follows a publication from A.W. Warner "Design and
Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39,
Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that
it is an AT-cut 5th overtone design.

Now my questions:

a) Considering that this gear is about 50 years old, a "crystal gone
bad" situation shouldn't be that much of a surprise, right? But could
there be any other cause of the "huge" frequency offset besides a bad
crystal? I would very much appreciate any idea that I could try to get
this baby back on spec.

b) if nothing else helps: Could any of you give me a hint about who
might be able to supply a spare crystal? I tried my directly reachable
contacts but unfortunately to no avail so far. Please consider that
similar crystals might also have found their way into other
manufacturer's constructions from that era - Sulzer, Racal, HP ... you
name it ...

Many thanks in advance!

Best regards ... Michael U.

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.

A comparison between AT and SC cuts' temperature stability can be found here: <http://www.conwin.com/pdfs/at_or_sc_for_ocxo.pdf> On Mon, Nov 21, 2016 at 4:21 AM, Bob Camp <kb8tq@n1k.org> wrote: > Hi > > If the frequency drops as the oven warms up, you have an AT cut crystal. If > the frequency goes up as the oven warms up, you have a BT cut crystal. With an > AT or a BT, the frequency change between room and “hot” will depend a lot on > the details of the proper oven temperature. A frequency shift of 20 to 40 ppm is not > at all unusual as the oven warms up. The oscillator will only tune on frequency > once the oven is hot. > > http://www.aextal.com/tutorial-frequency-stability.htm > > Regardless of which cut you have (an AT is the best guess). The oven temperature > would be adjusted to put the crystal at it’s minimum sensitivity point. For an AT that > is the lowest frequency. If the oven is not heating to the correct temperature, you will > probably be unable to get the oscillator on frequency. > > If there is a circuit problem, the most likely culprit are the inductors. They form tuned > traps that put the circuit onto the correct overtone. This increases the circuit’s sensitivity > to changes in inductance. 50 year old inductors may have been made with core materials > that aged more than just a little bit. I have empirical data on this :) > > As others have suggested, check the oven heater along with the oscillator circuit. The > issues you see might come from either one. > > Bob > >> On Nov 20, 2016, at 6:49 PM, Michael Ulbrich <mul@rentapacs.de> wrote: >> >> Hi there, >> >> I'm new to this list and have some interest in quartz crystal and >> rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-) >> >> I snatched an R&S XSD frequency standard accompanied by an XKE frequency >> controller. Found the manuals on KO4BB's site (Thanks a lot for that! >> BTW there's a slight mix-up of pages in that some of the XKE pages have >> found their way into the XSD manual). >> >> My initial hope of a quick and easy restoration project faded a bit when >> I looked at the XSD output frequency after heating up the oven. It was >> off by about -1 * 10-5 and after cranking the fine tuning for some time >> and having another look at the specs I realized that the frequency was >> too far off to be dialed in by the fine tuning which only covers about >> +/- 2 * 10-7. >> >> Next step was to take apart the oven and check series capacitor, >> oscillator and the crystal itself. I found that even the coarse >> adjustment range of the cylindrical series capacitor (40 - 110 pF) would >> not allow to pull the crystal to it's specified frequency. When >> replacing the series cap by a ceramic and lowering the value to just >> before the oscillation breaks down (about 10 pF) I managed to set the >> oscillator frequency offset to +2.5 * 10-6 at room temperature. But >> even this will not suffice when taking into account that the frequency >> will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up >> to its operating temperature. I also checked some of the components on >> the oscillator PCB which might have an influence on frequency but could >> not find any fault. >> >> The crystal itself is a disk of about 30 mm diameter mounted in a sealed >> glass cylinder of about 38 mm dia. and 43 mm height. There is no socket >> just 2 bare wires.. It does not show any visual signs of damage. >> According to a reference given in the R&S XSD manual the crystal's >> construction follows a publication from A.W. Warner "Design and >> Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39, >> Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that >> it is an AT-cut 5th overtone design. >> >> Now my questions: >> >> a) Considering that this gear is about 50 years old, a "crystal gone >> bad" situation shouldn't be that much of a surprise, right? But could >> there be any other cause of the "huge" frequency offset besides a bad >> crystal? I would very much appreciate any idea that I could try to get >> this baby back on spec. >> >> b) if nothing else helps: Could any of you give me a hint about who >> might be able to supply a spare crystal? I tried my directly reachable >> contacts but unfortunately to no avail so far. Please consider that >> similar crystals might also have found their way into other >> manufacturer's constructions from that era - Sulzer, Racal, HP ... you >> name it ... >> >> Many thanks in advance! >> >> Best regards ... Michael U. >> _______________________________________________ >> 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@lists.febo.com

Rohde & Schwarz XSD 2.5 MHz crystal gone bad?