Are there SC-crystals out there in the wild that are not Overtone?
I had a Morion MV89A that would stop oscillating when Vtune was more
than +600 mV.
So I cut it open to recover at least the crystal, for own experiments.
Pics are there:
<
https://www.flickr.com/photos/137684711@N07/49585174873/in/album-72157662535945536/
>
and then following the right arrow.
To get a first impression, I soldered the crystal to an SMA plug and put
it on an
R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz resonance
as a 15 dB dip. There was also a resonance at 5.45 and a smaller one
another 90 KHz
higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1.6666 MHz, so it should be a
fundamental crystal?
Is that common?
I made most measurements at room temperature. I can turn the hot air solder
station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz
resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1 Hz
bandwidth
is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones stronger
with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll make
a board
for the PI fixture as described by Bernd Neubig in his crystal cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that
does not mean
that the ZVB needs service.
cheers, Gerhard
Hi
There certainly are fundamental SC’s out there.
SC’s typically have motional resistances above 50 ohms. This usually makes transmission
a better way to look for this or that resonance than impedance.
Bob
On Feb 25, 2020, at 7:42 PM, Gerhard Hoffmann via time-nuts time-nuts@lists.febo.com wrote:
I had a Morion MV89A that would stop oscillating when Vtune was more than +600 mV.
So I cut it open to recover at least the crystal, for own experiments.
Pics are there:
< https://www.flickr.com/photos/137684711@N07/49585174873/in/album-72157662535945536/ >
and then following the right arrow.
To get a first impression, I soldered the crystal to an SMA plug and put it on an
R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz resonance
as a 15 dB dip. There was also a resonance at 5.45 and a smaller one another 90 KHz
higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1.6666 MHz, so it should be a fundamental crystal?
Is that common?
I made most measurements at room temperature. I can turn the hot air solder
station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1 Hz bandwidth
is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones stronger with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll make a board
for the PI fixture as described by Bernd Neubig in his crystal cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that does not mean
that the ZVB needs service.
cheers, Gerhard
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Hoi Gerhard!
On Wed, 26 Feb 2020 01:42:11 +0100
Gerhard Hoffmann via time-nuts time-nuts@lists.febo.com wrote:
Pics are there:
<
https://www.flickr.com/photos/137684711@N07/49585174873/in/album-72157662535945536/
>
Nice pictures! Thanks!
Do you know what the two coils/transformers that were glued to the
outside of the inner oven were for?
But I could not see anything at 1 or 1.6666 MHz, so it should be a
fundamental crystal?
Judging from the specs, very unlikely. The short-term and long-term
stability are consistent with what I expect of an 3rd overtone 5MHz
SC cut crystal. The lower Q of a fundamental mode crystal would result
in a higher close in phase noise and the thinner plate would lead to
a higher aging rate at tau of one day. I can see two reasons for you
to not see the fundamental mode: Either your measurement setup was not
done properly to measure quartz crystals (see Bob's comment on impedance)
or they manufactured the crystal for low fundamental mode.
Bernd Neubig has written a few documents on how to measure crystals
properly, which should be available from Axtal's website, if I'm not
mistaken.
Attila Kinali
--
In science if you know what you are doing you should not be doing it.
In engineering if you do not know what you are doing you should not be doing it.
-- Richard W. Hamming, The Art of Doing Science and Engineering
Am 26.02.20 um 15:22 schrieb Attila Kinali via time-nuts:
Do you know what the two coils/transformers that were glued to the
outside of the inner oven were for?
I guess they are part of the 5 -> 10 MHz doubler
Bernd Neubig has written a few documents on how to measure crystals
properly, which should be available from Axtal's website, if I'm not
mistaken.
Yes, I mentionend the Quarzkochbuch above. There was a nonstandard
solution proposed by Detleff Burchard in UKW-Berichte / VHF Communications
4/92 but I can't find my copy. I had built the head some 20 years ago
and it seemed to work. The drawback was that one had to compensate C0,
at least at 100 MHz.
regards, Gerhard
Hi Gerhard,
I am rather sure that it is a 5 MHz 3rd overtone crystal.
the resistance should be in the 80 to 110 Ohm range and Q about 1.5 million. You can see the resonance without ringing in a span of 100 Hz or smaller with a sweep time of 10 sec minimum.
See attached the response of a 5 MHz SC3 crystal in HC-40/U package.
Indeed the 5.45 MHz is the B-mode which has a temperature coefficient of -30 ppm/K
Because the crystal blank has a plano-convex shape. The overtones are quite far away from 3 times or 5 times the fundamental mode. 3rd overtone is about (rough guess) 2.9 time of fundamental mode.
To find them you must really carefully sweep around a few 10 to 100 kHz span with slow sweep time a narrow bandwidth
Regards
Bernd
DK1AG
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag von Gerhard Hoffmann via time-nuts
Gesendet: Mittwoch, 26. Februar 2020 01:42
To get a first impression, I soldered the crystal to an SMA plug and put it on an
R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz resonance
as a 15 dB dip. There was also a resonance at 5.45 and a smaller one another 90 KHz
higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1.6666 MHz, so it should be a fundamental crystal?
Is that common?
I made most measurements at room temperature. I can turn the hot air solder
station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1 Hz bandwidth
is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones stronger with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll make a board
for the PI fixture as described by Bernd Neubig in his crystal cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that does not mean
that the ZVB needs service.
time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Hi
Ok, so just to run the math:
5 MHz / 2.9 = 1.724 MHz
If the Q at the fundamental is 500K (a wild guess) then 1.724 MHz / 500,000 = 3.4 Hz
In a world where a synthesized sweeper might be stepping in 10Hz steps, that’s an
easy one to miss.
Bob
On Feb 26, 2020, at 11:40 PM, Bernd Neubig BNeubig@t-online.de wrote:
Hi Gerhard,
I am rather sure that it is a 5 MHz 3rd overtone crystal.
the resistance should be in the 80 to 110 Ohm range and Q about 1.5 million. You can see the resonance without ringing in a span of 100 Hz or smaller with a sweep time of 10 sec minimum.
See attached the response of a 5 MHz SC3 crystal in HC-40/U package.
Indeed the 5.45 MHz is the B-mode which has a temperature coefficient of -30 ppm/K
Because the crystal blank has a plano-convex shape. The overtones are quite far away from 3 times or 5 times the fundamental mode. 3rd overtone is about (rough guess) 2.9 time of fundamental mode.
To find them you must really carefully sweep around a few 10 to 100 kHz span with slow sweep time a narrow bandwidth
Regards
Bernd
DK1AG
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag von Gerhard Hoffmann via time-nuts
Gesendet: Mittwoch, 26. Februar 2020 01:42
To get a first impression, I soldered the crystal to an SMA plug and put it on an
R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz resonance
as a 15 dB dip. There was also a resonance at 5.45 and a smaller one another 90 KHz
higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1.6666 MHz, so it should be a fundamental crystal?
Is that common?
I made most measurements at room temperature. I can turn the hot air solder
station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1 Hz bandwidth
is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones stronger with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll make a board
for the PI fixture as described by Bernd Neubig in his crystal cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that does not mean
that the ZVB needs service.
time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
<5MC5735H.jpg>_______________________________________________
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and follow the instructions there.
Hi,
Even if my VNA steps in 1 Hz if I ask it kindly, it can be a bit
teadious work to find it.
Cheers,
Magnus
On 2020-02-27 14:35, Bob kb8tq wrote:
Hi
Ok, so just to run the math:
5 MHz / 2.9 = 1.724 MHz
If the Q at the fundamental is 500K (a wild guess) then 1.724 MHz / 500,000 = 3.4 Hz
In a world where a synthesized sweeper might be stepping in 10Hz steps, that’s an
easy one to miss.
Bob
On Feb 26, 2020, at 11:40 PM, Bernd Neubig BNeubig@t-online.de wrote:
Hi Gerhard,
I am rather sure that it is a 5 MHz 3rd overtone crystal.
the resistance should be in the 80 to 110 Ohm range and Q about 1.5 million. You can see the resonance without ringing in a span of 100 Hz or smaller with a sweep time of 10 sec minimum.
See attached the response of a 5 MHz SC3 crystal in HC-40/U package.
Indeed the 5.45 MHz is the B-mode which has a temperature coefficient of -30 ppm/K
Because the crystal blank has a plano-convex shape. The overtones are quite far away from 3 times or 5 times the fundamental mode. 3rd overtone is about (rough guess) 2.9 time of fundamental mode.
To find them you must really carefully sweep around a few 10 to 100 kHz span with slow sweep time a narrow bandwidth
Regards
Bernd
DK1AG
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag von Gerhard Hoffmann via time-nuts
Gesendet: Mittwoch, 26. Februar 2020 01:42
To get a first impression, I soldered the crystal to an SMA plug and put it on an
R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz resonance
as a 15 dB dip. There was also a resonance at 5.45 and a smaller one another 90 KHz
higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1.6666 MHz, so it should be a fundamental crystal?
Is that common?
I made most measurements at room temperature. I can turn the hot air solder
station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1 Hz bandwidth
is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones stronger with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll make a board
for the PI fixture as described by Bernd Neubig in his crystal cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that does not mean
that the ZVB needs service.
time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
<5MC5735H.jpg>_______________________________________________
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and follow the instructions there.
If you start off viewing the crystal in series (S21) I believe that you'll
be able to see
some response far enough away from the resonance to make it easier to find.
Dana
On Thu, Feb 27, 2020 at 9:39 AM Magnus Danielson magnus@rubidium.se wrote:
Hi,
Even if my VNA steps in 1 Hz if I ask it kindly, it can be a bit
teadious work to find it.
Cheers,
Magnus
On 2020-02-27 14:35, Bob kb8tq wrote:
Hi
Ok, so just to run the math:
5 MHz / 2.9 = 1.724 MHz
If the Q at the fundamental is 500K (a wild guess) then 1.724 MHz /
500,000 = 3.4 Hz
In a world where a synthesized sweeper might be stepping in 10Hz
steps, that’s an
easy one to miss.
Bob
On Feb 26, 2020, at 11:40 PM, Bernd Neubig BNeubig@t-online.de wrote:
Hi Gerhard,
I am rather sure that it is a 5 MHz 3rd overtone crystal.
the resistance should be in the 80 to 110 Ohm range and Q about 1.5
million. You can see the resonance without ringing in a span of 100 Hz or
smaller with a sweep time of 10 sec minimum.
See attached the response of a 5 MHz SC3 crystal in HC-40/U package.
Indeed the 5.45 MHz is the B-mode which has a temperature coefficient
of -30 ppm/K
Because the crystal blank has a plano-convex shape. The overtones are
quite far away from 3 times or 5 times the fundamental mode. 3rd overtone
is about (rough guess) 2.9 time of fundamental mode.
To find them you must really carefully sweep around a few 10 to 100 kHz
span with slow sweep time a narrow bandwidth
Regards
Bernd
DK1AG
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag
von Gerhard Hoffmann via time-nuts
Gesendet: Mittwoch, 26. Februar 2020 01:42
To get a first impression, I soldered the crystal to an SMA plug and
put it on an
R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz
resonance
as a 15 dB dip. There was also a resonance at 5.45 and a smaller one
another 90 KHz
higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1.6666 MHz, so it should be a
fundamental crystal?
Is that common?
I made most measurements at room temperature. I can turn the hot air
solder
station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz
resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1 Hz
bandwidth
is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones stronger
with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll make
a board
for the PI fixture as described by Bernd Neubig in his crystal cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that
does not mean
and follow the instructions there.
<5MC5735H.jpg>_______________________________________________
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To unsubscribe, go to
and follow the instructions there.
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and follow the instructions there.
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and follow the instructions there.
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Rick N6RK
On 2/27/2020 5:35 AM, Bob kb8tq wrote:
Hi
Ok, so just to run the math:
5 MHz / 2.9 = 1.724 MHz
If the Q at the fundamental is 500K (a wild guess) then 1.724 MHz / 500,000 = 3.4 Hz
In a world where a synthesized sweeper might be stepping in 10Hz steps, that’s an
easy one to miss.
Bob
On Feb 26, 2020, at 11:40 PM, Bernd Neubig BNeubig@t-online.de wrote:
Hi Gerhard,
I am rather sure that it is a 5 MHz 3rd overtone crystal.
the resistance should be in the 80 to 110 Ohm range and Q about 1.5 million. You can see the resonance without ringing in a span of 100 Hz or smaller with a sweep time of 10 sec minimum.
See attached the response of a 5 MHz SC3 crystal in HC-40/U package.
Indeed the 5.45 MHz is the B-mode which has a temperature coefficient of -30 ppm/K
Because the crystal blank has a plano-convex shape. The overtones are quite far away from 3 times or 5 times the fundamental mode. 3rd overtone is about (rough guess) 2.9 time of fundamental mode.
To find them you must really carefully sweep around a few 10 to 100 kHz span with slow sweep time a narrow bandwidth
Regards
Bernd
DK1AG
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag von Gerhard Hoffmann via time-nuts
Gesendet: Mittwoch, 26. Februar 2020 01:42
To get a first impression, I soldered the crystal to an SMA plug and put it on an
R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz resonance
as a 15 dB dip. There was also a resonance at 5.45 and a smaller one another 90 KHz
higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1.6666 MHz, so it should be a fundamental crystal?
Is that common?
I made most measurements at room temperature. I can turn the hot air solder
station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1 Hz bandwidth
is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones stronger with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll make a board
for the PI fixture as described by Bernd Neubig in his crystal cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that does not mean
that the ZVB needs service.
time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
<5MC5735H.jpg>_______________________________________________
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and follow the instructions there.
On 2/27/20 10:45, Richard (Rick) Karlquist wrote:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
I was going to suggest pumping it with white noise and then doing a long
FFT to see which bin has any energy in it to get into the ballpark but
building an oscillator seems to be far and away the simplest solution.
Rick N6RK
On 2/27/2020 5:35 AM, Bob kb8tq wrote:
Hi
Ok, so just to run the math:
5 MHz / 2.9 = 1.724 MHz
If the Q at the fundamental is 500K (a wild guess) then 1.724 MHz /
500,000 = 3.4 Hz
In a world where a synthesized sweeper might be stepping in 10Hz
steps, that’s an
easy one to miss.
Bob
On Feb 26, 2020, at 11:40 PM, Bernd Neubig BNeubig@t-online.de wrote:
Hi Gerhard,
I am rather sure that it is a 5 MHz 3rd overtone crystal.
the resistance should be in the 80 to 110 Ohm range and Q about 1.5
million. You can see the resonance without ringing in a span of 100
Hz or smaller with a sweep time of 10 sec minimum.
See attached the response of a 5 MHz SC3 crystal in HC-40/U package.
Indeed the 5.45 MHz is the B-mode which has a temperature
coefficient of -30 ppm/K
Because the crystal blank has a plano-convex shape. The overtones
are quite far away from 3 times or 5 times the fundamental mode. 3rd
overtone is about (rough guess) 2.9 time of fundamental mode.
To find them you must really carefully sweep around a few 10 to 100
kHz span with slow sweep time a narrow bandwidth
Regards
Bernd
DK1AG
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag
von Gerhard Hoffmann via time-nuts
Gesendet: Mittwoch, 26. Februar 2020 01:42
To get a first impression, I soldered the crystal to an SMA plug and
put it on an
R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz
resonance
as a 15 dB dip. There was also a resonance at 5.45 and a smaller
one another 90 KHz
higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1.6666 MHz, so it should be a
fundamental crystal?
Is that common?
I made most measurements at room temperature. I can turn the hot air
solder
station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz
resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1
Hz bandwidth
is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones
stronger with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll
make a board
for the PI fixture as described by Bernd Neubig in his crystal
cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that
does not mean
that the ZVB needs service.
time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe,
go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
<5MC5735H.jpg>_______________________________________________
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To unsubscribe, go to
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time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to
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and follow the instructions there.
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and follow the instructions there.
--
Brian Lloyd
706 Flightline
Spring Branch, TX 78070
brian@lloyd.aero mailto://brian@lloyd.aero
+1.210.802.8359
Am 27.02.20 um 17:45 schrieb Richard (Rick) Karlquist:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
5.000 MHz. That was easy. It used to be in something Colpitts-like
for 30 years, but did not age to its advantage like good Scotch.
I was just puzzled because I could not find the fundamental.
When the subharmonic is so far off as Bernd has said, then I could
well have searched a day with the network analyzer at 1 Hz receiver
bandwidth without finding it. I'll postpone that to the weekend.
Someone has reverse-engineered the whole oscillator:
< https://www.bartelsos.de/dk7jb.php/ocxo-morion-mv89a?download=118 >
Jörn seems to read the timenut list, HI!
cheers, Gerhard
(now I'll have to shovel some snow, first time for this winter!)
Rick N6RK
On 2/27/2020 5:35 AM, Bob kb8tq wrote:
Hi
Ok, so just to run the math:
5 MHz / 2.9 = 1.724 MHz
If the Q at the fundamental is 500K (a wild guess) then 1.724 MHz /
500,000 = 3.4 Hz
In a world where a synthesized sweeper might be stepping in 10Hz
steps, that’s an
easy one to miss.
Bob
On Feb 26, 2020, at 11:40 PM, Bernd Neubig BNeubig@t-online.de wrote:
Hi Gerhard,
I am rather sure that it is a 5 MHz 3rd overtone crystal.
the resistance should be in the 80 to 110 Ohm range and Q about 1.5
million. You can see the resonance without ringing in a span of 100
Hz or smaller with a sweep time of 10 sec minimum.
See attached the response of a 5 MHz SC3 crystal in HC-40/U package.
Indeed the 5.45 MHz is the B-mode which has a temperature
coefficient of -30 ppm/K
Because the crystal blank has a plano-convex shape. The overtones
are quite far away from 3 times or 5 times the fundamental mode. 3rd
overtone is about (rough guess) 2.9 time of fundamental mode.
To find them you must really carefully sweep around a few 10 to 100
kHz span with slow sweep time a narrow bandwidth
Regards
Bernd
DK1AG
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag
von Gerhard Hoffmann via time-nuts
Gesendet: Mittwoch, 26. Februar 2020 01:42
To get a first impression, I soldered the crystal to an SMA plug and
put it on an
R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz
resonance
as a 15 dB dip. There was also a resonance at 5.45 and a smaller
one another 90 KHz
higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1.6666 MHz, so it should be a
fundamental crystal?
Is that common?
I made most measurements at room temperature. I can turn the hot air
solder
station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz
resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1
Hz bandwidth
is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones
stronger with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll
make a board
for the PI fixture as described by Bernd Neubig in his crystal
cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that
does not mean
that the ZVB needs service.
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On 2/27/20 8:45 AM, Richard (Rick) Karlquist wrote:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Rick N6RK
But does a deForest Audion (ref Colpitts patent 1624537 1918) have
enough gain at 5 or 10 MHz?
I guess so, by 1930 deForest was selling oscillators and receivers at
15,000 kilocycles. Although I didn't see any indication of crystal
oscillators - they're all LC tuned. (One mention of crystal control is
in an article about a SW crystal controlled Transmitter by Lester
Spangenberg)
https://www.americanradiohistory.com/Archive-Radio-News/30s/Radio-News-1930-05-R.pdf
(Timenuts - your experience and training probably qualifies you for a
job in Radio-Television - Talking Pictures, see the ads!)
I seem to recall that crystals for frequency control (on a commercial
basis) were sort of a post WW2 thing (partly because of developments in
piezo hydrophones for sonar)
I seem to recall that crystals for frequency control (on a commercial
basis) were sort of a post WW2 thing (partly because of developments in
piezo hydrophones for sonar)
Crystals for radios were well established pre-WWII. There was an
FCS paper ~30 years ago about the WWII quartz shortage and the
research to find alternatives to quartz (which they didn't know
how to grow synthetically yet). Spoiler alert: there is nothing
else like quartz!.
Novice hams routinely used war surplus crystals (FT-243?) after the war.
I had some at 3.7 and 7.15 MHz fundamental and they oscillated
fine with receiving tubes, circa 1965.
There was some standard military crystal test set from the war that
was always referenced in crystal specs in those days. The test
set was in essence a "golden" oscillator.
Rick N6RK
I remember opening up those military crystals and sanding them down with Ajax cleaner to raise the frequency or rubbing a little solder on the plate to lower it for CW transmitters.
High school days. 😊
--
David VanHorn
Lead Hardware Engineer
Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: 303-417-1345 x110
email: david.vanhorn@backcountryaccess.com
Hi
The crystal industry in the US went from a couple of outfits (mostly in PA) making <
a hundred a month in the 1930’s, to a massive bunch of outfits during WWII. Most
were turning out a couple hundred an hour.
Much of that collapsed when the war ended and the demand went away. A few outfits
combined with others. The vast majority of companies simply vanished.
Bob
On Feb 27, 2020, at 2:07 PM, jimlux jimlux@earthlink.net wrote:
On 2/27/20 8:45 AM, Richard (Rick) Karlquist wrote:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Rick N6RK
But does a deForest Audion (ref Colpitts patent 1624537 1918) have enough gain at 5 or 10 MHz?
I guess so, by 1930 deForest was selling oscillators and receivers at 15,000 kilocycles. Although I didn't see any indication of crystal oscillators - they're all LC tuned. (One mention of crystal control is in an article about a SW crystal controlled Transmitter by Lester Spangenberg)
https://www.americanradiohistory.com/Archive-Radio-News/30s/Radio-News-1930-05-R.pdf
(Timenuts - your experience and training probably qualifies you for a job in Radio-Television - Talking Pictures, see the ads!)
I seem to recall that crystals for frequency control (on a commercial basis) were sort of a post WW2 thing (partly because of developments in piezo hydrophones for sonar)
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Been there; done that!
Rick N6RK
On 2/27/2020 12:15 PM, David Van Horn via time-nuts wrote:
I remember opening up those military crystals and sanding them down with Ajax cleaner to raise the frequency or rubbing a little solder on the plate to lower it for CW transmitters.
High school days. 😊
--
David VanHorn
Lead Hardware Engineer
Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: 303-417-1345 x110
email: david.vanhorn@backcountryaccess.com
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Hi
Ahhhh, but did you then whip up a batch of ammonium bifluoride to clean them up after
playing with the grinding compound? :) They figured that part out part way through WWII.
The lack proper post grind etch just about had all the radios out there out of service.
Bob
On Feb 27, 2020, at 5:12 PM, Richard (Rick) Karlquist richard@karlquist.com wrote:
Been there; done that!
Rick N6RK
On 2/27/2020 12:15 PM, David Van Horn via time-nuts wrote:
I remember opening up those military crystals and sanding them down with Ajax cleaner to raise the frequency or rubbing a little solder on the plate to lower it for CW transmitters.
High school days. 😊
David VanHorn
Lead Hardware Engineer
Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: 303-417-1345 x110
email: david.vanhorn@backcountryaccess.com
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On Thu, 27 Feb 2020 08:45:16 -0800
"Richard (Rick) Karlquist" richard@karlquist.com wrote:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Yes, but how many of us can build a time-nuts quality oscillator?
I'm still lacking that paper/book that teaches me how to build
a high stability oscillator.
I have a couple of 5MHz 3rd OT SC cut crystals in HC-37 case sitting
in a box, waiting to be used as some oscillator, I just lack the knowledge
to make good use of them.
Attila Kinali
--
In science if you know what you are doing you should not be doing it.
In engineering if you do not know what you are doing you should not be doing it.
-- Richard W. Hamming, The Art of Doing Science and Engineering
That's not relevant.
The idea is to see what frequency the crystal oscillates at not to build a high stability oscillator.
If can be made to oscillate at a frequency somewhere around 5MHz/3 then its likely a third overtone crystal.
Bruce
On 28 February 2020 at 23:34 Attila Kinali attila@kinali.ch wrote:
On Thu, 27 Feb 2020 08:45:16 -0800
"Richard (Rick) Karlquist" richard@karlquist.com wrote:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Yes, but how many of us can build a time-nuts quality oscillator?
I'm still lacking that paper/book that teaches me how to build
a high stability oscillator.
I have a couple of 5MHz 3rd OT SC cut crystals in HC-37 case sitting
in a box, waiting to be used as some oscillator, I just lack the knowledge
to make good use of them.
Attila Kinali
--
In science if you know what you are doing you should not be doing it.
In engineering if you do not know what you are doing you should not be doing it.
-- Richard W. Hamming, The Art of Doing Science and Engineering
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Well said, been looking for this « tutorial» eagerly myself too.
GC.
Le 28 févr. 2020 à 11:35, Attila Kinali attila@kinali.ch a écrit :
On Thu, 27 Feb 2020 08:45:16 -0800
"Richard (Rick) Karlquist" richard@karlquist.com wrote:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Yes, but how many of us can build a time-nuts quality oscillator?
I'm still lacking that paper/book that teaches me how to build
a high stability oscillator.
I have a couple of 5MHz 3rd OT SC cut crystals in HC-37 case sitting
in a box, waiting to be used as some oscillator, I just lack the knowledge
to make good use of them.
Attila Kinali
--
In science if you know what you are doing you should not be doing it.
In engineering if you do not know what you are doing you should not be doing it.
-- Richard W. Hamming, The Art of Doing Science and Engineering
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Reference on high quality crystal oscillators:
https://www.bartelsos.de/dk7jb.php/colpitts-oszillator-rohde
On Fri, Feb 28, 2020 at 11:35 AM Attila Kinali attila@kinali.ch wrote:
On Thu, 27 Feb 2020 08:45:16 -0800
"Richard (Rick) Karlquist" richard@karlquist.com wrote:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Yes, but how many of us can build a time-nuts quality oscillator?
I'm still lacking that paper/book that teaches me how to build
a high stability oscillator.
I have a couple of 5MHz 3rd OT SC cut crystals in HC-37 case sitting
in a box, waiting to be used as some oscillator, I just lack the knowledge
to make good use of them.
Attila Kinali
--
In science if you know what you are doing you should not be doing it.
In engineering if you do not know what you are doing you should not be doing it.
-- Richard W. Hamming, The Art of Doing Science and Engineering
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On 2/28/20 2:34 AM, Attila Kinali wrote:
On Thu, 27 Feb 2020 08:45:16 -0800
"Richard (Rick) Karlquist" richard@karlquist.com wrote:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Yes, but how many of us can build a time-nuts quality oscillator?
I'm still lacking that paper/book that teaches me how to build
a high stability oscillator.
I think to a large extent that is more art than science. High
performance electronics (low noise, high stability, mass production, you
name it) is always a combination of tradeoffs of non-ideal behavior,
much of which is not necessarily modelable in a systems sense. So the
trades get made by "gut feel" developed from experience.
Driving along that path a bit further, the really fundamental
improvements come when someone figures out how to get better performance
without needing art and skill. Movable type brought the written word to
everyone. Offset printing brought high quality image reproduction to the
masses. Silicon lithography brought computation to all of us.
I have a couple of 5MHz 3rd OT SC cut crystals in HC-37 case sitting
in a box, waiting to be used as some oscillator, I just lack the knowledge
to make good use of them.
Experiment. Build a fet or MMIC oscillator and see how it works.
Attila Kinali
Hi
On Feb 28, 2020, at 9:33 AM, jimlux jimlux@earthlink.net wrote:
On 2/28/20 2:34 AM, Attila Kinali wrote:
On Thu, 27 Feb 2020 08:45:16 -0800
"Richard (Rick) Karlquist" richard@karlquist.com wrote:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Yes, but how many of us can build a time-nuts quality oscillator?
I'm still lacking that paper/book that teaches me how to build
a high stability oscillator.
I think to a large extent that is more art than science. High performance electronics (low noise, high stability, mass production, you name it) is always a combination of tradeoffs of non-ideal behavior, much of which is not necessarily modelable in a systems sense. So the trades get made by "gut feel" developed from experience.
There are papers that dive into some of the tradeoffs. Things like
phase noise get a lot of attention. However, every attempt that I’m
aware of to write an “oscillator cookbook” has either become very
narrow ( = how to use this chip in a clock oscillator) or has hit a wall
before becoming useful.
The normal way high precision oscillators are “learned" is to either
learn it from the guy on the next bench (who already knows) or to
do a whole lot of experimentation. Even there, the process is pretty
narrowly focused.
Bob
Driving along that path a bit further, the really fundamental improvements come when someone figures out how to get better performance without needing art and skill. Movable type brought the written word to everyone. Offset printing brought high quality image reproduction to the masses. Silicon lithography brought computation to all of us.
I have a couple of 5MHz 3rd OT SC cut crystals in HC-37 case sitting
in a box, waiting to be used as some oscillator, I just lack the knowledge
to make good use of them.
Experiment. Build a fet or MMIC oscillator and see how it works.
Attila Kinali
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Am 28.02.20 um 11:34 schrieb Attila Kinali:
Yes, but how many of us can build a time-nuts quality oscillator?
I'm still lacking that paper/book that teaches me how to build
a high stability oscillator.
Especially if you see THIS in a tutorial and 5 cm below the OOOH
so precise phase noise simulation results of this circuit:
----- < short.png > -----
That builds confidence.
But Bernd was very precise with his prediction where the fundamental
of the SC crystal was to be expected. The sweep took abt. 25 minutes @
1Hz RBW.
The step on the left side is where the next measurement happens.
The crystal laid openly on the end of the port cable on the table at
room temperature.
--- < fundamental.png > ---
I have a couple of 5MHz 3rd OT SC cut crystals in HC-37 case sitting
in a box, waiting to be used as some oscillator, I just lack the knowledge
to make good use of them.
regards, Gerhard
Many crystals possess spurious modes not terribly far from the desired Hi-Q
mode.
Since the spurious mode(s) are lower Q, oscillation on one of these can
build up
faster than oscillation in the desired mode, driving the sustaining
amplifier into
compression before the desired oscillating mode really gets going. This
will leave
only the fastest-growing mode as the winner. This is not speculation- I've
seen
it happen.
My point is that just building an oscillator with an unknown crystal has no
assurance
of running where you really want it to, thus leading you astray.
Discovering all these
modes is a big part of the benefit of studying the crystal with a VNA or
similar instrument
before building anything. Forewarned is forearmed- you then have a better
chance of
building an oscillator that does what you want it to do.
Dana
On Thu, Feb 27, 2020 at 10:46 AM Richard (Rick) Karlquist <
richard@karlquist.com> wrote:
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Rick N6RK
On 2/27/2020 5:35 AM, Bob kb8tq wrote:
Hi
Ok, so just to run the math:
5 MHz / 2.9 = 1.724 MHz
If the Q at the fundamental is 500K (a wild guess) then 1.724 MHz /
500,000 = 3.4 Hz
In a world where a synthesized sweeper might be stepping in 10Hz
steps, that’s an
easy one to miss.
Bob
On Feb 26, 2020, at 11:40 PM, Bernd Neubig BNeubig@t-online.de wrote:
Hi Gerhard,
I am rather sure that it is a 5 MHz 3rd overtone crystal.
the resistance should be in the 80 to 110 Ohm range and Q about 1.5
million. You can see the resonance without ringing in a span of 100 Hz or
smaller with a sweep time of 10 sec minimum.
See attached the response of a 5 MHz SC3 crystal in HC-40/U package.
Indeed the 5.45 MHz is the B-mode which has a temperature coefficient
of -30 ppm/K
Because the crystal blank has a plano-convex shape. The overtones are
quite far away from 3 times or 5 times the fundamental mode. 3rd overtone
is about (rough guess) 2.9 time of fundamental mode.
To find them you must really carefully sweep around a few 10 to 100 kHz
span with slow sweep time a narrow bandwidth
Regards
Bernd
DK1AG
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag
von Gerhard Hoffmann via time-nuts
Gesendet: Mittwoch, 26. Februar 2020 01:42
To get a first impression, I soldered the crystal to an SMA plug and
put it on an
R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz
resonance
as a 15 dB dip. There was also a resonance at 5.45 and a smaller one
another 90 KHz
higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1.6666 MHz, so it should be a
fundamental crystal?
Is that common?
I made most measurements at room temperature. I can turn the hot air
solder
station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz
resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1 Hz
bandwidth
is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones stronger
with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll make
a board
for the PI fixture as described by Bernd Neubig in his crystal cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that
does not mean
and follow the instructions there.
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Basically you are right. One of the problem is, that SC-cut crystals possess
a strong "B-mode" resonance just 9% above the desired stable "C-mode". The
B-mode has a similar or even a bit lower resistance than the C-mode, and has
a temperature coefficient of -30 ppm/K. It is a temperature sensing mode,
and sometimes used for that purpose.
The existence of two close modes with similar resistance makes SC-cut
oscillator design a bit of an art, but not magic.
Bernd
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag von
Bruce Griffiths
Gesendet: Freitag, 28. Februar 2020 12:08
The idea is to see what frequency the crystal oscillates at not to build a
high stability oscillator.
If can be made to oscillate at a frequency somewhere around 5MHz/3 then its
likely a third overtone crystal.
I am glad you could confirm my rough estimate.
The critical point when measuring SC-cut crystals at room temperature is, that their f(T) response is rather steep at room temperature. There even minor temperature variations during the sweep (or between two sweeps) will cause a shift of the impedance response.
This is the reason for the small edge at the left side of Gerhard's picture.
Best regards
Bernd
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag von Gerhard Hoffmann
Gesendet: Freitag, 28. Februar 2020 16:44
An: time-nuts@lists.febo.com
Betreff: Re: [time-nuts] Are there SC-crystals out there in the wild that are not Overtone?
...
But Bernd was very precise with his prediction where the fundamental
of the SC crystal was to be expected. The sweep took abt. 25 minutes @ 1Hz RBW.
The step on the left side is where the next measurement happens.
The crystal laid openly on the end of the port cable on the table at
room temperature.
--- < fundamental.png > ---
You are right. As I am usually stating in my crystal seminars: "You are ordering a crystal with one particular frequency, but the manufacturer supplies with the crystals free of charge a bunch of additional frequencies, which are not mentioned on the marking."
There is a multitude of spurious in real crystals:
- So-called an-harmonic spurious resonances, which are all above the desired frequency. For plano-convex crystals, as the usual high-precision overtone crystals at 5 MHz or 10 MHz, there are two or three (at least) very strong spuriii about 100 kHz ~ 200 kHz above. In poorly designed crystals these modes could be as strong or even stronger than the main mode.
- The other overtones including the fundamental mode with their an-harmonics are also always present. Higher overtones usually have higher resistance than the main mode, but the fundamental mode of a 3rd overtone could have a lower resistance than the desired 3rd OT. The B-Mode is a temperature sensor mode with -30 ppm/K f(T) slope
- SC-cut crystals have a strong "B-mode only 9% above the main mode, which has comparable or even lower resistance than the desired "C-mode".
- And finally there are the higher overtones of the low frequency vibration modes such as face-shear mode etc. Those can interfere with the main mode within a small temperature interval and will cause frequency dips and activity dips ("band breaks")
If you try to build an oscillator with overtone crystals you must always include a kind of trap or other selective circuits to allow only the desired overtone to work. For an oscillator using a SC-cut crystal you need to add additional selectivity to avoid operation at (or jumping to) the B-mode. This could be very tricky.
Best regards
Bernd
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag von Dana Whitlow
Gesendet: Samstag, 29. Februar 2020 00:47
Many crystals possess spurious modes not terribly far from the desired Hi-Q mode.
Since the spurious mode(s) are lower Q, oscillation on one of these can build up faster than oscillation in the desired mode, driving the sustaining amplifier into compression before the desired oscillating mode really gets going. This will leave only the fastest-growing mode as the winner. This is not speculation- I've seen it happen.
My point is that just building an oscillator with an unknown crystal has no assurance of running where you really want it to, thus leading you astray.
Discovering all these
modes is a big part of the benefit of studying the crystal with a VNA or similar instrument before building anything. Forewarned is forearmed- you then have a better chance of building an oscillator that does what you want it to do.
Dana
Hi
As long as we are beating up on the poor old SC for mode issues:
We have an C mode ( = the one that normally gets used in a precision oscillator)
We have a B mode ( = the “thermometer” mode that gets used in some MCXO’s)
Hmmm …. why did they start with B … hmmm ….
Well yes indeed there is an A mode. For a given overtone it’s above the B mode.
Exactly why they are lettered high to low … at least they are in order.
Page 3-15 in:
Quartz Resonator & Oscillator Tutorial - Time and Frequency ...tf.nist.gov › sim › 2010_Seminar › vig3 https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=2ahUKEwiYxa7Z-vbnAhWJlnIEHaTSCAkQFjABegQIARAB&url=https%3A%2F%2Ftf.nist.gov%2Fsim%2F2010_Seminar%2Fvig3.ppt&usg=AOvVaw0LXXz8jKe0sNHtk3Cj18ok
Gives a nice plot of how it fits in. Why mention it? Well it’s the answer to the next up
question “why is the oscillator passband so tight?” ( = you have to kill a very close mode just above
the 3rd OT C mode and a closer than you would think mode below it).
Bob
On Feb 29, 2020, at 6:30 AM, Bernd Neubig BNeubig@t-online.de wrote:
You are right. As I am usually stating in my crystal seminars: "You are ordering a crystal with one particular frequency, but the manufacturer supplies with the crystals free of charge a bunch of additional frequencies, which are not mentioned on the marking."
There is a multitude of spurious in real crystals:
- So-called an-harmonic spurious resonances, which are all above the desired frequency. For plano-convex crystals, as the usual high-precision overtone crystals at 5 MHz or 10 MHz, there are two or three (at least) very strong spuriii about 100 kHz ~ 200 kHz above. In poorly designed crystals these modes could be as strong or even stronger than the main mode.
- The other overtones including the fundamental mode with their an-harmonics are also always present. Higher overtones usually have higher resistance than the main mode, but the fundamental mode of a 3rd overtone could have a lower resistance than the desired 3rd OT. The B-Mode is a temperature sensor mode with -30 ppm/K f(T) slope
- SC-cut crystals have a strong "B-mode only 9% above the main mode, which has comparable or even lower resistance than the desired "C-mode".
- And finally there are the higher overtones of the low frequency vibration modes such as face-shear mode etc. Those can interfere with the main mode within a small temperature interval and will cause frequency dips and activity dips ("band breaks")
If you try to build an oscillator with overtone crystals you must always include a kind of trap or other selective circuits to allow only the desired overtone to work. For an oscillator using a SC-cut crystal you need to add additional selectivity to avoid operation at (or jumping to) the B-mode. This could be very tricky.
Best regards
Bernd
-----Ursprüngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces@lists.febo.com] Im Auftrag von Dana Whitlow
Gesendet: Samstag, 29. Februar 2020 00:47
Many crystals possess spurious modes not terribly far from the desired Hi-Q mode.
Since the spurious mode(s) are lower Q, oscillation on one of these can build up faster than oscillation in the desired mode, driving the sustaining amplifier into compression before the desired oscillating mode really gets going. This will leave only the fastest-growing mode as the winner. This is not speculation- I've seen it happen.
My point is that just building an oscillator with an unknown crystal has no assurance of running where you really want it to, thus leading you astray.
Discovering all these
modes is a big part of the benefit of studying the crystal with a VNA or similar instrument before building anything. Forewarned is forearmed- you then have a better chance of building an oscillator that does what you want it to do.
Dana
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