| Author |
Message |
John Woodgate
Guest
|
 Posted:
Tue Mar 01, 2005 6:55 pm Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
I read in sci.electronics.design that Paul Burke <paul@scazon.com> wrote
(in <38j07rF5o6pl4U1@individual.net>) about 'Using non-overtone crystal
in overtone mode?', on Tue, 1 Mar 2005:
| Quote: | John Woodgate wrote:
OK, silly I know, but I cant figure out YMMV...
Year 2005. (;-)
Honestly John! That should be AMMV.
|
The promulgation of a 'horrible hybrid' is justified in pursuit of a
whimsical coincidence.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
|
|
| Back to top |
|
 |
John Fields
Guest
|
| Posted:
Tue Mar 01, 2005 8:04 pm Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
On Mon, 28 Feb 2005 18:33:53 -0800, "RST Engineering"
<jim@rstengineering.com> wrote:
| Quote: | That is total and absolute bullpuckey.
Jim
---
You can use a fundamental mode crystal as an overtone oscillator, but
even if you can get it to oscillate, it won't be generating an
overtone at 100MHz, since overtone modes of oscillation aren't
harmonically related to the fundamental.
|
---
RST what???
--
John Fields |
|
| Back to top |
|
|
douglas dwyer
Guest
|
| Posted:
Tue Mar 01, 2005 8:13 pm Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
In message <1eb84d4a.0502281507.73ff7c41@posting.google.com>, Frank Moe
<moesenpeter@gmx.de> writes
| Quote: | There are also manufacturers that make 100 in fundamental (up to about
200MHz), and many should have 100 in 5th as standard part...
High frequency fundamentals are real and can be purchased to at least |
250MHz note they are expensive, their Q which is ultimately material
related reduces with increased frequency (loss is per cycle) such that
it may be no higher than a SAW resonator . Still better than a SAW as
the temperature coefficient for the SAW only has the linear cancelled
whereas the AT cut has the parabolic term cancelled.
Finally the 5th overtone will only pull 1/25 times the fundamental.
Finally finally the SAW can be run at much higher power levels so noise
floor is much better.
Finally finally finally a SAW needs a mask which gives a high up front
cost and lead time.
The difference in frequency for overtone /X fund may be much more than
2000ppm where the plate is not very parallel and the plate back and
electrode diameter non optimum. Beware AT cut strip crystals ie a long
section of a circular diameter these may not like overtone operation.
not pull with external reactance change perhaps a byt
--
dd
|
|
| Back to top |
|
|
douglas dwyer
Guest
|
| Posted:
Tue Mar 01, 2005 8:18 pm Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
In message <OhfGOYBPeDJCFwJT@jmwa.demon.co.uk>, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> writes
| Quote: | I remember being told by a crystal 'expert' that with some cuts the
difference can be much larger than that. Is that so?
Yes depends on electrode diameter plate diameter plate back (electrode |
thickness) and parallelism. ie I would not be surprised at 10000ppm.
--
dd |
|
| Back to top |
|
|
Harold E. Johnson
Guest
|
| Posted:
Tue Mar 01, 2005 8:40 pm Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
Hi Doug, great to hear from you and the info in your posts. I'm currently
using a SAW at 660 MHz for the clock in a 9951 DDS. Actually, it's better
than my 200 MHz 7th overtone tripled to 660 with an MMIC although I do think
my MMIC tripler is most of the culprit.
Reason for the post, I think you've changed ISP's on me again, my mail to
you gets bounced. Would you pse address me a short note to the e-mail
address and give me the current one? That is, if it's not me you're trying
to get rid of!
Regards
W4ZCB |
|
| Back to top |
|
|
Robert Scott
Guest
|
| Posted:
Tue Mar 01, 2005 8:57 pm Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
| Quote: | You can use a fundamental mode crystal as an overtone oscillator, but
even if you can get it to oscillate, it won't be generating an
overtone at 100MHz, since overtone modes of oscillation aren't
harmonically related to the fundamental.
|
There is a related phenomenon in the field of piano tuning. It has
long been known that overtones (called "partials" by piano people) of
piano notes are not exactly related to pitch of the fundamental
frequency by whole numbered ratios. Instead they are related by
factors like
1.000
2.003
3.007
4.018
5.039
6.092
7.211
etc.
The amount by which this series deviates from the ideal whole-numbered
ratios is called "inharmonicity" and it differs from one string to
another. The stiffer the string, the more inharmonicity. Long thin
strings, as are found on harpsichords, have almost no inharmonicity.
Short strings in the highest section of the piano have the most
inharmonicity. Since one of the goals of piano tuning is to make
partials of different notes come out the same, this phenomenon of
inharmonicity makes piano tuning inherently more difficult than
instruments that have no inharmonicity, like pipe organs.
What is perhaps more like quartz crystals is carillon bells. They are
tuned at the factory, and each partial is tuned independently and
separately by grinding away metal from different levels on the bell.
In view of these related phenomena, it is no wonder that overtones of
quartz crystals are independent of each other and from the
fundamental.
-Robert Scott
Ypsilanti, Michigan |
|
| Back to top |
|
|
RST Engineering (jw)
Guest
|
| Posted:
Tue Mar 01, 2005 10:12 pm Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
Sorry, dude, 50 years of designing with crystals, right from when I ground
my first surplus WWII rock on a piece of glass with toothpaste as the
abrasive says that what the original poster asked is correct.
Will the harmonic be precise? No. Will it be "close", which is what the
original poster asked? You bet. Depending on the oscillator circuit, can
it be "pulled" on frequency? Perhaps.
But to say that the crystal doesn't resonate anywhere near the harmonic is,
as I said, bullpuckey.
Jim
"Terry Given" <my_name@ieee.org> wrote in message
news:keSUd.5425$1S4.590975@news.xtra.co.nz...
| Quote: | RST Engineering wrote:
That is total and absolute bullpuckey.
Jim
sorry dude, 50 years of IEEE UFFC papers suggest *you* are wrong. I was
surprised when I learned this too.
Cheers
Terry |
|
|
| Back to top |
|
|
John Fields
Guest
|
| Posted:
Tue Mar 01, 2005 10:57 pm Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
On Tue, 1 Mar 2005 08:12:48 -0800, "RST Engineering \(jw\)"
<jim@rstengineering.com> wrote:
| Quote: | Sorry, dude, 50 years of designing with crystals, right from when I ground
my first surplus WWII rock on a piece of glass with toothpaste as the
abrasive says that what the original poster asked is correct.
Will the harmonic be precise? No. Will it be "close", which is what the
original poster asked? You bet. Depending on the oscillator circuit, can
it be "pulled" on frequency? Perhaps.
But to say that the crystal doesn't resonate anywhere near the harmonic is,
as I said, bullpuckey.
|
---
Sorry, dude, no matter how much time you've got in, if you go back
and read my post, you'll find that I wrote:
"You can use a fundamental mode crystal as an overtone oscillator, but
even if you can get it to oscillate, it won't be generating an
overtone at 100MHz, since overtone modes of oscillation aren't
harmonically related to the fundamental."
and that you replied with:
"That is total and absolute bullpuckey."
Notice that I didn't say "near", I said "at".
If you can find fault with anything I wrote in that post, I'd
appreciate specific criticism instead of that broad brush you painted
with.
--
John Fields |
|
| Back to top |
|
|
Joerg
Guest
|
| Posted:
Wed Mar 02, 2005 1:24 am Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
Hello John,
| Quote: | "You can use a fundamental mode crystal as an overtone oscillator, but
even if you can get it to oscillate, it won't be generating an
overtone at 100MHz, since overtone modes of oscillation aren't
harmonically related to the fundamental."
|
When you look at older (pre-PLL) VHF communication gear of the more
professional kind they didn't use 5th or higher overtones but employed
frequency multiplier stages. For good reason, one being the offset you
had mentioned. I'd never run a crystal on its umpteenth harmonic and
always designed in multiplier stages like the radio folks did. With
today's cheap logic chips that doesn't even cost much in extra parts.
| Quote: | and that you replied with:
"That is total and absolute bullpuckey."
|
Look on the bright side. Some of us, including me, didn't know the
expression "bullpuckey". I got a kick out of it.
Regards, Joerg
http://www.analogconsultants.com |
|
| Back to top |
|
|
Don Klipstein
Guest
|
| Posted:
Wed Mar 02, 2005 1:30 am Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
In article <11295445so5g311@corp.supernews.com>, RST Engineering \(jw\) wrote:
| Quote: | Sorry, dude, 50 years of designing with crystals, right from when I ground
my first surplus WWII rock on a piece of glass with toothpaste as the
abrasive says that what the original poster asked is correct.
Will the harmonic be precise? No. Will it be "close", which is what the
original poster asked? You bet. Depending on the oscillator circuit, can
it be "pulled" on frequency? Perhaps.
But to say that the crystal doesn't resonate anywhere near the harmonic is,
as I said, bullpuckey.
|
This reminds me of a colleague who can easily tell everyone
qualitatively that a situation deviates from theoretical ideals and as a
result (using my words and not his) "$#!+ (poop) will splatter!" But he
at least often in my experience have trouble saying this quantatively!
For one project, I decide to try something, and tell my boss what I am
trying. This colleague of mine says (using words of mine and not his),
"slop will spatter"! (As in light for adding optics to a light source for
a specific application. This application has multiple LEDs shining onto
an optical device with multiple elements.)
Boss tells me that what I delivered to him and he found working should
not have worked according to this colleague of mine, due to stray beams
forming. So what do I do - I send photos to the boss of the beam pattern
including the stray beams predicted by my colleague. I even named these
stray beams after my colleague. But they were minor due to most light
produced by the light source being on paths that resulted in adding to the
desired beam combination as opposed to the undesired stray beams.
Furthermore, my boss's industrial designer designed a baffling system
that blocked the small amount of light from the multi-element light source
that was on paths towards the stray beams as opposed to the desired rays
that were "on course" to be utilized by the multi-elemt optical assembly
as planned.
So beware that the situation may not be much worse than ideal when
someone can tell you how you are deviating from ideal! |
|
| Back to top |
|
|
Don Klipstein
Guest
|
| Posted:
Wed Mar 02, 2005 1:41 am Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
In article <ts6921d632jtuabnv9d0n9b0hv5mlb573i@4ax.com>, John Fields wrote:
| Quote: | On Tue, 1 Mar 2005 08:12:48 -0800, "RST Engineering \(jw\)"
jim@rstengineering.com> wrote:
Sorry, dude, 50 years of designing with crystals, right from when I ground
my first surplus WWII rock on a piece of glass with toothpaste as the
abrasive says that what the original poster asked is correct.
Will the harmonic be precise? No. Will it be "close", which is what the
original poster asked? You bet. Depending on the oscillator circuit, can
it be "pulled" on frequency? Perhaps.
But to say that the crystal doesn't resonate anywhere near the harmonic is,
as I said, bullpuckey.
---
Sorry, dude, no matter how much time you've got in, if you go back
and read my post, you'll find that I wrote:
"You can use a fundamental mode crystal as an overtone oscillator, but
even if you can get it to oscillate, it won't be generating an
overtone at 100MHz, since overtone modes of oscillation aren't
harmonically related to the fundamental."
and that you replied with:
"That is total and absolute bullpuckey."
Notice that I didn't say "near", I said "at".
If you can find fault with anything I wrote in that post, I'd
appreciate specific criticism instead of that broad brush you painted
with.
|
Now suppose someone makes a crystal oscillate in some overtone mode that
the crystal manufacturer recommends against and is predicted to be
"inharmonic" but turns out to be only a few hundred or even sometimes a
few 10's of KHz from a multiple of a frequency that results from being
used as directed?
As I said in different words in a different post - correctly predicting
that $#!+ (AKA "slop") will spatter does not necessarily that much will
spatter nor that any will spatter far, and maybe in many cases it is
doubtful that both much will spatter and that much will spatter far.
- Don Klipstein (don@misty.com) |
|
| Back to top |
|
|
Tim Shoppa
Guest
|
| Posted:
Wed Mar 02, 2005 2:34 am Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
Harold Johnson wrote:
| Quote: | I'm currently
using a SAW at 660 MHz for the clock in a 9951 DDS.
|
Interesting factoid: I was looking to experiment with 100MHz
oscillators largely as a clock source for my own AD9951 experimentation
(using the AD9951's built-in PLL multiplier at 4x). I was hoping to
experiment a bit with 20 MHz crystals I already had in hand before
ordering some "real overtone" crystals cut just for me. I've been
looking at AD app note AN-419 and it's Butler oscillator, in
particular, although the clock input of the AD9951 probably has
different requirements than the AD9850 targetted in AN-419.
Does the AD9951 really work at 660MHz? I thought it was only good to
400MHz...
So far my experimenting has used the on-chip oscillator at 25MHz and
the PLL at 16x to get to 400MHz.
| Quote: | Actually, it's better
than my 200 MHz 7th overtone tripled to 660
|
We bandied about "non-harmonic" relations here but how you get from 200
to 660, I don't know.
Tim. |
|
| Back to top |
|
|
Harold E. Johnson
Guest
|
| Posted:
Wed Mar 02, 2005 3:44 am Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
| Quote: | Interesting factoid: I was looking to experiment with 100MHz
oscillators largely as a clock source for my own AD9951 experimentation
(using the AD9951's built-in PLL multiplier at 4x). I was hoping to
experiment a bit with 20 MHz crystals I already had in hand before
ordering some "real overtone" crystals cut just for me. I've been
looking at AD app note AN-419 and it's Butler oscillator, in
particular, although the clock input of the AD9951 probably has
different requirements than the AD9850 targetted in AN-419.
|
The built-in multiplier is quite noisy and makes the 9951 run terribly hot.
| Quote: |
Does the AD9951 really work at 660MHz? I thought it was only good to
400MHz...
|
Yes, if you DON'T use the on board multiplier. I've had it to 750 MHz just
to check it since I had heard of some DL's overclocking it to that
frequency. Properly heat sunk to the eval board, and without the multiplier,
it's cool as a cucumber. AD rates it only to 400 MHz but a sample of 6 units
all operate well at 660 MHz.
| Quote: |
So far my experimenting has used the on-chip oscillator at 25MHz and
the PLL at 16x to get to 400MHz.
Actually, it's better
than my 200 MHz 7th overtone tripled to 660
We bandied about "non-harmonic" relations here but how you get from 200
to 660, I don't know.
|
Well, this one is a 220 MHz 7th overtone from ICL specially surface treated
for low noise and operating in a Stephensen bipolar/FET Butler. But as I
mentioned to Doug, afraid my MMIC tripler makes a bad job of the 660 output
despite a 3 pole final filter. The SAW is not near the Q of the crystal, but
the SNR is much better.
Regards
W4ZCB |
|
| Back to top |
|
|
douglas dwyer
Guest
|
| Posted:
Wed Mar 02, 2005 4:58 am Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
In message <mj3Vd.8232$OU1.3254@newssvr21.news.prodigy.com>, Joerg
<notthisjoergsch@removethispacbell.net> writes
| Quote: |
When you look at older (pre-PLL) VHF communication gear of the more
professional kind they didn't use 5th or higher overtones but employed
frequency multiplier stages. For good reason, one being the offset you
had mentioned. I'd never run a crystal on its umpteenth harmonic and
always designed in multiplier stages like the radio folks did. With
today's cheap logic chips that doesn't even cost much in extra parts.
Often cheaper to multiply up than buy an expensive 5th overtone that was |
difficult to pull onto frequency and fussy to set up.
The exception would be current and size saving for some portables.
--
dd |
|
| Back to top |
|
|
Joerg
Guest
|
| Posted:
Wed Mar 02, 2005 6:10 am Post subject:
Re: Using non-overtone crystal in overtone mode? |
|
|
Hello Douglas,
| Quote: | Often cheaper to multiply up than buy an expensive 5th overtone that
was difficult to pull onto frequency and fussy to set up.
|
And these special cuts can indeed be fussy. They can also be a
procurement nightmare.
| Quote: | The exception would be current and size saving for some portables.
|
Even then it could be done. Besides the discrete solution there are
blazingly fast logic inverters such as the ALVC series. These are
usually under 20 cents and come in the super tiny TSSOP format. Now I
just wish they had unbuffered versions to do the oscillator part with.
If a 74HCU04 is needed for other jobs on the board it could run the
oscillator but for any reasonable speed these require more than 4V.
Regards, Joerg
http://www.analogconsultants.com |
|
| Back to top |
|
|
|
|
|
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in