In article , RST Engineering \(jw\) 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.

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!

On Mon, 28 Feb 2005 18:33:53 -0800, "RST Engineering"
wrote:

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

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

"John Fields" bravely wrote to "All" (28 Feb 05 14:34:30)
--- on the heady topic of " Using non-overtone crystal in overtone mode?"

JF From: John Fields
JF sci.electronics.components:12029 rec.radio.amateur.homebrew:8635

JF Check out "Chladni patterns" if you're interested.

I've done some putzing with crystals. What frequency say would a
100.3MHz xtal in series with a 100.1Mhz xtal settle on? 100.2Hz?

A*s*i*m*o*v

.... It's kind of fun to do the impossible... -Walt Disney

Depending on whether the circuit is designed for overtone oscillation or
harmonic generation, how perfect the overtone crystals are, and how the
circuit is tuned, I'd expect either:
1) No oscillation
2) Very close to 100.1 MHz
3) Very close to 100.3 MHz

What did you experience?

Joe
W3JDR


"Asimov" wrote in message
...
"John Fields" bravely wrote to "All" (28 Feb 05 14:34:30)
--- on the heady topic of " Using non-overtone crystal in overtone
mode?"

JF From: John Fields
JF sci.electronics.components:12029 rec.radio.amateur.homebrew:8635

JF Check out "Chladni patterns" if you're interested.

I've done some putzing with crystals. What frequency say would a
100.3MHz xtal in series with a 100.1Mhz xtal settle on? 100.2Hz?

A*s*i*m*o*v

... It's kind of fun to do the impossible... -Walt Disney

"W3JDR" bravely wrote to "All" (01 Mar 05 10:34:17)
--- on the heady topic of " Using non-overtone crystal in overtone mode?"

It did oscillate. I was some really oddball frequency inbetween but as
I recall it was neither the mean nor any other obvious relation. I
suppose it was where their response curves complimented but I'm not
sure. Did it only for curiosity's sake to see if it they could be used
for filtering but tried making them oscillate for fun. I know, simple
pleasures... ;-)

A*s*i*m*o*v


W3 Reply-To: "W3JDR"
W3 Xref: aeinews rec.radio.amateur.homebrew:8665

W3 Depending on whether the circuit is designed for overtone oscillation
W3 or harmonic generation, how perfect the overtone crystals are, and how
W3 the circuit is tuned, I'd expect either:
W3 1) No oscillation
W3 2) Very close to 100.1 MHz
W3 3) Very close to 100.3 MHz

W3 What did you experience?

W3 Joe
W3 W3JDR


W3 "Asimov" wrote in
W3 message ...
"John Fields" bravely wrote to "All" (28 Feb 05 14:34:30)
--- on the heady topic of " Using non-overtone crystal in overtone
mode?"

JF From: John Fields
JF sci.electronics.components:12029 rec.radio.amateur.homebrew:8635

JF Check out "Chladni patterns" if you're interested.

I've done some putzing with crystals. What frequency say would a
100.3MHz xtal in series with a 100.1Mhz xtal settle on? 100.2Hz?


.... All things are possible. Except skiing through a revolving door.

Was it crystal-locked, or free-running....did it change frequency when you
tuned the circuit? If it wasn't crystal locked, then the experiment wasn't
too meaningful

Joe
W3JDR

"Asimov" wrote in message
...
"W3JDR" bravely wrote to "All" (01 Mar 05 10:34:17)
--- on the heady topic of " Using non-overtone crystal in overtone
mode?"

It did oscillate. I was some really oddball frequency inbetween but as
I recall it was neither the mean nor any other obvious relation. I
suppose it was where their response curves complimented but I'm not
sure. Did it only for curiosity's sake to see if it they could be used
for filtering but tried making them oscillate for fun. I know, simple
pleasures... ;-)

A*s*i*m*o*v


W3 Reply-To: "W3JDR"
W3 Xref: aeinews rec.radio.amateur.homebrew:8665

W3 Depending on whether the circuit is designed for overtone oscillation
W3 or harmonic generation, how perfect the overtone crystals are, and
how
W3 the circuit is tuned, I'd expect either:
W3 1) No oscillation
W3 2) Very close to 100.1 MHz
W3 3) Very close to 100.3 MHz

W3 What did you experience?

W3 Joe
W3 W3JDR


W3 "Asimov" wrote in
W3 message ...
"John Fields" bravely wrote to "All" (28 Feb 05 14:34:30)
--- on the heady topic of " Using non-overtone crystal in overtone
mode?"

JF From: John Fields
JF sci.electronics.components:12029 rec.radio.amateur.homebrew:8635

JF Check out "Chladni patterns" if you're interested.

I've done some putzing with crystals. What frequency say would a
100.3MHz xtal in series with a 100.1Mhz xtal settle on? 100.2Hz?


... All things are possible. Except skiing through a revolving door.

In article ,
John Fields 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. It's more like the slab of
crystal is vibrating like the drumhead of a steel drum with small
areas of the slab vibrating at higher frequencies, instead of the
entire slab virbarting at just one frequency.

No, its more like a jello when you jiggle the dish side to side. The main
action of an AT cut is shear mode. In the harmonics, the motion looks
kind of like this:









If you think about the top two lines of text in my little drawing. I
think it is obvious that if the maker thinned it down by one line of text
just as you come to the edge, that portion of the crystal would not work
well at this harmonic. This is what they do in crystals intended for
fundamental operation. It knocks that activity down by several dB at the
overtone. This makes it very unlikely that a simple oscillator will take
off at an overtone.
--
--
forging knowledge

I don't know why off-the-shelf crystals are needed when Jan Crystal (Ft.
Myers FL) will make the crystal to your specifications in a few days for the
same amount of money. They can do fifth ot at 100 MHz. quite easily.

Jim



If anyone knows of a place that ships off-the-shelf 100 MHz fifth or
seventh overtone crystals, I can avoid this whole exercise.... :-)

Tim.

On Mon, 28 Feb 2005 13:29:15 -0800, "RST Engineering \(jw\)"
wrote:

I don't know why off-the-shelf crystals are needed when Jan Crystal (Ft.
Myers FL) will make the crystal to your specifications in a few days for the
same amount of money. They can do fifth ot at 100 MHz. quite easily.

Jim



If anyone knows of a place that ships off-the-shelf 100 MHz fifth or
seventh overtone crystals, I can avoid this whole exercise.... :-)

Tim.


a CB xtal will probably operate on 100MHz, althouth I've only seen
applications for 45 and 81MHz

-jm

---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm