Risto Tiilikainen wrote:

JJ wrote:

"Highest performance"? Is that output amplitude? Or minimum startup
time? Or startup reliability? Or lowest power requirement? Or what?

Jitter, that's a little easier to define but it's usually not the most
relevant parameter in radio. It is related to sideband and phase noise
and in fact cannot be completely decoupled from either.


tor :-)


Tim KA0BTD





Its not for a radio. I want to minimize the cycle to cycle variations
in timing and it should be simple enough to make with 1 or 2
transitors. So not looking for NASA spec stuff, just reliable so it
starts every time.

JJ


Hi !

Any of those oscillators is OK if resonance circuit Q is kept high and
oscillation power in average low level.
High Q will guarantee easy and fast starting every time
Average low level keeps components cool and cycle to cycle variations
are reduced
Third important question is loading the oscillator.
High impedance FET buffer which is not galvanic ally connected to
oscillator is very good solution.
The gate of buffer FET can be provided with an "antenna" wire
collecting tiny energy from the oscillator resonance circuit.
This kind of loose coupling guarantees that effects of external
variations are minimized.

These principles also guarantee that buffer will amplify 1st order and
upper harmonics are powerfully reduced (in oscillator and in first
buffer)
I have experienced superior results with these guidelines when
constructing LC oscillators

73, Risto OH2BT

HI !
Sorry . I read again your subject.
You were asking from crystal oscillators and I began to explain LC
oscillators
Risto

Risto Tiilikainen wrote in
:


Hi !

Any of those oscillators is OK if resonance circuit Q is kept high and
oscillation power in average low level.
High Q will guarantee easy and fast starting every time
Average low level keeps components cool and cycle to cycle variations
are reduced
Third important question is loading the oscillator.

73, Risto OH2BT
Good info thanks. What are other crystal series oscillators besides Butler
type?

JJ

If it oscillates it doesn't matter about the type of oscillator
circuit.

There's no need to worry yourself.

Performance all depends on the cut of the crystal which you have
already decided upon without giving it much thought.

Just connect it up in the most simple circuit and away you go.
----
Reg.

======================================

"Reg Edwards" wrote in news:dt8a26$hs7$1
@nwrdmz03.dmz.ncs.ea.ibs-infra.bt.com:

If it oscillates it doesn't matter about the type of oscillator
circuit.

There's no need to worry yourself.
----
Reg.

======================================
There is a drop in freq for Pierce and Colpitt after 1 min of startup. Can
be 100Hz.
Serious enough.

JJ

There is a drop in freq for Pierce and Colpitt after 1 min of startup. Can
be 100Hz.
Serious enough.
-------------------------------------

Not true.

100 Hz is a huge variation by crystal standards, especially in the lower
frequency ranges. If a crystal oscillator drifts substantially during
warmup, it usually implies two things:

1) The oscillator is driving the "so-called" parallel resonance of the
crystal, which is very dependent on circuit capacitance. I said "so-called"
because the parallel resonance isn't really a true resonance of the quartz,
it's a frequency where the crystal appears inductive enough to resonate the
combinationo fo the holder capacitance and the circuit capacitance.

2) The circuit is poorly designed.

BTW, some here have suggested just purchasing a 'can' oscillator. Be very
careful of these, and check the specs carefully. Many 'can' oscillators have
an internal programmable RC VCO that is PLL locked to a low frequency
crystal. The up-side is that the manufacturer will make any frequency you
want (some are even user-programmable). The down side is that RC VCO's have
horrible jitter ('phase noise') that isn't corrected by the PLL


Joe
W3JDR

ORIGINAL MESSAGE:

JJ wrote:

There is a drop in freq for Pierce and Colpitt after 1 min of
startup. Can be 100Hz.
Serious enough.

JJ

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sounds like you're driving the crystal too hard and it's heating up.
When something heats it expands and a larger crystal has a lower
frequency. If you want best stability, reduce the drive until the
circuit barely oscillates and make up the lower output with a stage of
amplification.

73, Bill W6WRT

JJ wrote:
There is a drop in freq for Pierce and Colpitt after 1 min of startup. Can
be 100Hz.
Serious enough.

That sounds like crystal heating. All of these oscillators can drive
the crystal at various drive levels (depending on resistor and
capacitor values and/or tank circuit tapping) and different crystals
like different drive levels.

A tuning-fork type crystal (e.g. 32kHz watch crystal) is being
overdriven if the levels are as high as a microwatt.

Most HF-range crystals will take hundreds of microwatts to a few
milliwatts of drive.

Lots of the oscillator circuits in old handbooks are designed around
FT-243 crystals, which can take substantially higher drive levels
(sometimes the tube oscillator was putting out several watts) than
"modern" crystals. And even then those handbook circuits overdrove the
crystals to get more power out of the oscillator! By 1950's standards
100Hz of chirp/drift was not a big deal (was probably better than
average for most equipment.)

Tim.

JJ wrote:
Risto Tiilikainen wrote in
:


Hi !

Any of those oscillators is OK if resonance circuit Q is kept high and
oscillation power in average low level.
High Q will guarantee easy and fast starting every time
Average low level keeps components cool and cycle to cycle variations
are reduced
Third important question is loading the oscillator.

73, Risto OH2BT

Good info thanks. What are other crystal series oscillators besides Butler
type?

JJ

One type not mentioned is the Franklyn, which IIRC is a cross coupled
multivibrator with one feedback path through the rock.