Bernd, thanks for the excellent treatment on the subject
glen
On 21/09/2019 4:42 PM, Bernd Neubig wrote:
Hi,
There is nothing like a fixed ratio between R1 at 3rd or 5th overtone the R1
at fundamental mode. The best approach through C1 and Q.
C1 reduces with the square of overtone N (for
An: 'Discussion of precise time and frequency measurement'
Betreff: AW: [time-nuts] overtone crystal question
Hi,
There is nothing like a fixed ratio between R1 at 3rd or 5th overtone the R1
at fundamental mode. The best approach through C1 and Q.
C1 reduces with the square of overtone N
Hi,
There is nothing like a fixed ratio between R1 at 3rd or 5th overtone the R1
at fundamental mode. The best approach through C1 and Q.
C1 reduces with the square of overtone N (for an infinite crystal plate). In
reality C1(3rds about 85% of C1(fund/N^2. For the 5th and higher OT it is about
Hi
You “shape” the blank to trap energy on some crystals. Also the energy
distribution on the blank changes with overtone. You can change the electrodes
to get more of “what you want” and less of “what does not matter”. Plating
thickness
also gets optimized based on overtone. There are a long
kb...@n1k.org said:
> ( If I want a good 3rd overtone, it will be designed to work well there. It
> may be pretty bad on the fundamental â¦.).
Thanks.
What sort of things would you do to a crystal to make it work well at 3rd
overtone and/or why do they make operation at the fundamental worse?
Hi Bob
thanks for the insight.
OK so the Rm for an overtone crystal , measured at the fundamental might
be a bad indicator of the overtone Rm. I have found empirically, a
loose relationship of Rm proportional to overtone number from the
fundamental. But loose- I mean +/- 50% which, as you
Hi
Bottom line - if you are designing a filter, you need the real values for
the Cm, Lm and C0. Guessing at them is likely to lead to trouble if it is
a reasonably complex filter.
Rm generally goes as the overtone. It can deviate quite a bit from that
(as can the other parameters) depending
I wonder if anyone can shed any light on this question, since this forum
is loaded with those who REALLY understand crystals.
I am modeling crystal filters (VHF) in SPICE. There are some specific
acoustic mode models for SPICE in some Post Doctorial papers, very
interesting, they would be
