This all seems to be forgetting that the crystals are usually operated
at 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd
overtone. A high quality 5 MHz/5th overtone crystal is really a 1 MHz
fundamental, a large piece of quartz. Running at a harmonic greatly
reduces the influence of the package.
David
On 11/2/13 1:07 AM, Bob Camp wrote:
Hi
The real answer is that nobody knows. The economics essentially make finding
out very expensive. Q most certainly goes up, I don’t think anybody disputes
that. The questions about flicker / ADEV all revolve around small blank parts
with major edge sensitivity issues. They also probably were not running in a
very good oven. Unless somebody with very deep pockets decides they need to
find out, it’s going to be an un-answered question.
Bob
On Nov 1, 2013, at 11:41 PM, Richard (Rick) Karlquist <rich...@karlquist.com>
wrote:
On 11/1/2013 8:28 PM, Bob Camp wrote:
HI
If you doubled the diameter of the blank each time you cut the frequency in
half, all sorts of nice things might happen. If you start with a 1/2” blank in
at 10 MHz that goes to 1” at 5 MHz and 2” at 2.5 MHz. Around 1 MHz you would
get to a 5” blank.
Good luck finding high grade quartz bars to cut 5” (or even 1”) blanks out of.
You are going to have to go back to the autoclave fixtures at the very least.
Since growth is (at best) linear you cost of quartz will scale with the size of
the blank. I’d bet it scales a bit more than that if you want to keep the
material at a high level of performance.
You've explained the excuses vendors give for not making full
size crystals. But the question is, given these realities,
does this reduce the theoretical advantage of the lower frequency
and by how much?
Rick Karlquist N6RK
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