[time-nuts] Looking for datasheet for Oscilloquartz 8602

[Jim Lux]

On 5/28/13 9:29 AM, Bob Camp wrote:
> Hi
>
> The cost of a BVA oscillator is primarily a function of the cost of the
> blank used and secondarily a function of the resonator processing. You see
> numbers in the $200 to $400 range tossed around for the blank (vs < $10 for
> a good SC blank). The packaged resonator starts looking like $600 to $900
> once you have that sort of blank in it (vs < $20 for a similar SC). BVA's
> are never going to be cheap or plentiful.
>
> I think you will find a number of people selling 5 MHz OCXO's in the -110 to
> -120 dbc/Hz at 1 Hz range. That's not really where the BVA is needed. It's
> benefit is more in the 0.1 or 0.01Hz phase noise. Put another way, ADEV is
> the better tool to rate a BVA.
>
> If you really want to get any resonator (or even an atomic standard) to look
> good on ADEV at 1 to 10,000 seconds, it needs to be temperature stable.
> Either it needs a really good oven, or you need a lab that doesn't change
> temperature. For good ADEV in a normal environment, that means a "hockey
> puck" style single oven, or a good double oven. Again, a cost adder /
> greater scarcity thing.
>
> Given all that, a BVA that gives you < 1x10^-13 from 1 to >1,000 seconds in
> a normal lab is a very rare item. What ever the cost, it's going to be
> pretty steep.
>



The USO's we got for GRAIL from APL have ADEV<1E-13 from 1 to 1000 
seconds, and then heads up at 1 decade/decade.  The lowest ADEV is about 
5E-14 at around 50 seconds, but it's pretty flat.  See the paper by 
Enzer et al.

Or better, the 42ns PTTI conference paper by Greg Weaver at APL, who had 
to build them.

They are space qualified, so they're fairly pricey (>$1M a copy).  But 
to put the discussion about blanks and finished product.. I think they 
started around 1000 blanks to produce a few dozen packaged crystals, 
which were then run as oscillators to see which ones were the best, 
producing maybe four final pieces, 2 at each frequency.

The Weaver PTTI paper compares these to the BVA resonators.. SC cut 
5MHz, 3rd overtone.

They run in a vacuum bottle (of course), and they have somewhat 
obsessive attention to a lot of details.  But I suspect that aside from 
the space qual aspects, the whole "how you build them" isn't a whole lot 
different.

Very much an art at many steps along the way. There are people at the 
crystal houses who have been working on these things since the days of 
Transit.