[time-nuts] Bye-Bye Crystals

Jeff AC0C keepwalking188 at ac0c.com
Mon Mar 13 20:03:02 EDT 2017

Making a finished crystal, especially a high-Q one of a target frequency far 
removed from the 8-10 Mhz sweet spot, is definitely one of those projects 
that is a lot harder than you would think it is.  I was down at ICM a few 
years back when we were building some high-Q 70 Mhz VHF crystals for a 
filter project and it was amazing the amount of stuff they had there.


-----Original Message----- 
From: Bob Camp
Sent: Monday, March 13, 2017 5:19 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Bye-Bye Crystals


…. ummm …. errr … Add to that:

X-ray gear to work out the orientation of the (possibly natural) bar you are 
Lapping gear to get the blanks flat (as optically flat)
Automated / sorting X-ray gear to figure out what’s what after they are 
Rounding equipment to turn the square ones into round ones without damaging 
Contouring gear to put the proper shape on one or both sides (or pipes)
Polishing gear to finish the shaping process
Etching baths to get the surface to it’s final condition
High vacuum cleaning to get all the crud off of all the parts before you do 
much of anything with themA base plater to put on the initial electrodes
Mounting fixtures to get the crystal into the holder
Cement curing (generally vacuum based) gear
Plate to frequency gear

That’s a short list, there actually is a bit more on a full list. The 
cleaning gear can get pretty extensive depending on the end application.


> On Mar 13, 2017, at 3:56 PM, Attila Kinali <attila at kinali.ch> wrote:
> On Mon, 13 Mar 2017 15:01:39 +0000
> Adrian Godwin <artgodwin at gmail.com> wrote:
>> What minimal equipment would you need to make your own crystals ?
> The equipment is quite minimal:
> * A diamond precision saw to cut the crystals
> * Some tool to check the accuracy of the cut (orientation and thicknes)
> * a lapping/grinding machine
> * an electroplating machine (usually sputtering) for the electrodes.
> * either some machine to produce the crystal holder yourself or buy them
> * vacuum system to evacuate the crystal holder and to bake everything
> * something to (cold) weld the case close
> All of this can be put in a (relatively) small workshop.
> The difficulty is also not producing quartz crystals
> in holders. The difficulty controlling the whole process
> to such an degree that you get high quality crystals
> at the frequency you want.
> If you managed to do that, you can further improve
> your system by using a BVA[1,2] like geometry, where
> the electrodes are not on the resonator itself but
> on the surrounding crystal, which acts at the same
> time as holder.
> But be warned, many attempted to re-create the BVAs
> but few succeeded... and none but Oscilloquartz ever
> managed to produce a economically viable product.
> Attila Kinali
> [1] http://www.nature.com/articles/srep02132/figures/1
> [2] http://www.nature.com/articles/srep02132/figures/2
> -- 
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>                 -- Miss Matheson, The Diamond Age, Neil Stephenson
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