[time-nuts] Super stable BVA Quartz resonators... BVA??

[Magnus Danielson]

From: Bernd T-Online <BNeubig at t-online.de>
Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA??
Date: Sat, 08 Dec 2007 09:27:28 +0100
Message-ID: <475A5570.2010005 at t-online.de>

> Hal Murray wrote:
>   > Why is the top domed?  I assume flat would be easier to manufacture.
> > Why is it not symmetrical?  If the top is domed, why not the bottom too?
> For a plano-parallel qaurtz resonator the diameter must be at least 60 
> times larger than the thickness, otherwise the vibration amplitude would 
> be too high at the edges, and the suspension would damp teh vibration 
> hence the Q would be lowered. For a 10 MHz 3rd overtone SC-cut you would 
> need a crystal of 40 to 50 mm diameter!
> By making a convex contour, the vibration is trapped in the center of 
> the plate, and therefore the Q keeps high (and other parameters improve 
> also).
> Bi-convex contours are more difficult to manufacture, as it is required 
> that the symmetry axis of the upper and lower contour must coincide. 
> Also other parameters become worse. For the BVA the manufacturability 
> would also be much worse as it already is.

While I higly enjoy reading this thread and learning things as I read on, I
notice that several fellow time-nuts have designer skills at advanced SC-level
OCXOs. For those of you, what reading material is there to get better into
depths with these issues? The only sufficiently indepth book I have is Gerber,
Ballato "Precision Frequency Control, Volume 1; Acoustic Resonators and
Filters" (I also got Volume II).

Cheers,
Magnus