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

[Bruce Griffiths]

Hal Murray wrote:
> BNeubig at t-online.de said:
>
>   
>> The key points which yield the BVA's improved aging are, that - the
>> whole resonator package is made from quartz, consisting of the
>> resonationg quartz plate in the middle section and the two mounting &
>> sealing plaates on top and bottem - you may call it a Hamburger style
>> ;-) - the resonating plate is held through quartz bridges rather than
>> metal  suspensions, thus reducing mounting stress.
>>     
>
> Neat.  Thanks.
>
> 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?
>
>
>
>   
One surface is convex to facilitate suppression of unwanted harmonics.
Its actually quicker and easier to make a planoconvex "lens" than a
biconvex one.

Bruce