From: Bernd T-Online <[EMAIL PROTECTED]> Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Date: Sat, 08 Dec 2007 09:27:28 +0100 Message-ID: <[EMAIL PROTECTED]>
> 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 _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.