[time-nuts] OSA 8600 Oscillators
cfmd at bredband.net
Wed Mar 15 17:31:42 EST 2006
From: "Rick Karlquist" <richard at karlquist.com>
Subject: Re: [time-nuts] OSA 8600 Oscillators
Date: Wed, 15 Mar 2006 14:19:39 -0800 (PST)
Message-ID: <18518.104.22.168.225.1142461179.squirrel at webmail.sonic.net>
> >> The PDF says that nothing contacts the crystal, which implies capacitive
> >> coupling. Interesting.
> > This is the core idea of the BVA technology as I have gathered it. By not
> > putting aluminium contacts on the crystal, there is no Al atoms/ions
> > migrating
> > into the crystal and thus causing aging. Instead is the connectors really
> > close
> > by since their presense is to cause a electrostatic field anyway.
> My impression talking to the experts about this is that atoms
> migrating into the crystal is not one of the main causes of aging,
> and thus this is a solution to a non-problem. There are many new
> problems created by the means necessary to do non contact electrodes.
> Thus, the BVA design should not be seen as a panacea. They may
> be very good crystals or not, but the fact that they are BVA is
> no guarantee of anything in particular. Not to mention that fact
> that you still have the electronics and oven to worry about, which
> the BVA structure has no effect on.
Indeed. The whole electrode arrangement is meaningless unless you do a whole
bunch of other things too. The thing is, I suspect they do care about those
details since the BVAs doesn't come very cheap, small or power-efficient.
There is no silver bullet. Temperature gradients, suspention, oscillator
design etc. etc.
Notice also that they specify 30, 60 and even 90 days of continous operation
before reaching full spec. This is temperature shift aging in operation.
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