[time-nuts] Opening an Isotemp OCXO

Bob Stewart bob at evoria.net
Fri Oct 28 16:09:14 EDT 2016

Hi Bob,
Can't the OCXOs be characterized pretty closely by someone with the right tools and staff?  I don't have a big sample to speak from, but the Trimbles I use only have a couple of ceramic coated pieces, and those can be exposed down to the die by hand and then characterized, can't they?  Granted, that's beyond my capabilities, but given the right tools and employees...


      From: Bob Camp <kb8tq at n1k.org>
 To: peter at reilley.com; Discussion of precise time and frequency measurement <time-nuts at febo.com> 
 Sent: Friday, October 28, 2016 2:46 PM
 Subject: Re: [time-nuts] Opening an Isotemp OCXO

Roughly 99.9% of all OCXO’s made go to large OEM customers. The percentage may
actually be a bit higher than that. There are relatively few markets that “catalog” OCXO’s 
sell into.

Inevitably the first thing that an OEM wants is some form of customization. A specific 
supply voltage, a certain output format, a wider (or narrower) EFC range … there
are lots of possibilities. For every OCXO that goes into production for these guys, 
five or ten other designs are done (all equally custom) that never see the light of day
past the samples.

The spec’s that these parts are built to are negotiated between the supplier and the OEM.
In some cases they are the property of the OEM and the spec is their control drawing on
the part. In other cases the drawing is done by the supplier for that OEM and is property
of the supplier. 

The OEM often has competitors. They would *love* to get access to the OEM’s control
drawings to see how the systems are designed. The supplier has competitors. They
would love to get access to the suppliers drawings so they can make cheap knock off
parts to those drawings. In both cases, the drawings (in general) have very real value. 

The net result of this is that both suppliers and OEM’s put fairly fancy rules in place about
passing out drawings. More or less anything up to and including being boiled in oil is
(if legal in the jurisdiction) fair recourse under most of these rules. Needless to say
people learn pretty quick that you get fired for this sort of thing. 

The net result is that the drawings for most OCXO’s simply do not exist in the public
domain. They do (or did) exist in some form somewhere. Getting at public copies of 
them is highly unlikely. Going by “similar looking” drawings is not a real good idea ….



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