[time-nuts] FE-5680A tear down on Youtube

[paul swed]

Well as interesting as that might be the sites blacked out. Some protest.

On Wed, Jan 18, 2012 at 11:38 AM, Bob Smither <smither at c-c-i.com> wrote:

> Attila Kinali wrote:
> > On Fri, 13 Jan 2012 12:50:19 -0500
> > "Bob Camp" <lists at rtty.us> wrote:
> >
> >> The gizmo on top of the crystal is a rapid transition thermistor. The
> >> Russians came up with them for use in OCXO's back in the 1970's. It's
> there
> >> to heat the VCXO crystal, sort of an OCXO.
> >
> > Do you have any references to this? I couldn't find anything on the net.
> >
> >                               Attila Kinali
>
> From http://wb9ipa.qrpradio.com/60meter/osc_filter/osc_filter.htm :
>
> "PTC thermistors exhibit a unique behaviour, in that their resistance
> increases
> as the temperature increases.  This temperature to resistance relationship
> is
> very non-linear; in fact, the change becomes very rapid above a temperature
> known as the Transition Temperature.  This property can be exploited to
> make a
> very simple, self-regulating heater."
>
> See also http://c-c-i.com/node/165 for an application note that has a
> pretty
> good discussion of this.
>
> --
> Bob Smither, PhD                                   Circuit Concepts, Inc.
> =========================================================================
>   Friendly relations with all nations, entangling alliances with none.
>     --Thomas Jefferson
> =========================================================================
> Smither at C-C-I.Com  http://www.C-C-I.Com  281-331-2744(office)  -4616(fax)
>
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