[time-nuts] Mystery hp Ovens For Sale

[Bob Camp]

Hi

The “small” (less than a pound) 100 KHz crystals are not really great 
in terms of performance. If you get a GT (big thin square plate with attach 
right in the middle) they can have ok temperature performance. Because of 
their small size, their Q is relatively low and thus things like phase noise and
ADEV are not very good. 

Not accurate, but at least a hand waving sort of number:

If a high Q 5 MHz is 0.5” diameter *and* you did the same design at 
100 KHz, it’s going to be 25” in diameter. (Obviously not the way to do it). 

Bob

> On Jun 4, 2016, at 12:59 AM, Ian Stirling <is at opus131.com> wrote:
> 
>  It looks like the quartz is in the sealed glass "valve", or "tube".
> 
>  I have removed a similar glass vacuum enclosed 100 kHz frequency
> marker generator from my Eddystone EA12 receiver that I bought from
> Tom Roberts, G3YTO (SK 1985), in September 1978. I don't use the EA12
> any more and I wonder what kind of timing device I can make from this
> beautiful slab of quartz, approximately 28 x 5 x 2 mm. I don't have a
> data sheet for it, but I can see which pins are connected to the quartz.
> In the receiver, it has a spring stabilized black metal cover that mates
> to the socket. I suspect that is so that the thirteen valves and their
> heaters create a thermal equilibrium and the black shroud lets the
> crystal bathe in it. I ran the EA12 24/7 from then until I bought and
> used an IC-735 in January 1987.
> 
> It is a GEC Crystal Unit, 100 kHz, serial number 82690 and type JCF/193,
> "Made in England", and it looks like it means business.
> 
> Ian, G4ICV, AB2GR
> --
> 
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