[time-nuts] Jackson Labs Fury & Isotemp OCXO134-10

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sun Nov 2 07:58:49 UTC 2008


Matt Osborn wrote:
> I think that I've managed to keep a low profile here, trusting that I
> would learn more if I refrained from random interjections of
> ill-informed thoughts.  However, there comes a point in every man's
> life...
>
> A year or two ago, I took advantage of Said's offer and purchased one
> of the Jackson Labs OEM external OCXO Fury units and am attempting to
> put it to work. I've decided to use an Isotemp OCXO134-10 oscillator
> and have several decisions which I would like to vet with those of you
> that have been down this road before.
>
> The Isotemp unit has an EFC range of 0 to 8 Volts; the Fury has an EFC
> range of 0 to 5 volts.  Using my HP 53131A, I'm able to adjust the
> Isotemp to 10 MHz +- 5 mHz with an EFC voltage of 4.64 volts. That is
> within the adjustment range of the Fury, but I'm not sure of the
> accuracy of the HP53131A.  Should I construct a resistive network ala
> Brooks Shera to 'boost' the EFC range just in case or would I be
> better off just using the Fury 'as is'?
>
>   
If you use a non inverting buffer amplifier with a gain of 1.6 you will
increase the allowance for OCXO aging, otherwise you are a little close
to the Fury EFC output limit of 5V.
Have you tried connecting the OCXO to the Fury and seen how close to the
limit the OCXO EFC is when lock is achieved?
> Secondly, the Jackson Labs advises that since the Fury uses the
> external oscillator as its clock, that the oscillator should be
> powered up before the Fury itself.  I was hoping that I would be able
> to use a single power switch to power both the oscillator and the Fury
> simultaneously, but now I'm not so sure.
>
>   
You still can if you use a suitable delay circuit.
> Finally, are there any of you that have used the Isotemp OXCO134-10
> with the Fury?  Have any of you worked out the various SERVO settings
> that the Fury makes available?  I'm interested in the  DAC gain, EFC
> scale, EFC dampening and Phase compensation.
>
> Any and all advice will be gratefully accepted.
>
> -- kc0ukk at msosborn dot com
>
>   
Bruce





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