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

[Jim Hall]

Regarding your second question concerning power supply sequencing.  How 
about using one of the "Power Supply Sequencer" chips (e.g. MAX6819)).  The 
output of your power supply would go directly to the external OCXO, the 
Power Supply Sequencer chip and the input to a MOSFET switch.  Output of the 
MOSFET switch goes to the Fury.

When the power supply is switched on the following sequence occurs (assuming 
a MAX6819):
1) Power is applied to the OCXO,  MAX6819 and MOSFET switch input
2) The MAX6819 starts a 200 millisecond delay
3) After 200 milliseconds the MAX6819 turns the MOSFET switch On, powering 
the Fury On

MOSFET switches can be used that have only a few tenths (or less) of an ohm 
of "ON" resistance.  This minimizes degradation in voltage regulation of the 
power applied to the Fury.

The MAX6819 data sheet gives useful examples applicable to the above 
application.

73,

Jim Hall W4TVI



--------------------------------------------------
From: "Matt Osborn" <kc0ukk at msosborn.com>
Sent: Saturday, November 01, 2008 11:28 PM
To: "time-nuts" <time-nuts at febo.com>
Subject: [time-nuts] Jackson Labs Fury & Isotemp OCXO134-10

> 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'?
>
> 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.
>
> 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
>
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