[time-nuts] FE-5680A Mechanical Question

Mark Spencer mspencer12345 at yahoo.ca
Thu Jan 12 17:01:34 EST 2012


That re trace result is impressive.   

Thanks for sharing that.   Looking forwards to getting my hands on one.



Sent from my iPod

On 2012-01-12, at 3:04 PM, EWKehren at aol.com wrote:

> I hear all these ideas from paper tigers. How about building something and  
> report on it. I can do a Shera for $ 40 and add a $ 20 GPS.  And it works. 
> I did fail to mention that I also have retrace data. Over the test period I 
> had at least 10 power outages from seconds to a couple of hours. The Rb 
> goes  right back to 1 E-12. It would be nice if some one independent does a 
> test on  aging, maybe I was lucky and got a particularly good unit.
> Bert Kehren
> 
> 
> In a message dated 1/12/2012 12:04:03 P.M. Eastern Standard Time,  
> albertson.chris at gmail.com writes:
> 
> I plan  to lock my FE5380 to a GPS also.  But I want to mine to  "unplug
> able".   The idea is to connect the GPS and let it sync  for some
> period of time.  Perhaps hours or maybe weeks, the longer the  better
> and then you can disconnect the GPS and the FE5680 free runs at  that
> frequency.   Plug it back in to sync it.
> 
> I think it's  clear that a small micro processor is required or a
> desktop computer could  be used.  The FE5680 uses the RS232 port for
> frequency adjustment you  are going to need a computer.  I think a Tiny
> AVR would do fine.   It is a $2, 8-pin chip.   It has a 10-bit A/D
> converter to read  the phase offset and you can use another pin for
> serial output to the  FE5680.  If you used a digital phase detector
> you'd not need the  A/D.
> 
> The controller would work like the typical GPSDO controller  except
> the DAC is physically inside the FE5680.  This make it  easier.
> 
> Physically,  It will be mounted inside a steel box about  the size of a
> shoebox (The box once held a pair of large sized disk drives,  from
> back in the days when drives where about 3" thick)  There is a  thick
> aluminum plate the divides the box vertically. the FE5680 sits on  top
> of the plate, a heat sink is bonded to the underside of the  plate.   A
> low speed fan moves air through the box slowly.   The fan is
> controlled by a temperature sensor bonded to the  plate the FE5680 is
> mounted on.   This is a crude type of "oven"  using the FE5680 is a
> heating element.   I hope to   stabilize temperature to about 2C.
> I'll start with a simple comparator chip  as a on/off fan controller
> and eventually use another 8-pin uP to do a full  PID controller with a
> three wire fan
> 
> Chris Albertson
> Redondo  Beach,  California
> 
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