[time-nuts] FE-5680A Mechanical Question
Mark Spencer
mspencer12345 at yahoo.ca
Thu Jan 12 22:01:34 UTC 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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