[time-nuts] Home built cesium clocks???

Predrag Dukic stijena at tapko.de
Sun Jun 29 07:04:21 EDT 2008


That is the reason I wanted FE5440A

First of all it is a military device. CBTs are replaced before 
expiring their operating life so that F18 (or any, i don't know the 
details) do not loose communication in mid air.

All of FE5440a ebay tubes still have some cesium left.  Then, early 
models have their primary loop without any sinthesizor: 14.59+ MHz 
OCXO multiplied by 630.

The simplest possible frequency plan. Synthesizing useful output 
frequency comes in the secondary loop.

Since I do have experience with FPGAs  it is an easy part for me.

Microwave PCB is a bit more difficult, but doable. I do not expect 
too much trouble.

I was in London last november, but the main interest for my daughter 
was Natural History Museum.....  For an 11yr old  it is understandible.

Don't know when I'll make another visit. It is terribly expensive town.

Last week I actually spent to "get something to work"

FE5440a came from ebay not working with some pieces burnt and 
missing.  Also I paid it too much (2500 USD).

I saw some HP's going for 600, but since I already had 6 FE5440a tubes......

But now it is all working, and I learned a lot in the process, so I 
do not consider that effort a waste.


At 12:22 29.6.2008, you wrote:
>In message < at tapko.de>, Predrag Dukic writes:
> >
> >
> >Bruce,
> >
> >I did my homework and collected everything from the internet I could
> >get.  I have this one too.
> >
> >If I go optical way, I still need 9+GHz  electrical source, so I will
> >first recreate electronics. Using off the shelf DDS chips, or using FPGA.
>I would probably start out trying to get the thing to work, then
>optimize later.  For instance, I would start with an off-eBay HP
>synthesizer, rather than fight with GHz frequency PCB layout.
> >No doubt, I will have a lot of fun with the project.
>Ohh, absolutely.
>Have you visited the Science Museum in London ?  They have the original
>Cesium beam frequency standard, spending a couple of hours with that
>would probably help you determine what/where the really hard bits are.
>Also, consider paying PTB a visit, they can probably be persuaded give
>your a tour of their designs.
>Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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