[time-nuts] 10MHz Rubidium reference source for frequency counter

Alexander Pummer alexpcs at ieee.org
Wed Oct 29 17:57:17 EDT 2014

Don't give up Karen, the Morion oxcos are relative easy to repair, you 
need one coca-cola can, cut it is pieces until you get a very thin ALU 
foil, get some thicker carton wind around the box of the OXCO's box that 
way you have a heat isolation between the OXCO's box and the vise, which 
you need to hold it, but hold the OXCO that way, that the bottom part 
where the soldering is fare away from the vise, and the can is upside 
down, "fire up" a relative large  [ min. 100W] solder iron, if it has 
temperature setting set to the maximum  and if it is hot push it hard 
against  the OXCO can, as soon as the solder melted push a piece Alu 
foil into the gap [ there is a gap between the bottom of the can and the 
rst of the can ] and move to the next part to melt the solder. You need 
to push in at least 5mm long the Alu foil into the gap, if you get it 
all around, you could pull out the content of the OXCO can.
That is a double oven oscillator, depend what is the problem , you may 
have to open the internal can also, usually it is "visible" if something 
is broken, just power up and follow the current paths, with meter and 
scope probe, it is practical to temporarily disconnect the oven heating 
[ the large heater transistor ].
I fixed five of them, you need some patience and luck and you have to be 
very careful.

On 10/29/2014 11:09 AM, Karen Tadevosyan wrote:
> Charles,
> Thanks a lot for the detailed explanation and recipes. Understood and will check this weekend.
> All my Morion 10MHz MV89A OCXOs are used and from eBay's. That's why the first version of broken surplus MV89A looks realistic.
> Best regards,
> Karen

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