[time-nuts] FE-30 OCXO

[Rex]

I had a Knights 10 MHz OCXO that I really liked for my ham stuff, 
partially because it was clean and stable, partially because it worked 
on 12 V making it great for mobile radio use.

Quite a few years back I messed up and hooked up the battery supply 
backwards which killed it. I liked it enough that I opened it up, 
replaced a bunch of semiconductors and fixed it. The circuits had 
surface mount parts, so I guess it was late 80's or early 90's vintage.

It was a standard large metal can format, about 2 x 2 x 4 inches, 
soldered together on the connector end.

Trying to break the solder seal would have been a lot of work. I'm sure 
the solder flowed at least 1/8 inch down into the groove between the end 
piece and the can. I have a milling machine and I used it to cut a slot 
around the outside of the can. The deepest edge location of this cut was 
about 0.225 inch down from the end edge of the can. I can't remember 
exactly how I decided where to make this cut, I probably made a test cut 
in one spot. What I did was cut beyond the solder joint and just deep 
enough to go through the outside can, but there was still overlap 
between the inner end piece and the can so it was not too difficult to 
reassemble after fixing the electronics. I think I tack soldered the 
pieces back together and then sealed it with silicon. Finally I wrapped 
the outside with foil tape to electrically seal the slot.

If I didn't have the milling machine and slotting saw, I think I would 
try my method with a dremel tool by hand before I would try to unsolder, 
either mechanically or with heat.

For perspective, I had earlier tried to unsolder a smaller tcxo can. I 
used a propane torch with a gentile flame. By the time I got the solder 
melted and managed to separate the two halves, I had also desoldered a 
number of random devices from the internal circuit board. Unsoldering a 
can without overheating the contents is not easy.

So, one more approach for your project.



Joseph Gray wrote:
> That's a good idea. I just spent the better part of the past hour
> trying it. So far, I have made a nice pile of solder shavings and have
> cramped my hand. I haven't succeeded in opening the OCXO, however. The
> base fits very snug into the can, so there isn't much more I can dig
> out. I'll make another attempt tomorrow, after my hand recovers.
>
> Joe
>
> On Fri, Dec 4, 2009 at 8:46 PM, Ed Palmer <ed_palmer at sasktel.net> wrote:
>   
>> I recently had good luck opening up a soldered oscillator with a utility
>> knife.  Rather than use the sharp edge, I used the back edge of the blade.
>>  That way, instead of trying to push the solder aside, the blade actually
>> digs it out of the crack - sort of the way a cutter works in a metal lathe.
>>
>> Of course, great care is required to ensure that you don't amputate
>> something!
>>
>> Ed
>>
>>     



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