[time-nuts] FE-30 OCXO

EWKehren at aol.com EWKehren at aol.com
Sat Dec 5 12:57:46 UTC 2009


I have opened quite a few soldered cans using a torch. Max heat for a very  
short time did the trick. Any exposed connectors have to be protected. I 
use  Alum. foil. I have never had any sign of heat on the internal guts.    
Bert Kehren Miami
 
 
In a message dated 12/5/2009 6:06:56 A.M. Eastern Standard Time,  
rexa at sonic.net writes:

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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