[time-nuts] MTI 260-0624-D OCXO

[timenut at metachaos.net]

Bob,

In this case, I know how it was taken off the board - it wasn't. They just cut
the board around it. I had to remove it myself. Nice thing about that, is that
I got a nice plastic, pre-formed part that fits between the board and the
OCXO, probably as an insulator.

You are also right about the number of things that you need to test to make
sure that one of these is fully functional. However, this is a "starter" OCXO
for me and I don't yet have the equipment to perform the tests. The best that
I can do is to make sure that, when powered up

   1. I see something that sort of looks like a sine wave at a reasonable
      magnitude.

   2. My 2465B CT frequency counter thinks that it is somewhere near 5Mhz.

   3. If I apply gnd, or VRef to the adjustment pin I see the frequency change
      at least a small amount.

Without more equipment, there isn't much more that I can do to test. Unless
you have some suggestions?


Mike


> Hi

> Best guess is these things get taken off the board with either a big torch or a charcoal fire.
> You can ask Mr Google to dig up pictures of the process. Depending on just how quick
> they are, the insides of the OCXO can easily be reflowed. The likelihood of it reflowing and
> cooling back to a reliable joint … not real good. 

> Bob

>> On Feb 17, 2016, at 5:16 AM, Andrea Baldoni <erm1eaae7 at ermione.com> wrote:
>> 
>> On Tue, Feb 16, 2016 at 07:58:21PM -0500, timenut at metachaos.net wrote:
>> 
>>> I just received a 5Mhz OCXO from eBay (MTI 260-0624-D OCXO). After testing it,
>>> it is clear that it is defective.
>>> 
>>>   1. It never heats up.
>>>   2. The reference voltage is zero.
>>>   3. Only noise is seen on the output pin.
>> 
>> I had the same issue with some of them. It's very likely that the internal
>> solder connections from pins to PCB are broken, at least, the one for power.
>> It happens because the inner oven is heavy and there isn't any thermal
>> insulator (besides air) to keep it from moving.
>> 
>> Wheter the crystal has been damaged or not, it's unknown. I had one where the
>> crystal actually fell off from its supports too.
>> 
>> I posted a link to photos of the internals, time ago. The link is dead now
>> and I don't think to have the photos anymore but perhaps someone downloaded
>> them.
>> 
>> Best regards,
>> Andrea Baldoni
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-- 
Best regards,
 Timenut                            mailto:timenut at metachaos.net