[time-nuts] MTI 260-0624-D OCXO
kb8tq at n1k.org
Thu Feb 18 07:09:12 EST 2016
It is *much* better to have an OCXO that you do not need to test to death.
There is simply to much testing to do. A modern factory does not test the
quality into the product (of any sort) they design in and build it in. The same
is true of the normal customer for virtually any component. They make sure
the parts come from somebody they can trust and save a lot of testing time.
That said, yes, I have a pile of scrap parts sitting in front of me as I type this.
It’s a hobby. Time does not count. It lets me play with all sorts of toys doing
the testing. I occasionally learn things in the process. Mostly I learn that
my hope of a 100% perfect batch is still a dream ….
> On Feb 17, 2016, at 9:56 PM, timenut at metachaos.net wrote:
> 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
> 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?
>> 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.
>>> 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
>>> Best regards,
>>> Andrea Baldoni
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> Best regards,
> Timenut mailto:timenut at metachaos.net
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