Saturday, April 30, 2016

10MHz OCXO Teardown (NDK ENE3311A)

Here we go with another OCXO teardown. This time we are taking apart an NDK ENE3311A 10MHz OCXO. This is a little 1" square unit with a square wave output. You can find them on eBay for about $15 USD.

I have a bunch of these on hand, so I don't mind sacrificing one
to learn more about the internal construction.

I cut around the bottom of the can with a dremel.
It eventually came off with little drama.

Not a lot going on inside this unit, eh? Just like in the CTS OCXO,
the oscillator circuit is on the top of the PCB, and the crystal is
bonded to the bottom side.

Close-up view of the top of the PCB, along with annotations of the pinout.

I cut the pins and flipped the board over. Ok! This side is much more interesting.
The little IC in the upper right is the output buffer. One of the SOT-23s on the
left is a voltage regulator. The remaining IC is probably an opamp.

There's a thermal pad and some white goop bonding the crystal to the heater elements.

I scraped away most of the thermal compound and lifted up the crystal.
We have two power devices and two resistors acting as heaters, just as expected.

That's all for this teardown! I might reverse-engineer the schematic for this one as I did with the CTS 1960017 OCXO. However, it's pretty easy to see what is going on inside this unit. Besides getting exact part values and device IDs, there is probably not a lot to be gained. What are your thoughts on the internal construction of the NDK ENE3311A OCXO?

Thanks for reading!

- Dan W.

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