Miniature filters II

I talked a little while ago about a prototype miniature low temperature LCR filter I made. Well I’m making the real things now, so I thought I’d share the process as they come together. Here is the first stage: The metalwork. This doesn’t actually take very long.


Each filter needs a base plate (top metal pieces with the crosses etched in) to secure the filter and provide the cryostat ground – which I’ll write about in a separate post, a flexible printed circuit board (the flat middle strips of Copper), a supporting wall with feedthrough holes (those ones are pretty obvious) and a lid (bottom metal pieces).

The walls are made just by bending the relatively thin copper plate around 4 times. The holes are made with a metal punch and are 3.18mm in diameter.

Let the mass production commence!! Well, I’m making 5 of these. I think I’ll need 4, and you always make a spare 🙂 I’m thinking of mounting them on the new fridge at 4.2K, 1.5K, 50mK and base temperature, but I haven’t quite decided yet.

Timewise this took a couple of hours (whilst I was waiting for the fridge dewar OVC to pump down – gotta love critical path analysis).

Here is a slightly more artsey photo of the same thing:



2 thoughts on “Miniature filters II

  1. supradeep says:

    Are you trying to build a new probe ? What are your planned future experiments?

  2. physicsandcake says:

    Hi! Yes, I’m doing the wiring on our new dilution refrigerator. We will hopefully be doing quantum coherence and microwave activation experiments on qubit structures. (Rabi oscillations and Spin Echo type experiments)

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