Blog

2020/early July: Repairment of magnet power supply

A terminal of a magnet power supply was broken because of metal fatigue.

I had repaired and improved it by fixing a piece of copper.

2020/early June: Solution for bad vacuum of dilution fridge

We had to pump outer vacuum can (OVC) to cool down our dilution fridge.

One day, our turbo molecular pump was broken.

The pressure was 4e-3 mbar at the minimum at low temperature.

It was so high pressure that it was impossible to condense the mixture.

It was found that shealing of the OVC was perfect and the magnet emitted gases.

I fabricated a sorb pump by using aluminium foil and activated carbon.

Powders of activated carbon are glued on aluminium foil by Stycast 2850FT +CAT 23LVJ (thermal conductive epoxy resin).

Too much amount of the epoxy resin makes the aluminium foil too hard to bend.

It might be better to use varnish and not to put glue on the area pinched by blocks of copper.

The sorb pump is rounded like a cigar and is fixed on a copper block which I made in an hour.

I'm doubtful that it works or not then.

Later, it was found that it works and the pressure decrease by 3e-6 mbar.

2020/April: Self-made vector network analyzer (VNA)

Because the maximum frequency our VNA is 13.5 GHz, I measured the transmission spectrum by using Power splitter, IQ mixer, microwave source, arbitrary waveform generator and lock-in amplifier.

My made vector network analyzer is more sensitive than the commercial ones but it takes ten times longer measurement time.

You should buy a commercial vector network analyzer.

2020/Mar: Copper plating

I plated copper on a copper-sputtered silicon substrate with a solution which have no special product.

The surface is rough but is good enough to solder.

Selective plating is possible with tape and mask.

2019/Feb/12: Repairment of Lock-in Amplifier; episode 2

I replaced a fan and BNC connector.

It was lucky that SMB and MCX are compatible.

It was made sure that the Lock-in Amplifier works with voltage splitter made by resistances.

Because I had fixed two broken Lock-in Amplifier, I got one.

2018/Oct/25: Repairment of Lock-in Amplifier; episode 1

I replaced a fun of a Lock-in Amplifier