I have always like to face intellectual challenges. Given an interesting problem, I would often pursue it for days before dropping it from my mind, just to pick it back up a few days later. Rarely do I give up on a problem, because once I do and get the answer, in a sense I have not learned anything. To be more precise, what I have gained in knowledge, I have lost in understanding. In this blog and upcoming one, I would like to discuss a particular group of challenges I have faced in the lab, which are all challenges dealing with uncertainty.

When I walked into Professor Ben Mazin’s Lab, I thought that I would not need to ask for help from my mentor. Seeing as my project was to build a analog readout, which for the most part seemed self-contained, it seemed, at least at the time, perfectly reasonable. I thought that I could, for the most part, use logic to figure out what I needed to do.

Needless to say, that ideal was wrong. In fact, for one entire week, my mentor and I could not figure out how a certain piece of equipment(an IQ demodulation device to be exact) would not work, just to find out the reason was because one little jumper(removable component of a circuit that acts like a switch) need to be removed.

Problem

Solution

Now, here is my excuse for such a blatant error. The instructions for what these jumpers do are in the “Advanced RF Testing” section of the manual. Seeing as my “Basic RF Testing” was unsuccessful, I made the seemingly logical choice and did not read that particular section.

What my mentor and I did instead was go through a series of “tests” in an attempt to isolate the problem.

First, we thought that perhaps the signal was being sent to some other port on the IQ mixer. So, we hooked up all the ouput ports to an oscilloscope, hoping that one signal would give a sinusoidal waveform. That didn’t work.

Next, we decided to upgrade our testing device from a oscilloscope to a frequency analyzer. Our thinking was that the oscilloscope was too insensitive to the signal that was being read out. In essence, we decided to upgrade the equipment. This also didn’t work.

Then, we tried to measure current and resistances on various parts of the IQ mixer to see if a component was broken. Everything seemed ok.

After a few other things that my mentor tried to do also failed, he told me that we should read the manual from front to back and see if it tells us anything. The next day, he found the “Advanced RF Testing” section, and making the adjustment shown in the pictures above, we finally got the IQ mixers to work.

The immediate thing I learned from this is that knowing which parts of the maual are relvant for my task is a good skill to have. I read most of the manual, and none of it helped for our problem, and in some cases, (because I am a physics major and not an electrical engineering major), confused me. But, wanting to turn this into a learning experience for me, in my next blog I will talk about how to deal with situations like this if they arise again.