Who ever thought you could get a brand new low cost spectrum analyzer for fifty dollars? Well, you can, and it works fine.

So, most of us had a weird Christmas in 2020. But we were able to at least exchange a few gifts even if the big family gatherings went by the wayside. One of my favorite presents was a low cost spectrum analyzer.

You may recall that I wrote about the TinySA when it was released last summer. At only $50, I could not resist adding one to my Christmas list. And sure enough, my sons responded to my wish. At this price, TinySA has some limitations, but I think you will find it to be a useful addition to your electronics workbench.

TinySA performs mainly up to 350 MHz and, with a few tricks, to 960 MHz. Basically, it is a traditional heterodyne spectrum analyzer using a 433 MHz first IF and an 800 kHz final IF where the scanning and A/D conversion takes place. You can see the circuit block diagram here.

Every spectrum analyzer filters signals down to a resolution bandwidth, which for TinySA ranges from 3 to 640 kHz. RBW effects sweep speed (which can be quite slow on TinySA) and sensitivity, which seems to range from -90 to -102 dBm.

Above, you can see the TinySA output when monitoring local medium wave – 500 kHz to 1.5 MHz on my wideband loop antenna. The spike on the right hand side (1440 kHz) is the second harmonic of a strong local signal on 770 kHz.

Low Cost Spectrum Analyzer – How It’s Done

So, how do we get such an amazing device for such a low cost? Basically, designer Erik Kaashoek simply used a really cheap wireless transceiver module to do most of the heavy lifting. The Silicon Labs Si4430 module contains most of the oscillators and filters running under microcontroller guidance.

My TinySA runs off its battery for a few hours, so it’s very portable. But, as with the NanoVNA, you can use software and a PC for charging, control and capturing display output.

I am sure to find many uses for my TinySA, which also doubles as a signal generator. Just get one and have fun.