At one time in my life, I designed RF equipment for a living. Of all the tools I got to work with, the one I liked the most was the spectrum analyzer. In my personal life I am a ham radio operator; although I am not very active, from time to time I do like to build transmitters and amps. So as soon as I played with a spectrum analyzer at work, I knew I had to have one.
The problem with buying an RF spectrum analyzer is that they are expensive - I mean like the  cost of a new car expensive. So I had to look into alternatives, and I found some designs to do it yourself. I settled on a kit that you can find here, which consists of a few boards that you have to assemble and wire up. You include your own box, controls wires, and connectors and you're ready to go. The design inputs an RF signal up to about 500 MHz but you can buy other parts to enable it to go to about 2 GHz.
The output goes to an oscilloscope, but is in the audio range. It is possible to input it into a sound card on a computer for viewing on a pc. The kit is the typical type, complete with boards and components that you have to solder on. The hard part was fitting the analyzer into a box and making it all work. I opted to put it in as small a box as I could, which was a little difficult but has worked.
I have utilized this spectrum analyzer a number of times and found it to be quite reasonable if you just need to see the harmonics or bandwidth from a transmitter. It's also great if you want to see all the signals in the band with just a glance. For the most part it sits on the shelf, but it's a great instrument when you need it. I have considered future enhancements to the design to make it all computer controlled, but so far the need hasn't arisen.
| 
Re: Build an RF Spectrum Analyzer
