To Greg T,
An SDR is basically an all-band receive radio (converter) capable of listening to anything from DC to whatever the limit of your SDR converter is, on whatever software program you want to use. It can and has been used as a spectrum analyzer by many. The better the antenna being used the better the signal, your small antenna would not last long before you decided to connect to your big antenna, but to monitor yourself anything would work. The main thing to remember is that you can not connect a "T" between the antenna to the radio and the SDR converter.....you would kill the SDR with RF from the radio. A switch box between the antenna to the radio or SDR is fine, but MFJ sells an adapter to do that automatically, and have heard that they have their problems.
My SDR converter of choice came from DX-Patrol (back in 2015) still going strong and always on, it was their first unit and they have since updated it. The connection to the computer is a USB cable. Of course, they use drivers, and it's either all explained with your converter of choice or online. Youtube has many videos, many of which have the SDR connected to the inside of the ham radio, but that is not what you want.
I use it on a Windows10 computer, depending on the SDR program you want to use, I use HDSDR. Like any other program, they update all the time adding more options. They have more options than you can even think of using. You have to remember it's all in the software you use, the converter is the receiver adapter that connects to the USB port on the computer.
The program that you choose to run (and there are many) would have digital filters that let you adjust your receive in many ways, and a Zoom feature to let you expand your frequency range (2Mhz plus range). You could sit and monitor from 26.000 to 28.000 to see where the action is, provided you had a good antenna connected to the converter, or you could Zoom in to just the span of a few Kc, which is very small (don't think you would ever go that small).
One other feature is "Record", if you record anything and you had Zoom wide open, you could go back and play it. What you could listen to is whatever is shown on the playback (mine are wav. files), if people were on 27.025 and you were recording on the action 27.385, you would be able to listen to what was said on 27.025 or anyplace else that was on your recording just as if it were "Live".
If you just wanted to monitor yourself that's fine, but you soon get tired of that and start listening to all the other action that your radio can't see. Great for late at night when there is no one on the air, and someone keys down, that little blip is shown on your screen, but the Zoom has to be set wide enough to catch them, even if they are on the free bands.
Do your research on the subject, I'm sure there are others here that have done it and how they did it.
You can start here if you want:
https://www.nooelec.com/store/nesdr-smart-xtr-hf-bundle.html
All the antennas included may never get used by you, but it is a good price.
I could go on and on, but you would never regret getting an SDR setup...
73