$20 for a Pro-2021 in mint condition is a GREAT deal. I had one of those back in the 80's when it was in production. IIRC, it went for $200 or more when new.
It is well made...built like a brick [censored] house! Just plug it in and leave it on 24/7 and it will last practically forever. It is definitely built to last.
RF performance was good and audio output and quality was excellent. I wished mine would scan faster than 8 channels/sec but it was ok for monitoring a dozen or so frequencies.
My only real complaint with it is typical of RadioShack scanners made by GRE....they have WAY TOO MUCH squelch hysteresis. I developed a fix for it like others have done. The hysteresis feedback in the squelch circuit is provided through a resistor connected between pins 12 and 14 of the FM IF chip (Motorola MC3357 or equivalent). The resistor value needs to be increased to something like 100k ohms. The original value is somewhere between 27k and 47k ohms. You could also remove the resistor and you'll have no hysteresis at all but the squelch will chatter, sputter, or crackle at the threshold. Having at least SOME hysteresis will help keep it stable at the threshold. I like to have just enough to keep it stable at the threshold and no more. Any more than that is too much and gets in the way. If you dig into this circuit, you'll want to experiment with the resistor value to get the type of squelch circuit behavior you like.
If you're not up to modding your radios, then don't attempt the above mod. Leave well enough alone. My modding the squelch circuit was done to suit my personal preferences, not to fix a problem.
You got a good deal and a good scanner!
