Now that I'm back home I'm getting back into the hobby. I'd like to expand my shack setup to include a oscilloscope so that as I tinker on craigslist/yard sale cobras and unidens I could put them on the scope to see how clean they are as well as checking amps as I would like to build more and tinker on yard sale finds as they come Accross my bench. What would be a good fairly cheap used oscilloscope for around $250 or less. I see a bunch on Craig's list and ebay, but don't know which to get. I see some listed as 20mhz and 30 MHz which one would I want if I was solely gonna tinker on older cb equipment. I'm assuming the 20mhz is that correct?