free_electron wrote "Get a used Agilent 7000 series".
This can not be MSO/DSO705xB, 710xB: 4 GSa/sec half channel*, 2 GSa/sec each channel
Memory depth 2 channels/4 channels
Standard 8 Mpts/4 Mpts
yup. those. they have 4 a/d converters running at 2Gs/s . in 2 channel mode they interleave two converters to get double rate. I personally use a 7104 as my daily workhorse. It is very responsive , has a large screen ,works with most of the infiniium active probes , has protocol decoders , sufficient memory and fast update rate. It does not need to boot from a harddisk or run some operating system that gets in the way and slows down the machine (like lecroy and RS)
( it does , it runs vxworks , but boots from flash in a few seconds and you don't know there is an OS running. It follows good ol Agilent philosophy : do things in hardware)
This is different from having only 2 converters and interleaving channels. Those kind of machines (can) lie to you ( like the TDS5xx series from tek ) as they sample one channel , then on the next trigger sample the other. so what you see on the screen is taken from two different time origins ! this only works on repetitive signals. and you can forget about catching glitches...
in old analog scopes you could run in alt or chop mode but many of the early generation digital scopes ran in alt mode only. And that is VERY dangerous as the time correlation is lost.