[Elecraft] Oscilloscopes (WAS: spectrogram)

[ab4cz at comcast.net]

Poor John asked if he could use spectrogram as an oscilloscope, and that's morphed into recommendations to buy a 400 MHz scope!  In my last job I was the video amplifier design guy, and in that role I designed video amplifiers to drive CRTs in high-resolution industrial computer displays.  Over the years, resolution requirements constantly increased so the last generations of products had CRT cathode drive requirements on the order of 60Vp-p with <3nSec rise and fall times.  As I recall, the last video amp I did was around 2.7nSec at 60 Volts drive.  (now you know why CRT monitors can cause serious RFI ... shielding was one of the biggest challenges).  My point is, I am familiar with and appreciate the need for fast oscilloscopes when the application requires it .  My favorite was the 475 until we got 2465's, and I really liked the 2465.  But I always felt the 2465 was more fragile than the old 465 - 475 series stuff, and the things that broke in the 2465's were always expensive and proprietary.  If you were going to buy one for home use, it might be easier to keep the older stuff going because they're tougher and fewer of the parts are made of unobtainium.

But .. my REAL point here ... for home use for the average hobby user, we almost never really NEED a 400 MHz or even 250 MHz scope.  My home scope for years was a Tek 455 with 50MHz bandwidth.  I did design development work at home and fixed a zillion things with that scope and rarely found the 50 Mhz bandwidth a problem.  For the less demanding hobbiest, it might NEVER be a problem.  Of course you have to apply judgement and realize the limitations of the instrument, but that's ALWAYS the case with any measurement.  People tend to think they have to always have the highest performance and anything less is inadequate (hence the internet surfers with 3.2GHz Pentium IV computers and a Gig of Ram to send e-mail) but if you hold off buying a scope because you can't afford the 250 MHz or 400 Mhz scope that you THINK you need ... be aware you can do 99% of your oscilloscope work with a decent 50Mhz scope.  If you're designing fast logic or think you need to look at the carrier of a VHF transmitter, you need speed, but for fixin' radios, it's rare.  Because of the "gotta have the fastest" mentality, the old 455's and such are real bargains, and will serve the average hobbiest well.  Any scope is better than no scope.  I can't imagine life without an oscilloscope in my basement.  I have four ... including a 922 (15MHz??) that's my favorite for pick it up and go to help a friend fix something ... 

Just my humble opinion based on some years of experience ...

Jim
AB4CZ