29 May
2008
29 May
'08
2:47 p.m.
David,
I agree with whomever wrote about sticking with Tek analog scopes. If you
want your squarewaves to look square though you need a bandwidth 10 times
the signal of interest ( i.e. 20 MHz squarewave 200 MHz scope ). The more
odd harmonics you can push through the more " square " it will be, and you
would like to pass the 3rd, 5th, 7th and 9th harmonics if possible. I still
like my OLD Tek ( 5000 BTU, Ethan could use this in the South Pole ) 535A
with CA plug-in for most old vintage stuff. The display is still as crisp
and bright as the day I bought it ( used at a salvage sale ). I have a high
dollar Tek digital LCD scope but was very disappointed to find out the 2 GS
/ second front end is only 8 bits wide !! I only use it if I need a
hardcopy for a customer of some signal or to capture a signal that only
happens once. The signal displayed is only as " crisp " as the dots in the
LCD are small. Good luck in your search. Now, if you could find an HP
LogicDart cheap somewhere ......?
Best regards, Steven
Gerhard wrote about a 100 MHz oscilliscope:
For slow signals usually present in classical
hardware, thats no
problem.
That's true.
Many people have the mistaken belief that a 'scope with 20 MHz bandwidth
is adequate for looking at 20 MHz digital signals, but that is not true.
For digital signals you usually want bandwidth of at least five times the
peak frequency of the system, and preferably more. It's hard to
diagnose problems when fairly square edges on signals look like
sine waves on the 'scope.
Eric