[sdiy] Oscilliscope suggestions?

[Cornutt, David K]

I've been pretty happy with a Tek 464, which is
a 2-channel analog scope with delayed sweep and
storage.  I agree that you absolutely must have
two input channels.  The ability to select chop
or alt mode for displaying of the two chanels is
helpful with slower signals, as is the ability to
select which channel triggers when in these modes.
(Some terminology: Two-input (or more) analog scopes
will usually have two ways of displaying the 
multiple traces with a CRT that produces only one
beam.  In "chop" mode, the beam traces a bit of
one channel, blanks off, then switches to another
channel, displays a bit of that, then blanks and
switches again, etc.  This all happens very fast
so it looks like the scope is producing mutliple
simultaneous traces.  Chop mode is useful for
displaying slow stuff like LFOs and envelopes.
In alt mode, the scope draws the entire trace for
one channel, then switches to another channel and
traces that, etc.  This is better for fast signals.
However, alt mode does cause some complication as
far as selecting the proper trigger.)

The storage mode is somewhat handy for displaying
slow stuff, although with the typical high-persistance
phospor it's not essential.  I do get some use out
of the delayed sweep.  The 464 has external triggering
but I have yet to find a need for it.  One other thing
you probably want: X-Y mode, which is very useful for
tuning and calibrating oscillators and filters.

(Suggestion: Maybe we should make a scope FAQ to
put up somewhere listing what everyone considers
essential in a scope to be used for synth DIY.)

Additional note: Be very, very careful when buying
scopes through Ebay (or any other source where you can't
try out the scope before you buy).  Make absolutely
sure that the seller has a money-back guarantee against
a DOA scope and has good feedback.  Don't rely on
trace pictures in the listings; those can easily be
Photoshopped.  I had a bad experience with a seller
who sold me a DOA scope, refused to refund, and then 
almost went postal when I left him negative feedback.  
(I had to get Ebay security to get him to stop calling 
my house.  The guy kept claiming that he had never
seen the scope he sold me.  It made me wonder if he was 
acting as a blind front for a previously banned seller.)