opinions on buying a scope

[tempus fugit]

Hey all;

I'm thinking about adding a couple things to my test equipment arsenal, and
I was thinking about a scope. I've seen quite a few on eBay going fairly
cheap, but I'm not sure what I need for capability (or even if I really need
a scope) My main diagnostic tool is a DMM. I mostly work with audio stuff
(built and designed few things) and the odd repair for a family member of
some piece of consumer gear, so I don't need anything too intense I don't
think. What kind of bandwidth is useful? I'm guessing there are some older
scopes out there with such limited bandwidth as to be useless anymore (maybe
that's why they're so cheap). What about a PC scope (hardware or soft -
although I suppose the software type will be limited to 20kHz bandwidth).
Can anyone point me to a good tutorial site on how to use a scope,
applications, tricks, etc?

Thanks

 

[Dr. Anton Squeegee]

In article <IUTSa.215$uW3.99@nntp-post.primus.ca>, tempus fugit says...

Hey all;

I'm thinking about adding a couple things to my test equipment arsenal, and
I was thinking about a scope. I've seen quite a few on eBay going fairly
cheap, but I'm not sure what I need for capability (or even if I really need
a scope) My main diagnostic tool is a DMM. I mostly work with audio stuff
(built and designed few things) and the odd repair for a family member of
some piece of consumer gear, so I don't need anything too intense I don't
think. What kind of bandwidth is useful? I'm guessing there are some older
scopes out there with such limited bandwidth as to be useless anymore (maybe
that's why they're so cheap). What about a PC scope (hardware or soft -
although I suppose the software type will be limited to 20kHz bandwidth).
Can anyone point me to a good tutorial site on how to use a scope,
applications, tricks, etc?

If you're never going to do much with RF, I suggest poking around
ham swap meets or Ebay for a Tektronix 7603 mainframe. Along with it,
get a 7B53 timebase plug-in and a 7A26 or similar vertical plug-in.
You'll end up with a very nice 100MHz big-screen 'scope for, at the
most, about a dollar per MegaHertz.

If you do anticipate doing things with RF in the future, I would
suggest looking for a Tektronix 7904 or 7904A. This is a 500MHz
mainframe. For timebases, use a 7B92A for the main one and a 7B85 for
the delaying/delta time. For verticals, again, the 7A26 is a good
starter. You'll want a 7A29 if you want to take full advantage of the
7904's bandwidth.

Don't go the PC route. Contrary to (seemingly) popular belief,
PC's are far from the Answer to Everything in the test equipment world.
By the time you get done kitting out your PC, you'll have exceeded the
cost of a good 7603 'scope with plug-ins, and you'll have something that
won't give you nearly as good value for your $$.

Good hunting.

--
Dr. Anton Squeegee, Director, Dutch Surrealist Plumbing Institute
(Known to some as Bruce Lane, KC7GR)
kyrrin a/t bluefeathertech d-o=t c&o&m
"Quando Omni Flunkus Moritati" (Red Green)

 

[AC/DCdude17]

X-No-Archive: Yes

"Dr. Anton Squeegee" wrote:

If you're never going to do much with RF, I suggest poking around
ham swap meets or Ebay for a Tektronix 7603 mainframe. Along with it,
get a 7B53 timebase plug-in and a 7A26 or similar vertical plug-in.
You'll end up with a very nice 100MHz big-screen 'scope for, at the
most, about a dollar per MegaHertz.

Good choice. If he wants the ability to capture "freeze" an instantaneous signal,
I would suggest 7633. It's almost like the 7603 with storage capability.

I happen to have a pair of 7A26 amplifiers and a 7B53 myself and they work well

If you do anticipate doing things with RF in the future, I would
suggest looking for a Tektronix 7904 or 7904A. This is a 500MHz
mainframe. For timebases, use a 7B92A for the main one and a 7B85 for
the delaying/delta time. For verticals, again, the 7A26 is a good
starter. You'll want a 7A29 if you want to take full advantage of the
7904's bandwidth.

I have a 20MHz horizontal scope stored somewhere and it never gave me trouble for
the things I do. I use my Tek because I need the delay function the 7B53
provides.

Don't go the PC route. Contrary to (seemingly) popular belief,
PC's are far from the Answer to Everything in the test equipment world.

PCs make excellent low cost logging devices.

 

[Bob Masta]

On Mon, 21 Jul 2003 11:46:32 -0400, "tempus fugit"
<toccata.no.spam@ciaccess.com> wrote:

Hey all;

I'm thinking about adding a couple things to my test equipment arsenal, and
I was thinking about a scope. I've seen quite a few on eBay going fairly
cheap, but I'm not sure what I need for capability (or even if I really need
a scope) My main diagnostic tool is a DMM. I mostly work with audio stuff
(built and designed few things) and the odd repair for a family member of
some piece of consumer gear, so I don't need anything too intense I don't
think. What kind of bandwidth is useful? I'm guessing there are some older
scopes out there with such limited bandwidth as to be useless anymore (maybe
that's why they're so cheap). What about a PC scope (hardware or soft -
although I suppose the software type will be limited to 20kHz bandwidth).
Can anyone point me to a good tutorial site on how to use a scope,
applications, tricks, etc?

For the use you describe, you probably don't really need any more than
10 MHz or so bandwidth. That will allow you to see if your audio
circuit has spurious high-frequency oscillations, for example.

The main thing you get with fancier scopes besides bandwidth is
all the extra features, like (better) dual-timebase or the ability
to capture a single-sweep trace.

You could get an inexpensive scope, then use a sound-card
based PC package to provide some extra features. I have
a 100 MHz scope on my bench which is mostly overkill... 10 MHz
would be fine for most of the work I do. (Like you, mostly audio.)
But I supplement it with my Daqarta software (plug!) running on
a junk 16 MHz 386 PC with a Sound Blaster card. That
gives me FFT spectra and color spectrograms, which are
extremely handy for monitoring low-level distortion, etc.
And I can generate test signals and use synchronous
averaging to look at responses buried in noise. And
save traces to files for later reference, etc, etc.

And let's not forget the user interface issue. The high-end
scopes that I've used are an absolute nightmare to
learn, if you want to make use of all the advanced
features. PC-based systems have more flexibility in
designing the interface in the first place, and can have
complete pop-up Help systems at the touch of a key.

In short, it's very useful to have both kinds of scope.,
especially since the PC-based version can be very
cheap or free.








Bob Masta
tech(AT)daqarta(DOT)com

D A Q A R T A
Data AcQuisition And Real-Time Analysis
Shareware from Interstellar Research
www.daqarta.com