[geeks] Tektronix TDS 220

[Dave McGuire]

On July 15, Joshua D Boyd wrote:
> The web site talks about the TDS 2000 series as their low end.   But
> they are making it sound like a digital scope.  For instance, they
> talk about record length in kilo bytes. 

  That's definitely a digitizing scope...it digitizes analog signals
and presents them in a digital form.

> OK, that should be usefull to know.  The TDS 220 is called a digital
> scope in some ads.  Is it a true digital scope, or an analog one under
> digital control?  Looking at the tektronix web site.  It was certainly
> far easier to use than my old analog one.  Plus I appreciated the
> calculations it would do.

  It is indeed a digital scope.  The easier to use part doesn't really
have much to do with it being digital or analog, though.

> OK, at their web site, they seem to indicate that the TDS220 is better
> , but older, than the TDS2000.  However, the lower end still TDS1000
> series looks good enough.

  Yes the 220 is older than the 2000...but that doesn't make much
difference here either.  Scopes generally don't go through the "six
months and it's useless" effect that plagues, for example, PC
hardware.  There are many, many electronics labs, for example, that
are using 25-year-old Tektronix 475s.  For most applications, the few
technological advances that have found their way into oscilloscope
designs don't really affect much in terms of their operational
capabilities.  Sure things like weight/power consumption/heat output
have been reduced, and some ancillary stuff like stored setups and
remote control...but rarely anything in the "scope functionality"
area.  Except for the new crop of LCD-based scopes, they haven't even
gotten any smaller in the past 20-25 years.

> But wait, they don't list a 2200 in the TDS2000 series, so it must be
> another series I'm looking for.

  The 2200 isn't a TDS-series scope.  It's simply the "Tektronix
22xx"...2215, for example.  No TDS.  You probably won't find marketing
information pertaining to those scopes on Tek's web site, because
they're not current.

> Now, I don't know how to fix my one good amp (I'm learning more and
> more about solid state electronics, but it is a tube amp), and I don't

  If you learn about field-effect transistors, you'll have a good head
start on tubes.  Just watch out for B+. 8)

> But, I also have a number of non working items.  A quick test over
> with a DMM didn't really turn up anything, so I'm thinking going over
> them with a scope might help.  If I can make them work, mostly they
> would be easier to upgrade than starting from scratch would be.

  A DMM is the single most useful piece of general electronic
troubleshooting equipment.  A good analog scope (be it ones with
analog or digital controls, though I strongly prefer the latter) would
have to be next.

  For your audio stuff, I would have to recommend either a plain analog
scope or an analog scope with digital controls.  For the stuff you've
been talking about, I would specifically recommend the Tektronix 2445.
I have a great deal of personal experience with this scope...they're
very featureful, built like tanks, have nice on-screen displays,
voltage and time cursors with on-screen digital delta measurements
(very VERY handy...in voltage mode for example, two knobs move two
horizontal lines on the screen and the voltage between them is
displayed textually atop the screen)...small, easily portable, great
for general-purpose work, and amazingly reliable.  It should set you
back maybe $300 or so on eBay, maybe a bit less.  Unless you get into
*fast* digital stuff or VHF/RF stuff, this might be the only scope
you'll ever need.  I would recommend it against any of the TDS scopes
for general work.  Make no mistake, though...this is a high-end scope
that carried a $6K price tag when new.

  There's one on eBay, for example, at
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1748708659.

      -Dave

-- 
Dave McGuire                  "Needing a calculator indicates that
St. Petersburg, FL              your .emacs file is incomplete." -Joshua Boyd