Scopes and DMMs

[gstopp at fibermux.com]

     Regarding features on 'scopes and DMM's....
     
     I use a DMM for the following:
     
     1. Measuring and calibrating CV's to 1V/octave
     2. Matching resistors for CV input summers and discrete DAC's
     3. Measuring and adjusting power supply voltages
     4. Measuring capacitor values (not all meters have this)
     
     Plus your normal resistor-measuring and short-finding stuff. The 
     Realistic jobs from Rip-Off Shack are fine for me. No real need to 
     spend a bunch 'o bucks on a Fluke, unless you find a sale. To be 
     totally honest absolute calibration is not as important to me as 
     repeatability.
     
     Everything else, I use a scope. At home I have an old crummy Heathkit 
     10M that's out of calibration and has a dim trace. But it gets me 
     around - at least I know how it will display what I need to know, and 
     usually that's enough to stop most explosions before they happen. When 
     I need to do actual measurements for specifications etc. I use the 
     stuff here at work and pray that my boss is in a meeting or something.
     
     For analog synthesizers, my favorite is a Tektronix 100 MHz four-trace 
     with cursors. The images are clean and sharp, and the cursors let you 
     measure waveform frequencies and periods and amplitudes without having 
     to count divisions and keep a calculator handy. (We're not talking 
     laziness here, we're talking speed.) I rarely use more than one trace 
     at a time. I realize that this is a bit overkill for home expectations 
     but it would be the reference point if I were to buy something.
     
     Most of the junk here at work is logic-analyzer oriented HP stuff but 
     we do have a few big nasty HP Frequency Synthesizers that goes from 
     subsonic to many megs with perfect analog waveforms. I would never 
     dream of trying to own such a box. HP stands for "high-priced".
     
     I would really hate to think about how much it would cost to buy 
     something like a Tektronix for personal use. Are there low-cost 
     cursor-display scopes out there these days? I'd say that 10 MHz is too 
     slow, and 100 Mhz is better than needed, so 50 MHz would probably be 
     perfect.
     
     - Gene
     gstopp at fibermux.com
     

______________________________ Reply Separator _________________________________
Subject: Scopes and DMMs
Author:  Bob Zimmer <bzimmer at voicenet.com> at ccrelayout
Date:    5/1/96 10:24 AM


Now that I finally have enough parts and schematics, I'm ready to try some 
building and am looking to buy a scope and a new DMM (I do have a Frequency 
Counter and Analog Multimiter).
     
What I'm wondering is just what features are needed in a scope to calibrate 
analog modules.  I don't want to limit myself to just being able to use it 
on these (looking for a good general purpose unit?), but don't have the 
money for a 1 GHz Tektronix either!  Are features like delayed sweep, 40 MHz 
or better speed, cursors, etc. necessary? or simply luxuries?  Back when I
had taken Electronics Courses, they just didn't exist! (Am I dating myself???)
     
Also, I've noticed that both Protek and B&K sell 4 1/2 digit DMM's with 
basic DC accuracy of 0.05%.  The Protek sells for $100 list(???) and the B&K 
is discounted to about $180.  I know that for this price, there are many 
choices in 3 1/2 digit models with all the bells & whistles and .5% basic DC 
accuracy, but am wondering if getting a basic features only, more accurate 
unit would be a better choice.  Also if anyone is familiar with Protek, they 
sell two versions of their 4 1/2 digit DMM.  One which is portable and the 
other a bench unit.  
They appear to have identical specs, but the bench unit is $279 list vs $100 
list.  I know that an internal power supply and larger case don't add up to 
the $179 difference.  What gives?
     
Any recommendations???