From: grego@bit.UUCP (Greg Sanguinetti)
Newsgroups: sci.electronics
Subject: Re: Basic bench equipment query
Date: 16 Dec 92 21:05:09 GMT
Article-I.D.: bit.537
Reply-To: grego@bit.UUCP (Grego Sanguinetti)
Organization: BIT  Portland, OR

In article <BzB8rD.BDp@hfglobe.intel.com> dcovell@hfglobe.intel.com (David Covell) writes:
>
>I'm preparing to outfit myself with a basic bench setup, ie scope, function
>generator, power supply, DMM, and transistor tester (lots of in-circuit
>go/no go testing). As always when I begin to shop for things I start with
> ...
>The scope is the biggest decision and the one that could save me the most
>money. My options range from a basic 20Mhz Elenco at $400 to a Tektronics
>TAS series 60Mhz with auto-setup, cursors, known quality, etc at $1550.
>Both Tek and Fluke claim you should go for a bandwaidth of 5X the fastest
>signal you plan to read; just how true is that? I'm sure that if you need
....
the 5x rule is not an issue with audio, obviously since you'ld have a hard
time finding a scope that slow! From the description of your needs I would
go for something higher than 20MHz since you plan on looking at 20MHz digital
signals. I have debugged a 20MHz system with my 60MHz Tek scope. I had no
problems finding the faults (at least problems relating to scope bandwidth).
If you are seriously into digital systems (I am not, as a hobbiest anyway)
then a high speed digital sampling scope is what you want.

For audio, two channels is a must. I often look at inputs v.s. outputs or
overlay one channel on another looking for interferance.
Digital readout is quite handy, I wish my scope had it but it's too old.
I haven't looked around lately but it seems like most of the scopes had
built in DMM readouts and often frequency counter readouts. You should
be able to defer the purchase of a separate DMM for a while especially if
you have a decent hand-held unit now.

I have an old surplus scope that I got when I worked at Tek. It doesn't
have some of the newer features like cursors and digital readout. I don't
miss the cursors and I use my DMM with it, though this is not always
practical while probing. My old scope has more ways of triggering than I
have ever figured out how to use. It is much more flexible than most new
scopes but I have not found use for most of its flexibility. Setting up
a scope for audio work is trivial so auto setup is not of interest to me
and it doesn't deal with the real issues like properly grounding the probe.

The input amplifiers on Tek scopes are very robust and THAT is an important
feature, especially when probing tube amps and making a booboo if you
know what I mean.

>DMM's another hard choice; The Fluke 79 has most of the features I want
>(in fact maybe more than I need). I'd prefer something cheaper than it ($185)
>but it has a high range for capacitance (to 9999uF) and the Touch-hold    
>feature, which will be handy in freeing me from trying to look at the
>meter while probing a 480V tube plate.

These are very nice features. I wish I had them.

-grego (has this been of any help?)
-- 
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Grego Sanguinetti, Bipolar Integrated Technology | Water, water everywhere,
grego@bit.uucp or grego%bit%ogi.cse.edu          | but I'd rather drink
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Newsgroups: sci.electronics