Other useful test equipment (was: RE: Scope use...)

From: Corda Albert J DLVA <CordaAJ_at_nswc.navy.mil>
Date: Fri Jul 21 15:13:24 2000

> -----Original Message-----
> From: Douglas Quebbeman [mailto:dhquebbeman_at_theestopinalgroup.com]
> Sent: Friday, July 21, 2000 3:17 PM
> To: 'classiccmp_at_classiccmp.org'
> Subject: RE: Other useful test equipment (was: RE: Scope use...)
>
>
> > I'll second that. I picked up a used HP 16xx something or
> other with 4
> > pods of 8 inputs each, and it's been so useful debugging my home
> > designs. An alternative would be a PC parallel port
> based model, but
> > they seem kind of cheesy compared to a nice, solid, HP unit.
>
> I used an (older?) HP Logic Analyzer that appeared to be an embedded
> Macintosh; I never opened it up to make that determination, though,
> as it was on lease.

I don't know about the earlier HP units, but I think a number of
the really _early_ designs for logic analyzers were based on some
of the microprocessing systems available at the time. At one
time I had 2 logic analyzers, both made by Nicolet, separated by
a few years. The innards of the earlier (and smaller) unit turned
out to be a repackaged Apple II. the later unit was a Z80 based
CP/M unit with a built-in 5.25" drive. It even came with a
CP/M boot disk that turned the unit into a general CP/M machine.

>
> Are these the vintage of units that are being dumped?
>
> -dq
>

No, I didn't mean to imply that any particular manufacturer's units
were being dumped on the market... although I have noticed quite
a number of HP1631A and D systems at the hamfests in my area
of the country (VA-MD). My current analyzer is a HP1631D, and I
paid < $200 (with probes.) It has a 200 Mhz sample rate (50 Mhz
analog bandwidth.) It can even display analog waveforms, so you
can use it as an Digital O'scope in some situations.
We still use this same model where I work, and I am
very pleased with it.

BTW, A number of pieces of HP equipment of this era (circa 1985)
shared the same physical "look", i.e. the HP1631D Logic analizer
looks virtually identical the the HP54201D (and HP54101?)
Digital O'scopes (unless you pay close attention to the
button legends and nameplate), so If you happen across a
stack of identical HP equipment at a hamfest, don't assume
that they are all the same model from simply a casual glance.

One last word on test equipment. Unless you are into vintage
test equipment collecting (a very respectable hobby in it's own
right!) I suggest that you try to get the most modern/reliable
version you can _reasonably_ afford, especially if your point
in obtaining it is to use it to debug something else. This goes
for O'scopes as well as Logic Analyzers, meters, etc.
As any engineer will tell you, you want to reduce the number of
variables in a problem you are trying to troubleshoot, and the
last thing you need in such a situation is a piece of test
equipment that you can't trust. Also be realistic in your
selection. If you have a choice between an 1997 Fluke DVM (in
good condition) and a 2000 "Bonusmart blisterpack special"
you might be much better off choosing the Fluke from a
reliability/dependability viewpoint.

-al-
-acorda_at_1bigred.com
Received on Fri Jul 21 2000 - 15:13:24 BST