Scopes and DMMs

[Tom May]

Barry Bernard <yrrab at well.com> says:

>among other things, Gene wrote...

>>     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.

>  There's a company called Tucker in Dallas that has a catalogue featuring
>reconditioned Tektronix and Hewlett Packard stuff. The prices look pretty
>reasonable. I bought a Tektronix spectrum analyser from them about a year
>ago for work, and it's held up pretty well so far. If anyone wants more
>info on this (like their phone number or something) I'll dig up some info.

If you actually *live* in Dallas (which I have done and don't
recommend), check out JDS Test Equipment.  I checked out a bunch of
places when I was looking for a scope and they gave me the best price
on a Tektronix 465.  They do all the service and calibration in-house.

As far as scope features go (which I think is what the original poster
was mostly wondering about) here's what I use: Although it's a 100MHz
scope, I usually keep the 20MHz bandwidth limiter engaged, so you
*don't* need a 100MHz scope if all you're going to be doing is audio.
I use the dual-trace feature *a lot* to look at outputs vs. inputs,
etc.  I don't use the delayed sweep much, but it is useful for looking
at edges.  I use the channel 2 invert (to re-invert inverting
amplifier outputs) and "sum of channel 1 +/- channel 2" (for
differential signals) quite a bit as well.  It can handle some pretty
large input voltages which I find useful for tube circuits.  I have
never had a use for the single-sweep trigger mode, the external
trigger, or the Z (brightness) input.  I use the line trigger setting
for debugging hum problems.  There is also a high-frequency reject
setting on the trigger coupling that I use a lot to stabilize the
triggering of noisy signals.  And there are some knobs and switches
that are still a mystery to me.  It doesn't have cursors . . . cursors
are very nice, but last I checked scopes with cursors were still
pretty expensive.

As far as DMMs go, all I can say is I hope the next one I get has
autoranging because it gets real old switching between the 200mV and
20V settings.  And that feature where it remembers the voltage after
you remove the probe would be nice, too.

Tom.