Re: Favourite Test Equipment

john larkin <jl@650pot.com> wrote:

On Mon, 01 Apr 2024 17:37:49 +0100, Cursitor Doom <cd@notformail.com>
wrote:
 

On Mon, 01 Apr 2024 09:15:42 -0700, John Larkin <jl@997PotHill.com>
wrote:
 

On Mon, 1 Apr 2024 12:09:00 -0000 (UTC), piglet
<erichpwagner@hotmail.com> wrote:
 

Jan Panteltje <alien@comet.invalid> wrote:

On a sunny day (Sun, 31 Mar 2024 18:41:18 +0100) it happened Cursitor Doom
<cd@notformail.com> wrote in <9k7j0jlnbhs8qfg5m17pium0835meean83@4ax.com>:
 

Hi all,
 
I'm starting to get a bit fed up with having my test equipment blow up
just when it's needed. This is the drawback with vintage gear; if it's
not used frequently then it can go *bang* the next time you switch it
on. It makes for good practice in repairing stuff, but wastes a lot of
time which could be better spent doing other things.
I think it's time I modernised my test gear. I was just wondering if
anyone has any recommendations they can share. Is there a particular
piece of test equipment you couldn't live without? Something you're
particularly impressed with? I'd be interested to know so I can
perhaps acquire said item and thereby reduce the number of explosions
I experience.
 
Thanks,
 
CD.

 
My 10 MHz Trio dual trace analog scope is from 1979 or there about, I
blew up a channal once myself in the first week
when I accidently touched a booster diode in a TV I was repairing with
it, fixed it locating the problem with the other channel.
Later I cracked the graticule when a soldering station fell on it from
the table (scope stands on the ground)
Made a new graticule.
So, and still working perfectly, OK for all things I build with micros.
For RF to about 1.6 GHz I use RTL_SDR USB sticks and the spectrum analyzer I wrote.
and for AC DC measurements I have some made in China digital meters and an analog one.
also a Voltcraft clamp-on meter for current when you do not - or cannot
interrupt things with the meter impedance.
Also have a Voltcraft soldering station.
Blew up one of my digital meters a while back (volts on the resistance
scale) but fixed it again (replaced resistor).
Many other test equipment I designed and build, like amplifiers LF and
RF, SWR meter, radiation meters, gamma spectrometer,
GHz stuff for satelite, transmitters low and very high power, what not,
a frequency converter to use the RTL-SDR sticks and so the spectrum
analyzer on higher and lower frequencies.
Have a SARK100 SWR analyzer too.
Things last forever here...
Scope used on a regular basis..
RTL-SDR stick 24/7.
Digital meters used every day.
Use my self designed lab power supply every day..
What more do you need?
Learn to use the stuff, understand what's important, and that is it
When I started in electronics as a kid I did not even _have_ a meter,
still stuff worked.
Build my own scope at some point back then when I somehow got the parts
Not much pocket mony as a kid.
UNDERSTAND your systems, what electrons do.
Showing of with boat anchors may impress people, especially the clueless...
But it does not help you one bit.
Anything with an accuracy better than 1 percent in most cases is just
like apes screaming load trying to impress other apes.
 
 
 

 
Many wise words there.
 
Boat anchors can still be great as they require you to understand better
what is being measured and don’t hide things away with abstraction and
unhelpful software.

 
A color digital scope is fabulous. It can measure volts and time and
frequency, save and analyze waveforms, display pre-trigger, and you
can lift one with one hand. And the traces are in color!

 
I know they have their advantages, but they can also tell lies by
showing glitches in waveforms that are internally generated by the
scope rather than the DUT.

 
I've never seen that. Aliasing is obvious.
 

Some instruments do kick crap out of their inputs. I have an otherwise very
nice Krohn-Hite tunable filter box that is hard to use because of its
terrible kickout.

Scopes generally don’t do that, because there are vertical amps and
attenuators in the way.

However, you do need to understand a little bit about how sampling works.
For instance, say you’re looking at a noisy signal. You want to see some
more detail, so you start cranking the horizontal scale knob to the right.
Everything looks fine until you get past the maximum sampling rate.

The scale keeps getting finer, but the display breaks up completely,
turning into a lot of nearly vertical lines. Of course that’s because it’s
gone from real-time to equivalent-time sampling, but it’s puzzling the
first time you see it. (To the analog-only folks: ET is useful, but
requires careful attention to triggering and averaging. )

In general, 1980-2005ish vintage boat anchors really rock, but you have to
get the best. Just yesterday I bought a Tek TDS 684C—1 GHz BW, 4 GS/s
simultaneously on all four channels, with fabulous knob response. It was
$300, about 1.5 cents on the dollar versus new.

When I was at IBM, bought one brand new in the late 90s (probably $20k) and
used it for nearly everything. 

 

For such occasions, it can be very useful
to keep an old analogue scope. I've got 13 of 'em!

 
I have several oldn Taks on carts, as antiques, but I never expect to
power them up again.
 
We do have a bunch of 11801 samplers that still work. They are all
solid-state except for the raster-scan CRT.
 
 

I’m a big fan of those too, and use them often. I have a very nearly
complete collection of sampling and O/E heads, too—just missing the SD-32
50 GHz sampler.

Right now I’m working on a lab amplifier, based on three paralleled
SAV-331+ pHEMTs. Characterizing its noise performance is turning out to be
a bit of a puzzle, despite a pile of top-of-the-line boat anchors, but I’ll
keep that for its own thread.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics