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NNTP-Posting-Date: Tue, 02 Apr 2024 15:09:33 +0000
From: John Larkin <jl@997PotHill.com>
Newsgroups: sci.electronics.design,sci.electronics.repair
Subject: Re: Favourite Test Equipment
Date: Tue, 02 Apr 2024 08:07:56 -0700
Organization: Highland Tech
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On Tue, 2 Apr 2024 09:56:33 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>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. 


You've seen my SDxx sampling head collection. Must have been worth
$250K new, twice that adjusted for inflation.


>
>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. 

Some day my 11802 will die. I'll mourn it.


>
>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. 

The old HP analog noise figure meters got way sub 1 dB, with some sort
of lock-in technique.

I remember some germanium jfets that got below 1 dB at low MHz (for a
Raydist navigation receiver, pre-GPS) and was astounded.

Come to think of it, I slightly helped get GPS started. That's another
story.