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From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design,sci.electronics.repair
Subject: Re: Favourite Test Equipment
Date: Fri, 5 Apr 2024 17:04:22 +1100
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On 5/04/2024 2:04 am, John Larkin wrote:
> On Thu, 4 Apr 2024 11:56:23 -0000 (UTC), Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
> 
>> Klaus Vestergaard Kragelund <klauskvik@hotmail.com> wrote:
>>> On 01-04-2024 09:01, Jan Panteltje 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.
>>>>
>>>
>>> Very true about specifically the 1% statement. Sidebar, at an earlier
>>> employment, we needed to equip a new lab. Guys wanted GHz scopes. When
>>> asked if the ever looked at edges faster than 1ns, no one did.
>>>
>>>
>>
>> It’s true that there are a lot of relatively undemanding jobs in
>> electronics. You can get on fine with a 200-MHz scope if all you’re doing
>> is PIC and Pi and ham radio and analog TV.
>>
>> It’s also true that you can often make do with what you have—the most
>> important test instrument is the one between your ears.
>>
>> In the before times, doctors were much better with stethoscopes than they
>> are now.
>>
>> But I’d sure prefer a cardiologist who could use tomography and ultrasound
>> over the best stethoscope guy.
>>
>> And it’s a lot easier finding gigahertz oscillations if you aren’t limited
>> to a 10-MHz
>> scope with scale marks in cuneiform.
> 
> We have a product in development, a new digital delay generator, that
> had too many picoseconds of excess, erratic jitter. Turns out that the
> 50 MHz LC oscillator squeggs at about 6 GHz, which I guess is my
> fault. We found that with a spectrum analyzer, not a scope.
> 
> My new oscillator, using a BUF602 as the gain element, looks good.
> Jitter is under 10 ps RMS at 5 usec out, which is great for a
> triggered LC.

But it's rubbish for a free-running oscillator

https://ieeexplore.ieee.org/document/7331424

https://spectrum.ieee.org/for-precision-the-sapphire-clock-outshines-even-the-best-atomic-clocks

You need a system architecture that can exploit a free running clock. I 
came up with one that worked in 1988, and I'm sure that there are others.

-- 
Bill Sloman, Sydney