OT - CRT's

The new Keysight infivision 'scopes do a great job at X-Y.

Clean and fast...

George H.

My digital scopes can do Lissajous figures in XY mode, but I never do that. They can measure phase accurately.

A CRT can't really measure anything accurately.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

With a digital scope, wait until you have a beautiful waveform, hit STOP, and capture that for the manual.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

Our usual bench digital scopes can measure edge timings to 30 picoseconds, and the big LeCroy gets below 1 ps, with 1 ps RMS jitter.

Look up "the sampling theorem." One can accurately measure times to a very small fraction of the scope's sampling rate.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

We make an I-Q modulator box that works in the 10s of MHz. One production test will verify the 90 degree channel. We'll use a 500 MHz Rigol scope and automate the testing. It will measure the phase shift accurately if we're careful about the cable time delays.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

When I was a kid, I'd set up a Lissajous display at parties. Yes, I was a geek even then.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

It's fun to connect two good oscillators to a dual-trace scope. Say a rubidium and a caesium or GPS. Trigger on one and look at both. Sweep maybe 10 ns/div. Check every few hours and see if anything has moved.

Infinite persistance is useful for a lot of time and jitter measurements. Analog storage scopes were really awful.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

All our analog scopes eventually died, the last one being the 1 GHz Tek 7104, the one with the microchannel plate.

I don't think any of our digital scopes has ever failed.

The only thing I miss about analog scopes is the exotic plugins, the super gain differential switchable-bandwidth things. Fabulous for low-level stuff. You can buy external boxes that do most of that.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

On a sunny day (Wed, 22 May 2019 07:27:29 -0700) it happened John Larkin wrote in :

Yes, this one outputs 2.4 GHz On the analyzer you can see carrier sideband and suppression down to about -50 dB, sideband suppression should be maximum if the 90 degrees is correct. I use fixed tones and frequency sweep 240 Hz to 2.4 kHz (audio range) I and Q to drive an AD8346 QAM modulator directly at 2.4 GHz

Want to test some capacitors, ordered this from ebay yesterday:

These SMDs 10nF 1% seem OK, and a lot smaller than the big 1% ones I have now:

maybe I will order some and select for close matches / lowest tolerance. Not in a hurry, watching movies,... Yes, that Rigol is attractive, and would also do fine for audio range phase shift measurements. You could also do some zero crossing detection and set reset a flip-flop by I and Q and measure its output pulse width for audio as value of the phase shift.

It isn't the CRT doing the measurement, but the operator.

An operator who is aware of the limitations of the tools being used can get accurate results with quite crude tools, though they do tend to improve the tools to get more accurate results.

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Bill Sloman, Sydney

Yes, in oscilloscopes. There is stuff that cannot be properly detected on a digital oscilloscope, especially when it comes to random noise from sources whose noise pattern isn't known a priori. The jobs where you have to see "fuzz on fuzz" and sometimes figure out a pattern in the unwanted fuzz to find out where that comes from. Many times I have dragged an old analog scope scope from a client's clutter cabinet, did a quick emergency "resurrection" on it and found their problem. Other times we did an EBay rush order for a Tektronix 2465 or similar.

You can still buy analog scopes, in part for the above reason. Iwatsu makes high-end ones and lower cost versions can be found on Amazon.

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Regards, Joerg 

http://www.analogconsultants.com/

You too? I'd hook up the right speaker to one chan, and left to other. (That was in grad school, once I'd scored a free 'scope from the physics department.) (I seem to recall having some issues with how ground was attached.) Hey these days it would be fun to have a DSO show the time and frequency domain.

George H.

snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:

Finding replacements is the thing. They (lab gear) are typically NON standard.

A good CRT maker still doing it is Thomas Electronics

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Your fingers will add/change capacitance as you squeeze that.

My AADE meter came with a plug-in PC board that has a narrow gap in the topside copper. I can zero the capacitance then bridge the gap with a surface-mount cap, and push it down with the back end of a wooden q-tip or a toothpick. That seems to be good for low-c caps.

I guess the real way to measure small caps would be to connect some pcb pads to the meter, measure that, then solder in the cap and measure again.

I could make a pc board to help doing that. Next proto board maybe.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

John Larkin wrote in news: snipped-for-privacy@4ax.com:

They can 'tell you' if a tornado is approaching with the right input setup.

John Larkin wrote in news: snipped-for-privacy@4ax.com:

very

hit

It was a joke, Johnny. Those of us in the discussion... it is a good bet that we all know what a DSO is,

John Larkin wrote in news: snipped-for-privacy@4ax.com:

John Larkin wrote in news: snipped-for-privacy@4ax.com:

I took apart my first laser disc player, which happened to have a HeNe laser and little optrical bench inside it, That bench had two electrically "swingable" mirrors in it. I removed the prism reflector, and sent a sine wave to one and music into the other, and pointed the beam up at the ceiling. Cool stuff. Same wave into both and WOW... Lissajous! Exciting as a kid.

On a sunny day (Wed, 22 May 2019 08:43:38 -0700) it happened John Larkin wrote in :

Yes, and no, yes because of course it will, but no because I can zero too:

I use the LCP program I wrote for it, and zero by simply pressing the spacebar. So zero by pressing spacebar, grab C, let go of clip, read value. Shoud work I hope.

Yes, OTOH for 10nF capacitors 1% is 100 pF and should not be a problem.

I have a little boxes full of Chinese SMD caps, but those came with caps in unmarked plastic bags in the boxes, had some strange effect that if I selected 47 pF measured frequency and then replaced it with 33 pF then the frequency was lower... So not sure China man put right bags in right boxes... That sort of problems takes a lot of time to find.