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Old 19th Apr 2021, 11:14 pm   #1
knobtwiddler
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Default Large Screen Oscilloscopes

Hi,

I've been after a large-screen CRT scope for a while, but haven't really known where to look. A recent thread in the tape group here revealed this link (thanks to Lawrence for posting it):

https://worldradiohistory.com/hd2/ID...h=%22airmec%22

A quick web search suggests that Airmec scopes are very rare, which begs the question, did any other firms make 19" scopes? I believe there was a 12" Teledyne model, but do not know the number. From what I've seen, the Airmec looks quite serviceable (assuming one can get the valves). I'm imagining that a later solid-state one might be trickier in this regard.

Any pointers?

TIA
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Old 19th Apr 2021, 11:31 pm   #2
Herald1360
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Default Re: Large Screen Oscilloscopes

That Airmec 'scope would only be of use at audio frequencies. The orange screen most likely will be a long persistence type too.
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Old 20th Apr 2021, 12:45 am   #3
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Default Re: Large Screen Oscilloscopes

I imagine the main problem is that 'scope CRT's needed to use lower max. deflection-angle electrostatic X / Y plates, for wide bandwidth rather than 110deg TV deflection coils. And so you need a much longer neck relative to screen size, making larger ones not very practical.

I was surprised there was a 12" one, but looking at that Airmec one it isn't too deep, and does have very-low 10kHz bandwidth.
- It seems it was intended to be a Schools demonstrator unit, rather than a particularly good proper 'scope.

I recall there were later-on in the the 80's all-digital TV-Scope add-on units, to use a TV as one (but with much reduced bandwidth etc.)
And once solid-state 'scopes became Digital-Storage only, with no direct analogue mode, then you could have a much larger built-in conventional CRT monitor built into it - before they finally switched to widescreen LCD's.

Last edited by ortek_service; 20th Apr 2021 at 12:54 am.
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Old 20th Apr 2021, 2:13 am   #4
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Default Re: Large Screen Oscilloscopes

I'm not sure the airmec uses electrostatic deflection. Given its bandwidth, it could be magnetic.

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Old 20th Apr 2021, 5:48 am   #5
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Default Re: Large Screen Oscilloscopes

HP made a large screen version of the 140A series the 143A, unfortunately these are impossible to find. Another member on here had the 143S version and claimed to have given it away (only hope it wasn't scrapped as the manual didn't go with it).

If in the unlikely event that one does turn up, make sure to collect it yourself as the CRT neck will get snapped off by rough handling, as one in the US did.

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Old 20th Apr 2021, 8:00 am   #6
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Default Re: Large Screen Oscilloscopes

A few weeks back a friend who is a businessman asked me if I wanted an old Airmec tv screen size scope. I said no. It was skipped along with some other gear. Time and storage cost money, so it was the easy option in the current situation unfortunately.
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Old 20th Apr 2021, 8:17 am   #7
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Default Re: Large Screen Oscilloscopes

As David says, I did have an HP 143 and I did give it away. A search of this forum and my emails hasn't identified who, it was many years ago.

David, didn't you end up with the Kikusi large screen scope? That was electromagnetic deflection and will only do 10kHz or so, unlike the 143 which managed 20MHz.

Would have thought that any digital scope could put the display on any size screen you want?
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Old 20th Apr 2021, 8:49 am   #8
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Default Re: Large Screen Oscilloscopes

Airmec 279.
The manual says 17" screen, with very long persistence orange screen. Display is 9" by 13".
Four Y amplifiers, switching in sequence, , DC to 10khz, to 18cm per volt.
Two alternative Time Bases, either 1 sec to 1 millisec or 30sec to 500millisec.
CRT is AEI 31F12, 70deg, with electrostatic focus and magnetic deflection.
No date on manual, but current in 1962.
I'll scan the maual if anuone wants a copy. Amazing bit of history.
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Old 20th Apr 2021, 9:15 am   #9
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Default Re: Large Screen Oscilloscopes

The Tektronix 7603 has the largest 'proper' scope tube I have seen. And its one of the cheapest to buy in series.

dc
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Old 20th Apr 2021, 9:23 am   #10
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Default Re: Large Screen Oscilloscopes

Thank you, all!

The scope is for audio use, so BW doesn't need to be high (although 10K is about the lowest I've ever seen!).

TTi made a digitiser unit that added storage to analogue scopes. I don't think that it can connect to general TVs. I guess a Picoscope could be employed... I'd need to find a monitor. It won't look as sharp as a nice analogue scope, though.

My ideal giant-screen scope would have a phosphorescent screen and look a bit like an Airmec. It's mostly for fun, for when clients visit. I have a small collection of analogue scopes, which get used occasionally (instant response), but in truth, the daily driver is a boring digital scope. Maybe I should use the analogue scopes more often, as a means of keeping my mental arithmetic in order...if you don't use it, you lose it!
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Old 20th Apr 2021, 9:25 am   #11
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Default Re: Large Screen Oscilloscopes

Quote:
Originally Posted by dave cox View Post
The Tektronix 7603 has the largest 'proper' scope tube I have seen. And its one of the cheapest to buy in series.

dc
I managed to get one off a member of the group -) I keep eyeing up the 7L5 plug-in for it, but they are very pricey for what would essentially be a bit of fun.
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Old 20th Apr 2021, 9:40 am   #12
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Default Re: Large Screen Oscilloscopes

There is also an XY Tektronix display, the 620 is one of a series with a few MHz of bandwidth.

dc
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Old 20th Apr 2021, 9:51 am   #13
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Default Re: Large Screen Oscilloscopes

Thanks, Dave.

A quick search suggests that, like the 7603, they are more plentiful in supply stateside. I shall keep an eye out for a 620 in Blighty.
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Old 20th Apr 2021, 10:08 am   #14
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Default Re: Large Screen Oscilloscopes

The HP 1311A was a 14" X-Y display with a 1Mhz bandwidth. I've been meaning to turn mine into a scope since I aquired it in 1987 !

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Note the stylish wood effect sticky backed plasic (HP original!)...

Cheers
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Old 20th Apr 2021, 10:19 am   #15
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Default Re: Large Screen Oscilloscopes

I think the term you're looking for is 'Formica'. Mmm, nice -)

I shall keep an eye out for that one, thanks.
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Old 20th Apr 2021, 10:54 am   #16
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Default Re: Large Screen Oscilloscopes

PS, there are a series of Tektronix XY displays, there is some detail on this page. IIRC the 620 is the small dot / ultra high resolution variant.

Do you need to display real-time signals, or is just for demonstration / post event viewing ? If you don't need real time then a PC with a decent monitor would be a possibility.

dc
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Old 20th Apr 2021, 12:08 pm   #17
knobtwiddler
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Default Re: Large Screen Oscilloscopes

Thanks, Dave.

It is for showing clients stuff. But I'm after something with an aesthetic like the Airmec, ideally. I shall check out the Tek suggestions.
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Old 20th Apr 2021, 2:53 pm   #18
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Default Re: Large Screen Oscilloscopes

Some of these large-screen XY displays were used to display vector graphics (where a computer moves the beam around with a couple of DACs rather than having the beam scan a raster and turning it on at the appropriate times).

My limited-ish experience is that DEC and Tektronix XY displays were magnetically-deflected, whereas the HP ones were electrostatic. The latter certainly means a special CRT which is impossible to find as a spare part.

Some of the Tektronix ones used storage CRTs with all the fun that involves.

The little DEC one I have (VR14) uses a normal CRT but the EHT generator is a can (probably oil-filled) containing a mains transformer and voltage doubler circuit. A circuit diagram is printed on the can. I suspect the output of that, like most mains-produced EHT supplies, is lethal. The HP and Tektronix diplays use a more friendly high-frequency transforner supply.

The HP1311 shown earlier is missing the stand. This supports the unit from a pivot shaft on each side so you can tilt it. Said shafts line up with the center of mass of the unit of course. The top and bottom plastic covers come off the chassis very easily, there then plug-in PCBs for most of the functions and there's an extender board inside the unit. Look out for the cartoon of the electrocuted cat on the EHT circuit in the service manual (!)

One unit to drive the HP1311 is the HP1350 'graphics translator'. This takes in a subset of HPGL over an HPIB interface and displays it as vectors on the HP1311 screen. What makes it odd is that it's all random logic. A microcoded design would, I think, have been a lot simpler.

Tektronix made an 8-channel multiplexer and timebase unit to use their XY displays as a low-bandwidth 'scope. I can't remember the model number, something like 4701? I can dig out the manual if anyone is interested.
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Old 20th Apr 2021, 3:42 pm   #19
Trigon.
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Default Re: Large Screen Oscilloscopes

Quote:
Originally Posted by TonyDuell View Post
The HP1311 shown earlier is missing the stand. This supports the unit from a pivot shaft on each side so you can tilt it.
I think the stand might have been an option - I don't recall it coming with one when purchased new (at work - 1981?). It was rack mounted it in a panel which fitted in the groove visible in the surround.

A few years ago I sprayed the covers black - the original 'putty' colour had darkened in patches and become really quite unpleasant, and fitted feet to make it free standing. Still didn't quite get around to making it a scope though!

I does indeed have an extender board stashed inside, which I always thought was quite impressive. I wonder if you have that service manual as .pdf ? If so, I'd be very pleased to have a copy - just in case...

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Old 20th Apr 2021, 6:41 pm   #20
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Quote:
Originally Posted by woodchips View Post
As David says, I did have an HP 143 and I did give it away. A search of this forum and my emails hasn't identified who, it was many years ago.

David, didn't you end up with the Kikusi large screen scope? That was electromagnetic deflection and will only do 10kHz or so, unlike the 143 which managed 20MHz.

Would have thought that any digital scope could put the display on any size screen you want?
Hopefully it's still out there somewhere then. In the 15 years I've been collecting vintage HP I've only seen three 143x series for sale, two 143A in the US and one 143S in Germany, the serial numbers should give a clue that not too many were made.

HP 143A serial no. 171.
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HP 143A serial no. 149, it took the owner of this one a year to find a replacement CRT after the original was destroyed in transit. It was sold again with a lot of plug-ins.
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Another on here; https://retrovoltage.com/tag/hp-143a/

HP 143S serial no. 277 spectrum analyzer version, still accepts the scope plug-ins.
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I have the Kikusui 512AS Alignmentscope, it's currently in storage with a lot of my test equipment, didn't manage to take any pictures before either.
We had two similar large screen X/Y scopes (can't remember the make) at work with long persistance CRT's used for drop-testing of DC motor armatures, think they have both disappeared now.

David
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