State of the art oscilloscopes - 10 years ago

[tautech]

I think that Tektronix should re-release the TDS200-1000 series
cases as a promotional lunch box or tool box, I'd buy a couple.

 

Muttley

Yep, as Dave will attest, they would keep your lunch or tools dry. 

[Muttley Snickers]

20 year anniversary promotion, 

Well sort of were all this compact DSO stuff started from I guess.

PS; I never accept version 1 of anything, my girlfriend is version 6.2


Muttley

[rs20]

The quiz is interesting.

Anyone get it?

I'm not well-versed in transistor amplifier layouts (I mean, I know my amps with resistors on both the collector and emitter, gain = -R1/R2 but once we leave that realm I'm out of my comfort zone) so I don't fully grasp the question in the sense that I don't really know which topology is supposed to have a gain of 200. It doesn't seem at all surprising to me that it has a gain of 1800, because I have no particular expectation of what it should be at all. All that aside, SPOILER ALERT, I think it's strange that R4 is connected to the output, not to positive supply. That means that it's parallel to the fixed ~0.7V V_BE of T2, and has a more-or-less fixed current running through it. V_B, and therefore the output (=V_E), can swing wildly with only small changes in I_E(T1), since those changes feed in full through to I_B(T2). Small changes in input leading to wild swings in output voltage = high gain in my books. The same argument could be made for R3 (in other words, T1 is missing a resistor on its emitter, so by the three-resistor **model** the gain is "infinite"), even though it's not so weird-looking to me intuitively, so, yeah, that's just a handwavy thought.

How wrong am I? 

[pomonabill221]

I have a Tek 7834 analog 400Mhz (in reduced scan mode), with a 7a18 / 7a13a / 7a22 verticals and a 7b92a horiz delaying time base plugins.

Bought it about 10 years ago for 400 at a surplus store.

Got the service manuals for it and cal'd it.

It was the SAME mainframe that I used at Hughes Aircraft in El Segundo (EDSG) in the 80's... I know this because of the pencil marks on some of the knobs, and the coffee mug ring on the top of the cover!

Trying to sell it now as I have the Rigol DS1052E (upgraded to the 1100), but of course shipping is ridiculous and nobody wants that old of a scope!

A real oldie but goodie!

[pomonabill221]

R4 is positive feedback....

R3 / R2 / R1 set the bias on T1 and signal is decoupled from T1's base by C1.

[TerraHertz]

The quiz is interesting.
Anyone get it?

T2 is an emitter-follower. Since R4 sees a constant Veb across it, it acts as a current source to collector of T1.
The LF operating point of T1 is set by the R1, C1, R2 LP filter, to bias T1 just into conduction. Then for small signal inputs T1 is acting as a current gain amp, into the very high impedance of the current source of R4. Resulting in very high voltage gain.


On the topic of old scopes, I had a lucky ebay buy recently. Not a scope, but an original Tektronix 7000 Series Oscilloscope Product Line Catalog from 1973.  63 Pages, in perfect condition. I think the owner kept it sealed in a bag the last 40 years. A lovely piece of history.
Anyway, another item on my 'to scan' list.
Here are a few photos.

[Howardlong]

Anyway, I am looking forward to trying out the 1980b when it finally arrives. It has the four channels, digital storage, plot/sequence and key sequence ROM options whatever they do. I'd imagine the digital storage is little more than just that, a screen shot almost, and the single shot sweep in particular looks really a bit limited from the limited information I have.

When I first saw a 1980b I thought it was a thing of wonder. I wondered where these guys had got the budget to buy one. 

The 1980b is really uninteresting when you use it for single shot storage. However, if you have the right plugin it will give you 1GHz bandwidth as a sampling scope, and that was pretty exotic in its day.

Well I finally received the unit just before the xmas break. Wow. As well as a bit of X-Y work before the break, I spent a few hours with "her" today, on real work. Just beautiful.

Vid: http://youtu.be/BXOHyjeLAXM



I must get out more.