Tektronix 2225 vs TAS 220, which one to keep?

[tmammela]

So, today I made some really good deals. My school wanted to get rid of some stuff so I bought Tek 2225, TAS 220, 10x Tek probe and a Philips PM 5131 signal generator for 30€ total! I did some testing and both seem to work, only problem I found is that in 2225 the single sweep doesn't work OR I don't know how to use it. Every other feature works and after some time turning the knobs, they seemed to clean themselves as I don't get any distortion from changing the settings anymore.

Now, I don't need two analog scopes so one of them is going to leave soon, I already made a deal to sell one but I have few days to decide which one I'll give. So which one is better? I already have some idea of the differences but I'm a noob really so I would appreciate other opinions.   

Time for an image, both have identical settings:

[Nermash]

I would keep the 2225 and sell the tas...

[madshaman]

I find I like the user interface on the TAS series the worst of all tech scopes.

I have a TAS 485, and although it is a beautiful scope, I don't use it as much because I don't like the UI.  I found setting cursors to be annoying for my hand in particular, but your milage may very.  I think Tektronix could have done a better marriage of modern digital control and an analog scope.

I'd second keeping the 2225, it's beautiful and elegant and I reckon that you'll have an easier time maintaining it.

Just my two cents.

[edavid]

If I were you, I would keep both.  However, if I had to choose one, I would keep the 2225.  The reason is that there is no service manual for the TAS220, and I only know of one person in the world who even has the schematics.

[r3l3u]

Both for sure ! If you can ....

[tmammela]

All right, I will stick with the 2225! I did some serious work today with it and it's just great. Much more fun to use than my real workhorse, digital TDS 210, which feels slow and crappy after analog smoothness. The TAS 220 doesn't seem to have very accurate screen and the controls don't feel too good. Also 2225 is a tiny bit smaller.

[c4757p]

I think Tektronix could have done a better marriage of modern digital control and an analog scope.

The 2445/2465/related models, of course... shame they threw that away. Sure, it looks "simpler" with fewer buttons, but buttons are nice. Once you learn their locations you never have to navigate a clunky menu

[madshaman]

I think Tektronix could have done a better marriage of modern digital control and an analog scope.

The 2445/2465/related models, of course... shame they threw that away. Sure, it looks "simpler" with fewer buttons, but buttons are nice. Once you learn their locations you never have to navigate a clunky menu

So totally agree, have a few 2465s and a 2467B, these scopes have a *great* interface (and setting cursors doesn't make me want to throw the scope).

[tmammela]

By the way, anyone know what causes this strange wave form:



Happens below 1 uS per div, voltage gain does not affect it. Dave mentioned the same problem in his video but did not try to fix it. 

[Electro Fan]

I think Tektronix could have done a better marriage of modern digital control and an analog scope.

The 2445/2465/related models, of course... shame they threw that away. Sure, it looks "simpler" with fewer buttons, but buttons are nice. Once you learn their locations you never have to navigate a clunky menu

So totally agree, have a few 2465s and a 2467B, these scopes have a *great* interface (and setting cursors doesn't make me want to throw the scope).

Without a doubt, Tektronix figured out so many things so well with their analog scopes - many of which are fundamental and applicable to digital scopes - but somehow they just didn't manage to stay out in front in developing and commercializing digital scopes with the same excellent level of leadership they exhibited with their extensive line of analog scopes.  I have to believe that there was and still is such a large resevoir of know-how residing somewhere inside the company that even though many of their best people have probably retired or moved on that Tektronix could still potentially produce outstanding digital scopes.  No doubt something happened when they were acquired but if the new ownership would let the horses run they could make a comeback - but every year that goes by probably runs the risk of further losing the edge they once enjoyed.  I'd love to see Tektronix come back strong but there aren't a lot of signs of this happening.

- just try turning a knob on an analog Tek scope and a knob on an Agilent digital scope - one provides very precise feedback, the other is comparatively an adventure

[grumpydoc]

Happens below 1 uS per div, voltage gain does not affect it. Dave mentioned the same problem in his video but did not try to fix it.

FWIW I have a 2225 that does the same - it's on the jobs list

So if anyone does know I'd be grateful for the answer as well, might save me some time.

I assume it's some interaction between the horizontal & vertical amplifiers. First thing has to be to check all the power supply rails and make sure they're in tolerance for voltage and ripple.

[madshaman]

I'm wondering if this effect doesn't originate in the trigger or horizontal sweep circuitry, do those little "kinks" stay, for example, when you're displaying a low amplitude sinewave?  If so, how do the kinks track when you change trigger level, what about horizontal position?

[MarkL]

Happens below 1 uS per div, voltage gain does not affect it. Dave mentioned the same problem in his video but did not try to fix it.

FWIW I have a 2225 that does the same - it's on the jobs list

So if anyone does know I'd be grateful for the answer as well, might save me some time.

I assume it's some interaction between the horizontal & vertical amplifiers. First thing has to be to check all the power supply rails and make sure they're in tolerance for voltage and ripple.

It happens on the 2465 too.  It's there at any vertical sensitivity, but it's more noticeable on the sensitive ranges (2mV/div).  Horizontal or vertical position have no effect.  It's on both main channels and very slight on the aux channels (3 & 4).

The worst wiggle is always 60ns after the start of the beam sweep.  If you set delay mode, where it intensifies a portion of the sweep, the wiggles also appear in the intensified section.  Also of interest is that some of the wiggles move with the intensified section as the delay setting is changed.

Clearly there's some unwanted coupling between signals associated with the beginning of A and B sweep and the vertical amps (suspects: internal trigger, beam intensity/blanking, reflections from the front end of the sawtooth), perhaps occurring through inadequate shielding or through the power supply.

Whatever it is, it's pretty easy to tell that this is a scope artifact and not in the signal source, so I haven't gone crazy trying to track it down.  The absolute worst case on the 2465 is  about 1/10 division and it doesn't really get in the way.

[calexanian]

I realize I am a bit late to this party but I have a TAS 220 at my transformer testing station and use it once a week or so and have never found it wanting. Its just a plain old meat and potatoes scope and I have no complaints. Nothing against the 2225, but they are getting a bit older now. Don't say that to the thousands of them that are out there probably still running just fine every day.

[nctnico]

I second the vote for keeping the TAS220. It's obviously much newer and has cursor readouts. It can probably show the frequency as well which is a very handy feature on an oscilloscope. The lack of a service manual doesn't have to be a problem. A lot of Tektronix designs are similar.

[calexanian]

TAS 220 does not have a freq reading. Only a voltage cursor and the ability to measure between two voltages and blurp out the difference. It displays the settings on the display. Used to be handy for snapping pictures. Now I just hit print on the new scopes connected to the printer.

[VintageTekFan]

The 2225 has up to 500uV/div vertical sensitivity, compared to the TAS220 which has 1mV/div.
50MHz vs 20MHz
No cursors vs cursors.

Those are the biggest differences.

If it were me, I'd keep both. But then again, I'm a collector.

[nctnico]

TAS 220 does not have a freq reading. Only a voltage cursor and the ability to measure between two voltages and blurp out the difference. It displays the settings on the display. Used to be handy for snapping pictures. Now I just hit print on the new scopes connected to the printer.

According to the manual the cursors can be used to display time and 1/time (frequency).
http://f6csx.free.fr/DOC/TEK%20TAS%20220,%20TAS%20250%20User%5B1%5D.pdf