Should I buy Tektronix TDS 360 or Fluke PM3394A?

[ThangNguyen]

Hi,
This is my first post here  .
I would like to buy an oscilloscope for my growing hobby which is robot stuffs. Currently I am using a myRIO (NI's realtime + FPGA controller). This myRIO has 40 MHz clock rate. I decided to buy a 200 mhz oscilloscope. Right now my choice is narrow down to Tek TDS 360 or Fluke PM3394A. There is one thing concern me which make me prefer the Fluke is calibration. The Fluke has auto calibration feature while the Tek does not and it use NVRAM to store all of those information. But another side Tek has 1Gs/s while the Fluke has 200Ms/s. So I still not sure which one should I peak for current work and future, I really need your input.

Thank ahead for your time reading and answering my post.

[edavid]

Hi,
This is my first post here  .
I would like to buy an oscilloscope for my growing hobby which is robot stuffs. Currently I am using a myRIO (NI's realtime + FPGA controller). This myRIO has 40 MHz clock rate. I decided to buy a 200 mhz oscilloscope. Right now my choice is narrow down to Tek TDS 360 or Fluke PM3394A. There is one thing concern me which make me prefer the Fluke is calibration. The Fluke has auto calibration feature while the Tek does not and it use NVRAM to store all of those information. But another side Tek has 1Gs/s while the Fluke has 200Ms/s. So I still not sure which one should I peak for current work and future, I really need your input.

Of those 2, I would pick the PM3394A, because:

1. has useful analog mode
2. 4 channels instead of 2
3. record length 32Kpt instead of 1Kpt (still skimpy)
4. better control layout
5. service manual available

However, if you have the money for a Rigol DS1054Z, that would be a better choice than either of these classics/boat anchors.

[rustybronco]

Read this post before you decide if the 1K record length is too skimpy for your needs.
https://www.eevblog.com/forum/testgear/first-scope-tektronix-tds220-vs-rigol-ds1052e/msg475389/#msg475389

And then try it with the TDS220 using the delayed timebase instead of zoom.  If you have a short record length, then the delayed timebase works in place of zoom as long as you are not looking into the pretrigger record and some old oscilloscopes can do even that although it is implemented in a different way.

To quote a PM I received... "The delayed timebase function on the TDS360 makes up for and is superior to a large record length in most applications."

This won't help you with the two channel Vs. four channel issue, but the 1 Gs/s sure beats 200 Ms/s.
NVRAM dying is a distinct possibility. I bought a Dallas DS1644-120+ to keep as a spare.

The service manual for the TDS360 can be found here. https://doc.xdevs.com/doc/Tektronix/TDS340A/tds340a_service.pdf

[ThangNguyen]

@edavid: Thanks for your info. But the bandwidth of Rigol DS1054Z is only 50 mhz. And I need to spend more money too.

@rustybronco: Thanks for your info. When you have to change the NVRAM, you have to redo calibration right? As far as I know it cost money for that since I cannot do it by myself.

[edavid]

@edavid: Thanks for your info. But the bandwidth of Rigol DS1054Z is only 50 mhz. And I need to spend more money too.

You can upgrade it for free to ~ 150MHz bandwidth.

@rustybronco: Thanks for your info. When you have to change the NVRAM, you have to redo calibration right? As far as I know it cost money for that since I cannot do it by myself.

If you are very careful, you can read the old NVRAM contents with a programmer and copy to a new one.

[vltr]

One thing to remember with that era tek scope is the bad electrolytic capacitors.  If it hasn't been recapped you're probably going to want to do that before they go. 

[edavid]

One thing to remember with that era tek scope is the bad electrolytic capacitors.  If it hasn't been recapped you're probably going to want to do that before they go.

TDS300 series doesn't suffer from this problem.

[vltr]

One thing to remember with that era tek scope is the bad electrolytic capacitors.  If it hasn't been recapped you're probably going to want to do that before they go.

TDS300 series doesn't suffer from this problem.

Ah very good, I spent waaay too long recapping and rebuilding traces on my 410 it has made me very shy of all the scopes with the same physical design.  I'm glad the 300s can go back on the list.

[ThangNguyen]

So it still comes back to 1GS/s VS Calibration 

[rustybronco]

@rustybronco: Thanks for your info. When you have to change the NVRAM, you have to redo calibration right? As far as I know it cost money for that since I cannot do it by myself.

It is possible to do it yourself. "As I know it" you would need an accurate DC voltage source (up to 90V?), two 50 ohm terminations, two 3 foot BNC cables and a  fast rise time generator.  I suspect the latter device could be made or had rather cheaply.


Yes, Calibration is the issue. As someone else suggested, desolder the NVRAM and clone it. Note, it's not without pitfalls.

What's the price difference between the two?

[ThangNguyen]

I search on eBay and found TDS 360 about $250 while the PM3394A is about $300.

[rustybronco]

I paid $125 shipped for my TDS360.
http://www.ebay.com/itm/Tektronix-TDS-360-Digital-Oscilloscope-Parts-Repair-75/401298370096?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Cal expired 10-15. 18 months past.

Either model you choose, weigh your ebay choices carefully. You can get stung.

$15.68 shipped. (It was a P6117 200Mhz probe )
http://www.ebay.com/itm/Tektronix-P6109B-Accessories/161936105201?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

$20.61 shipped.
http://www.ebay.com/itm/Tektronix-P6109B-100mhz-voltage-probe-w-detachable-ground-clip/252830868376?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

[rustybronco]

Do you need 200 mhz bandwidth?

TDS340 100 Mhz 500 Ms/s with options. $65.00 + shipping. 2 channel, has cal stickers on it. http://www.ebay.com/itm/TEKTRONIX-TDS-340-OSCILLOSCOPE/382136330530?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D41375%26meid%3D78a897ec69db4fb7bbd93d74ee118050%26pid%3D100005%26rk%3D5%26rkt%3D6%26sd%3D122550371017


http://www.toughdev.com/content/2014/01/exploring-tektronix-tds-340-100mhz-digital-storage-oscilloscope/

Cheap-cheap...
Just a thought.

Please get other opinions on it if you do decide

[ThangNguyen]

Good price 

[ThangNguyen]

I have just ordered this
http://www.ebay.com/itm/TEKTRONIX-TDS-360-TWO-CHANNEL-DIGITAL-REAL-TIME-OSCILLOSCOPE-200MHZ-1GS-s-H10/272717768527?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Calibrated 02/2017 Due 02/2019

and

http://www.ebay.com/itm/Pair-of-Tektronix-TPP0201-200MHz-10X-Passive-probe-x2/322537049249?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

I am trying to limit the money I spend for my hobby as possible since I need to buy other parts too. I may sell it later to buy the Rigol.

[Paul Moir]

Keep up on the Dallas NVRAM:  the drop in replacements are going obsolete.  Looks like Digikey has 10 left of the DS-1644P.

[ThangNguyen]

@Paul Moir: After look at your post, I search on Digikey and saw 10 available but when I bought it turned 0  . Luckily I found on eBay and bought 2 from there  .
Thanks for reminding me.

[rustybronco]

More likely than not, those chip's on ebay will be clones.

[ThangNguyen]

@Rustybronco: Does the clone work?
Is the DS1644P-120 a dip type or power cap type?

[rustybronco]

Don't know. I haven't tried the one I purchased off Ebay yet. But it's a nice looking clone!
http://www.ebay.com/itm/DS1644-120-Package-DIP-28-Manu-DALLAS-Nonvolatile-Timekeeping-RAM/252854007618?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Is the DS1644P-120 a dip type or power cap type?

The one in the TDS360 is a DIP package.

[edavid]

More likely than not, those chip's on ebay will be clones.

That's silly, there's never been a Dallas NVRAM clone spotted in the wild.

What you see in the secondary market are old date codes, and possibly remarked date codes

[rustybronco]

What you see in the secondary market are old date codes, and possibly remarked date codes

The date code on mine is 1608A3C.



https://media.digikey.com/pdf/PCNs/Maxim/M000910I.pdf
https://media.digikey.com/pdf/PCNs/Maxim/M000843A.pdf

https://groups.io/g/TekScopes/messages?expanded=1&d=&msgnum=105106

Thank you for your interest in Maxim.
| The DS1644-120 is out of production as you pointed out.
| Datasheet:

Post dated 2014.

I could be wrong, but $7.00 USD for a part which normally sold  somewhere in the $40 USD range leads me to suspect the EBAY part.

(Image added)

[alm]

Pretty sure I have seen reports of fake NVRAMs in the Keithley 2001 repair topic. So I highly doubt the never spotted a fake Dallas NVRAM comment, unless you want to argue that Maxim-branded DSxxxx parts are somehow different.

[rustybronco]

IIRC the DS1644-120+ had a minimum order of 1K. I can't find the link at the moment. I did a far amount of searching before I bought the one that I did.

It's anyone's guess at this point.

[edavid]

Pretty sure I have seen reports of fake NVRAMs in the Keithley 2001 repair topic.

Citation please?  Is it clones or fakes we are talking about?  And how could you distinguish a fake part from a bad, remarked part?

So I highly doubt the never spotted a fake Dallas NVRAM comment, unless you want to argue that Maxim-branded DSxxxx parts are somehow different.

I was referring to the comment about clones, not fakes, and I was lumping together Dallas and Maxim.

But that does raise the point that any part that is marked Dallas is pretty suspicious, since Maxim bought them in 2001.  I don't know the history of the package markings though.