Getting a Free Tek DSA602: What exactly is it?

[DarkStar]

One of my friends is getting three Tek DSA602 "oscilloscopes" that were recently upgraded and taken out of service. He asked me if I wanted one and since I've been looking for something to get started with, said "Sure!"

He told me that it is a 2 Ghz oscilloscope, but when searching online, I'm not finding a whole lot of info on it.

The Tek Wiki (http://w140.com/tekwiki/wiki/DSA600) indicates that it is a "digital scope with waveform processing capabilities." Does this mean that it can be used as both an oscilloscope and a spectrum analyzer?

Since I'm also expanding my horizons in amateur radio, I would be especially interested in the spectrum analyzer portion!

Checking the tutorial on the Tek Wiki for this unit, it refers to using the Tek Pocket Signal Generator throughout the process. Is this something I should pick up from eBay, or would a basic signal generator be a decent substitute?

[kripton2035]

it seems more to be an 1ghz oscilloscope with a 12 channels logic analyzer
sorry no spectrum analyzer ! and old stuff ...

[DarkStar]

Definitely old stuff! Thanks for the info!

[PA0PBZ]

These are real badass scopes the size and weigth of a small fridge... Capabilities depending on what plugins there are. And yes, I have one 

[tekfan]

Nice to see that people actually own these things.

Yes, it is massive. My bench is literally reaching its breaking point because of the weight.
The scope has 1GHz analog bandwidth with the proper plugin (11A71 or 11A72) and has 2Gs/s sample rate. Truly awesome for the time and still useful today. Autocal feature enables the vertical and horizontal accuracy to be well within of the stated 2%.
The touch screen is a very nice feature and works surprisingly well. This was probably the most expensive scope you could buy in 1986.
The only downside is the slow response time when you change timebase settings and vertical scaling. The response time is about the same as the lower end digital scopes of today (Rigol DS 1152e). I'm used to analog scopes so this only gets turned on when absolutely necessary.

The spectrum analyzer is basically just an FFT analyzer but unless you have a standalone one that's all you're going to get out of an oscilloscope. It also has phase analysis and all sorts of measurement parameters you haven't even heard of.
If you have any older Tektronix 7000 series plugins, they can also be modified to fit in the DSA602.
Otherwise the desirable plugins are:
11A34 - 4 channel 350MHz selectable 1M/50ohm
11A32 - 2 channel 400MHz selectable 1M/50ohm
11A72 - 2 channel 1GHz fixed 50 ohm
11A71 - 1 channel 1GHz fixed 50 ohm
11A33 - 1 channel 150 MHz differential comparator selectable 1M/1G/50ohm input (very nice for analysing a tiny bit of AC on a large DC voltage)

These plugins were also offered with 75ohm input impedance for TV work.

You don't need the pocket sig gen. A function generator is more than enough to get used to working with this thing.

A few other things to consider:
There were two versions of this mainframe. DSA602 and DSA602A. They are exactly the same but the A means that it has a 3,5'' floppy drive. It's nice for storing waveforms but the same can be done with the GPIB or RS-232 or even with the printer connection at the back.

Be sure that there are no power up errors displayed. They can be caused by the mainframe itself or by the malfunctioning plugins. One known fault is an error on the acquisition board. The fix is to just resolder the memory chips and that will cure the problem.

There are many hybrid ICs inside that have large heatsinks bolted to them. The interior must be clean and free of dust in order that the temperature does not rise too much and cause them to fail. If that happens your best bet is to get another complete board assembly to repair it. Don't operate it too long with the covers removed because there's no airflow across the heatsinks. All 3 fans must be turning otherwise there's not enough airflow. There's a temperature sensor inside that will regulate the fan speed in order to keep it at a constant temperature.

There are 3 memory backup batteries inside that will have to be replaced soon so you don't risk loosing the calibration constants.
Easily replaced with new 3V lithium batteries that will last for another 15 years.

Whatever you do, don't use the side handles to carry it. They WILL tear off. The later versions of the scope purposely don't have the handles because of this reason.

An added bonus is that it can be used as a heater during the winter. And you thought that only the Tek boatanchor tube scopes get hot.

All in all a very nice digital scope if you have the space for it and the plugins are included.

[free_electron]

Predecessor of the later 800 models ?

Keep in mind that that 2gs/s is NOT realtime ! it is single shot. These are digitizing scopes ( not the same as a digital scope)

They use a scrambled clock around the trigger point to reconstruct the signal. you can only watch repetitive signals.

Realtime they sample like 100KHz .. or less

they are typically used to make eye-diagrams , do TDR and other stuff.

[Jay_Diddy_B]

Hi,

I am the owner of a DSA602A. I can confirm that the DSA602A has two 1G samples per second digitizers for a total of 2Gsps.

The DSA602A really belongs to the 11000 series, because they use the same plugins.

Some of the 11000 series like 11401/11402 do have the slow sampling rates (20Msps). The 11801 is a sampling scope with only 200ksps.

Jay_Diddy_B

[scubywhon]

DSA602A and DSA602 have four 500MSPS digitizers allowing four channels concurrently at 500MS/s, two channels at 1GS/s or one channel at 2GS/s based upon interleaved digitizers yielding max one channel performance of 25ns/div at 2GS/s REAL TIME sampling, NOT Effective Time sampling as suggested.  Using Effective Time sampling the DSA602a resolves down to 50ps/div at an effective sampling rate of 1000GS/s to record 512 sample points of 512ps signal duration gathered over 256 nano-seconds.  You can then select options to automatically gather a set of repetitive single-shot acquisitions and perform averaging and statistics to extract the characteristics of the signal and it's anomalies (so you would not be limited to sampling just pure continuous sinewaves).  However, the analog bandwidth has a maximum capability of 1Ghz by using 11A71 or 11A72 plugin amplifiers.  So yeah, it is a beastly yet very capable scope.  There are some analog signal flow propagation delays amongst all the available channels and plugins configurations, though not a big impact on use.

I replaced the floppy in my DSA602a with a GoTek USB floppy emulator and just use a usb 2Gb stick to transfer files, just had to change OEM jumpers on the USB emulator drive to make work and had to use the DSA scope to format the USB stick.  DSA602 (without 'a') does not have floppy option, so RS232 or GPIB for data transfer.  I've had two DSA602a in my "lab" for several years and both have performed perfectly throughout, so I trust their reliability knowing I can salvage parts if necessary to repair from donor units.  I think the scope is amazing for what it is capable of, just as long as you don't have to transport the beast.  Actually, the plugin amplifiers I collected from ebay have been pretty good for the most part with reliable operation as well.

[wkb]

Definitely old stuff! Thanks for the info!

Definitely old, yes.  We had them at Philips Information Systems.  That was back in 1989 or thereabouts..

But neat and capable stuff.  Just needs lots of space, and preferably its dedicated trolley.