Thoughts on used scopes bang/buck

Electronics
#1

Yesterday at the space, another member and I were discussing best bang for the buck in 500MHz or higher oscilloscopes for mainly analog work. I took some time to put some thoughts together and thought it may be of general interest, and may stimulate some discussion.

This is focusing on used scopes via Ebay:

I am not a huge fan of the older Tek digital scopes, mainly because of their shallow memory depth. I used a TDS784D in school, and it was fine, but limited how much of a long waveform I could observe, or how much detail. That was a big deal.

The Agilent/Keysight MSO/DSOX2xxxA and MSO/DSOX3xxxA scopes are already a generation or more old, and are good all around scopes for embedded/mixed-signal work, especially if you don’t need touch screens (the later -T versions have touch screens but are more pricey used. Various options such as serial decode are expensive but very useful for real work. But, depending on your inclinations, hacks can be found to enable options (not that I condone it. . .)

I like the Agilent/Keysight DSO/MSO 7000, 6000, and 8000 series as well. You’ll pay quite a bit for options such as serial decode. But, depending on your inclinations, hacks can be found to enable options (Which again, I am not condoning. . .)

If you want a 1 GHz scope for mainly analog use, the best bang for the buck will probably be the LeCroy scopes. These scopes are just superb. Even better, LeCroy has officially released PAL source code to enable all options on their 9800 and LC (and I think WP950/960) series scopes, so you have tons of features.

Caveats: They are aging. CRT’s can have burn-in, but also can be replaced. These older scopes (98xx, LCxxx, WP9x0) require special adapters to get the max single-channel sample rate.

Some to look out for:

LeCroy LC574AL/AM: Perhaps the best value anywhere in a 1 GHz scope. 4 Gs/s sample rate and 8MB memory depth. High end professional scope with loads of advanced features and deep memory, plus a built in printer for screen capture (also captures to floppy disk and GPIB). I’ve seen these working under $1000.

LeCroy 9384L, 9384AL, 9384TM: Similar to the LC574, but black and white. Can be had under $1000 as well.

LC684/684D - Nice 1.5GHz scope with loads of features and color screen, nearly as good as the WavePro 950/960. Perhaps the best bang/buck for a 1.5 GHz scope. Can be found in the $1000-$2000 range. Don’t pay more than $2000.

The DDA-125 is a LC684D with some disk-testing features you’ll never use, and two buttons dedicated to disk functions instead of something else (can’t remember what). Same price range as LC684D.

Lecroy WavePro 950: A 1 GHz scope with color LCD screen and built in printer, and loads of high-end features with deep memory. You should be able to find one in the $1500-$2000 range if you are patient, but many folks ask for more. Again, I wouldn’t pay more than $2000.

The WavePro 960 is also great, and a 2GHz scope. Prices overlap the 950, so you may get a bargain. Prices go higher, because it’s still a superb high end 2GHz scope for analog and RF work. The DDA-260 is a WavePro 960 with some buttons dedicated for disk drive analysis (DDA) and some extra DDA options.

WavePro 7xxx/7xxxA: High end windows-based scopes starting at 1GHz for 7100/7100A. Sometimes you can get great deals on these scopes. I’ve seen them go for less than $2000, but you have to wait for the Ebay cycles to go up and down and get lucky. Often they go for $3-$5K for 2-3 GHz models, and are worth it. If you can snag one for a good price, they are pretty nice. They have touch screens, and built in notebooks for capturing and annotating experiments, and great on-screen annotation features. (Note, this is not the same as the older 7200 series scopes.) One more thing I like about these, that is different from other LeCroy scopes, is that they are one knob per vertical channel, instead of multiplexed.

Any thoughts?

#2

I always liked the 784Ds. I disliked the trade-off of numbers of active channels and the memory depth. But I really liked (particularly for analog work) that the channel front-ends had built-in 50-ohm termination and 1M ohm termination selections.

#3

I like that feature as well–it’s important. All of the scopes listed above share that feature.

One more thing about the Tek is that it saves waveforms in a proprietary format that preserves timebase and scaling info, but which needs to be extracted and decoded before you can use the data.

#4

@artg_dms perhaps this is a good time to get a moderate speed (1Ghz) scope for the E-lab?

#5

Can we get a class on how to use them also? :smile:

#6

Not currently seeing the demand for such. $2k is a lot of money to tie up in one piece of gear that probably wouldn’t see that much use. Stay tuned.

#7

Ebay shows $1K for the LeCroy if you look around a bit


Also I think the same argument could be extended to a lot of stuff at DMS.
I for one would like to be able to probe medium speed data lines for FPGAs (200Mb/s or so).

#8

WIth a 2 Gs/s sample rate, it’s not a very effective as a 1 GHz scope. Also, I think you have to have a special adapter to get the max data rate.

Here’s how the LeCroy scopes work. Suppose you have a 1 GHz 4 Gs/s scope. You have 4 interleaved 1 Gs/s DACs. If you run all 4 channels, you get 1 Gs/s. If you use only one of channels 1&2 and one of channels 3&4, you can get 2 Gs/s, and if you use a special splitter adapter for channels 2 and 3, you can interleave all 4 DACs to get 4 Gs/s.

So, I’d stay away from the 2 Gs/s scopes for any more than 500 MHz. for 1 GHz,

Note that the Wavepro 950/960 are 16 Gs/s, the WavePro 940, DDS260, and LC684D are 8 Gs/s.

Also the LeCroy scopes come with various memory options. Shoot for VL or XL when you can.

#9

Even better: