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Richard Erlacher
06/12/12 08:07
Modified:
  06/12/12 08:09

Read: 686 times
Denver, Co
USA


 
#187674 - I must have missed a step ...
Responding to: Mahmood Elnasser's previous message
Mahmood Elnasser said:
I'm searching for more capable scope to buy. I tried the local shops but prices are huge. I borrowed a 100MHZ Fluke 199C to evaluate and buy but to be honest I'm not spending $2000 for such a crap. Speed was acceptable , scope is very easy to use but overpriced.
I was looking at OWON scope 200MHz bandwidth with 16 channel logic analyzer for half price of fluke, but it is chinese and I'm afraid it will be junk.


Since you already have the 200 MHz TEK 475, I don't know why you want yet another 200 MHz instrument.

In the PRC, they don't strive to build rubbish for export. They're "buying market share" by producing goods of acceptable quality at very reasonable prices, as a consequence of which they hope people will recognize their ability to produce quality products. The rubbish they export is, generally speaking, produce at the behest of Western business, e.g. Wal-Mart and the like, who want primarily to have the cheapest products, and quality be damned. Even major brands sold here in the U.S. have "special" versions for the price-war stores. The manufacturers won't even honor a warranty for Wal-Mart, because Wal-Mart, just as an example, has contracted to have a lower-quality product boxed and shipped to them with a Wal-Mart warranty, which Wal-Mart happily honors for the first 90 days, say, as in the case of a television set, but which the manufacturer won't even attempt to repair if it fails after the Wal-Mart warranty expires.

Those people in the PRC are just as capable as those anywhere else, of building quality products. When APPLE hires them to build something cheap, they know what's wanted, and they build it to order. Like Wal-Mart, APPLE knows that people will buy their product irrespective of the quality.

I don't like to buy a used scope, it is ok to spend the money if I get what it says on the box.


Have you had bad experience with "experienced" products? Over the past 15 years, I've acquired lots of used equipment for my clients and for others who've sought out my help in selecting, purchasing, and "testing" used equipment. I've had no problems, aside from one bad incident with a Chinese seller who boxed-up and sent what was obviously a defective instrument at the outset. Email me and I'll give you details, and how to prevent that sort of trouble.

For the FPGA board I can generate clocks with 90, 180, 270 phase shifts so I guess the minimum time step I can generate reasonably is 1.5 nsec. But the clock jitter is about 900 psec. Do you think it is reasonable to generate 1.5 nsec pulses using 300 MHz fpga or shall I try the circuit proposed by the late Jim Williams in the EDN design ideas Nov 11 2004?

Mahmood



I couldn't find the article to which you refer. Perhaps you could provide more detail. I don't know why you're concerned about the extremes of what you can produce with programmable logic. Perhaps you could provide a little more detail about where you want to go with that.

RE


List of 74 messages in thread
TopicAuthorDate
DSO for cheap!      Joseph Hebert      05/11/12 13:35      
   very good      Mahmood Elnasser      05/11/12 14:14      
      Limitations      Joseph Hebert      05/12/12 09:49      
         test results      Mahmood Elnasser      05/12/12 12:46      
            That's valuable information      Joseph Hebert      05/12/12 13:30      
         well, the fact is ..      Richard Erlacher      06/03/12 11:43      
            tektronix 475 comparison      Mahmood Elnasser      06/07/12 10:37      
               Really? Why?      Richard Erlacher      06/07/12 14:51      
               another double post ... sorry      Richard Erlacher      06/07/12 14:51      
   I think ...      Erik Malund      05/11/12 14:34      
      Application dependant      Mahmood Elnasser      05/12/12 05:55      
         Indeed      Andy Neil      05/12/12 09:10      
            It's still too low a bandwidth, wouldn't you say?      Richard Erlacher      06/03/12 11:50      
   just curious, Joe could you try      Erik Malund      05/11/12 14:36      
      Unusual with short pulses for hobbyist projects      Per Westermark      05/11/12 14:53      
         is the clock running?      Erik Malund      05/11/12 16:01      
      Sorry, but no I can't.      Joseph Hebert      05/11/12 16:42      
      10nSec Pulse      Mahmood Elnasser      05/12/12 12:59      
         "at random" means what exactly ?      Jim Granville      05/13/12 18:41      
            Answers      Mahmood Elnasser      05/14/12 07:41      
               more observations      Mahmood Elnasser      06/03/12 10:51      
                  It may not be the sample rate ...      Richard Erlacher      06/07/12 15:07      
                     digital vs analog      Mahmood Elnasser      06/08/12 15:34      
                        Don't get me wrong, here ...      Richard Erlacher      06/08/12 21:34      
                           poor mans's scope      Mahmood Elnasser      06/09/12 02:01      
                              Doesn't it depend on what THEY mean by bandwidth?      Richard Erlacher      06/09/12 20:58      
                                 20 nsec steps      Mahmood Elnasser      06/09/12 23:08      
                                    Well, one thing at a time ...      Richard Erlacher      06/10/12 11:43      
                                    Impulse Tests are better      Jim Granville      06/10/12 16:49      
                                       more capable scope      Mahmood Elnasser      06/11/12 14:03      
                                          I must have missed a step ...      Richard Erlacher      06/12/12 08:07      
                                             TEK475      Mahmood Elnasser      06/12/12 16:16      
                                                here's another alternative ...      Richard Erlacher      06/12/12 22:16      
                                                   DAC and pot in parallel?      Per Westermark      06/13/12 01:07      
                                                      Logically, not physically      Richard Erlacher      06/13/12 07:57      
                                                   new theory      Mahmood Elnasser      06/14/12 00:57      
   3MHz is rather poor Bandwidth ?      Jim Granville      05/11/12 16:51      
      ordinary      Erik Malund      05/11/12 17:20      
         Ther are many params needed      Jim Granville      05/11/12 18:21      
   "only" $200 ?      Andy Neil      05/11/12 23:59      
      Low cost oscilloscopes      Andy Neil      05/12/12 09:18      
         291 > 2*($199)      Joseph Hebert      05/12/12 09:45      
            It doesn't always work that way      Andy Neil      05/12/12 10:48      
               Once upon a time ...      Joseph Hebert      05/12/12 13:28      
   SDS8202      Mahmood Elnasser      06/14/12 13:58      
      Read all the "fine print' first ... and ask any questions      Richard Erlacher      06/14/12 20:31      
         bought it      Mahmood Elnasser      06/16/12 03:07      
            Please let us know how this works out for you      Richard Erlacher      06/16/12 04:19      
               datasheet      Mahmood Elnasser      06/16/12 05:26      
                  2mV/div - but min trig level?      Per Westermark      06/16/12 07:01      
                     Tests      Mahmood Elnasser      06/16/12 09:55      
                        24ns      Per Westermark      06/16/12 11:09      
                           and that's the crux      Erik Malund      06/16/12 11:41      
                              FPGA pulse Expander (edited)      Mahmood Elnasser      06/16/12 12:06      
                                 some love the mother, some love the daughter        Erik Malund      06/16/12 12:13      
                                 Here's omne fairly simple thing ...      Richard Erlacher      06/16/12 15:22      
                                 self calibtrate?      Jim Granville      06/16/12 20:42      
                                    interesting      Mahmood Elnasser      06/16/12 23:01      
                                       yes      Jim Granville      06/16/12 23:15      
                                          glurk      Jez Smith      06/17/12 13:33      
                                             DCMs      Mahmood Elnasser      06/17/12 14:49      
                                                Well....      Jez Smith      06/17/12 15:48      
                                                   I don't know where you're going with this ...      Richard Erlacher      06/17/12 21:25      
                                             xxxxx      Mahmood Elnasser      06/20/12 12:53      
                           333ps      Mahmood Elnasser      06/18/12 00:59      
      SDS9302      Mahmood Elnasser      07/05/12 10:32      
         So, how are you exercising this new 'scope?      Richard Erlacher      07/05/12 10:53      
            so far so good      Mahmood Elnasser      07/08/12 09:45      
               So far so good ...      Richard Erlacher      07/08/12 10:49      
                  rise time      Mahmood Elnasser      08/15/12 13:28      
                     The rise time indicates that high frequencies gets dampened      Per Westermark      08/15/12 16:26      
                     What does "bandwidth" mean?      Richard Erlacher      08/15/12 17:45      
                        good test      Mahmood Elnasser      08/30/12 15:09      
                           Perhaps you should repeat the test ...       Richard Erlacher      08/30/12 23:08      

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