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| Best Brand Name for an Oscilloscope? |
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| mawyatt:
--- Quote from: tautech on December 01, 2022, 03:00:32 am ---... IIRC SDS2504X Plus BW is nearly 600 MHz and it's reported somewhere in the 2kX Plus thread. First SDS2104X Plus we got hands on is what I tested and as reported in the link to post above and I flat out didn't believe it was ~185 MHz but tested with 3 yes 3 sinewave sources confirmed it was. :o I'd never seen the likes of rated BW exceeded by 85% in any instrument. ... --- End quote --- Recall our SDS2104X Plus after "enhancement" with the kind help of folks here, returned something like 618MHz BW :-+ Best, |
| gf:
--- Quote from: nctnico on December 01, 2022, 01:44:39 am ---And then again, Aliexpress and Ebay are full of low cost HF generator boards that are suitable up to hundreds of MHz with a reasonably constant amplitude. --- End quote --- Yes, but these $$ SI5351, ADF435x, etc. PLL synthesizer boards usually don't output sine wave, which complicates things. However, the amplitude of the fundamental frequency component can still be measured on the scope via FFT if the test point frequencies are chosen such that none of the harmonics alias exactly to the fundamental frequency in the 1st Nyquist band, enabling the separation of fundamental and harmonics via FFT, despite aliasing. If the test point frequencies are furthermore selected such that the fundamental falls onto a FFT bin frequency, then scalopping loss can be avoided. Reference measurements for the fundamental frequency amplitude of each test point can be done with a (tiny)SA if frequency-invariant amplitude is not granted. EDIT: Btw, isn't the tinySA able to output sine wave when used as signal generator? At least the Ultra? |
| nctnico:
--- Quote from: gf on December 01, 2022, 06:36:47 am --- --- Quote from: nctnico on December 01, 2022, 01:44:39 am ---And then again, Aliexpress and Ebay are full of low cost HF generator boards that are suitable up to hundreds of MHz with a reasonably constant amplitude. --- End quote --- Yes, but these $$ SI5351, ADF435x, etc. PLL synthesizer boards usually don't output sine wave, which complicates things. --- End quote --- No it doesn't. Near the maximum bandwidth you'll see a sine wave anyway because the 2nd harmonic is typically not very strong while the 3rd harmonic is 3 times the fundamental frequency. |
| MrAl:
--- Quote from: BillyO on November 30, 2022, 06:24:29 pm --- --- Quote from: MrAl on November 30, 2022, 05:06:40 pm ---Are you using the right probes too? I use 100MHz rated probes. --- End quote --- Direct connection. The FG is a Siglent SDG1062X connected by 18" of coax. The fast risetime oscillator connects directly to the scope input. --- End quote --- Oh ok that sounds good, but i wonder if that 18 inches of coax is affecting the readings. As long as it is good coax i guess you're ok there. I think the FAST family TTL is around 2ns rise time. There are ways around that too by doing a little calculation that includes the rise time of the input wave. If you could have someone with a better scope measure that, i could provide you with a formula to compensate. Interesting little gadget though. What main chip is that based on? That really tells all. |
| MrAl:
--- Quote from: nctnico on November 30, 2022, 10:56:43 pm --- --- Quote from: BillyO on November 30, 2022, 09:05:07 pm --- --- Quote from: tautech on November 30, 2022, 08:25:25 pm ---Are you making these Billy ? --- End quote --- I may, once I have them where I want them and there is enough demand for them. Otherwise I can just make the files available. --- End quote --- Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't. The only proper way to measure the bandwidth of an oscilloscope is to sweep the input using a levelled RF generator. --- End quote --- There is a way to compensate for the rise time of the input wave if that is what you are talking about. Also, when they quote the 0.35 constant what levels are they touting the rise time is measured at? Is it the 10 percent to 90 percent thresholds, or something else? There is also the settling time which is rarely mentioned, which i see affects some digital scopes. |
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