1104x-e and 10mhz - Page 1
Forum section: electronics / testgear

author: bobberCHOP
author_rank: Newbie
timestamp: February 10, 2023, 05:35:08 pm
content: So I hooked up a Leo Bodnar gpsdo oscillator to my scope, and the scope is reading 9.99997 MHz. It's all been running since yesterday just the counter doesn't reflect that as I accidentally cut the power, it's all good and warmed up though. Sending a signal to my 5335aHP shows a different story, infact, I'm happy with less than 1hz deviation 10. 000. 000. 53 If I run the gpsdo at 11MHz, it shows dead on from both units???When I send a 10MHz signal from the 5335 back to the scope, I get the same result 9.99997MHz.So what's the deal, is my 1-2 month old scope defunct? The gpsdo is brand new, and the counter just came back from calibration.

author: BillyO
author_rank: Super Contributor
timestamp: February 10, 2023, 06:15:45 pm
content: The stated accuracy of the internal timebase of the SDS1104X-E is +/- 25 ppm.You are measuring a 10MHz signal. That means anything from 9.999750MHz to 10.000250MHz would be within spec.Your reading is only out 30Hz. I'd say that's pretty good.

author: bobberCHOP
author_rank: Newbie
timestamp: February 10, 2023, 06:56:23 pm
content: Quote from: BillyO on February 10, 2023, 06:15:45 pmThank you for the replyI guess I had never takin this into consideration. Is there any way adjusting the the displayed freq. through the menu?

author: tautech
author_rank: Super Contributor
timestamp: February 10, 2023, 07:49:40 pm
content: Quote from: bobberCHOP on February 10, 2023, 06:56:23 pmNo.The system clock is not adjustable and on these entry level DSO's there is no 10 MHz reference input to correct such.Please for the good of the forum learn how to take the small PNG screenshots with the blue Print button and upload a 80kB file instead of a 3MB monster.Another point please, MegaHz is abbreviated as MHz and in an engineering forum we should take some care to get these things correct so not to have any change of being misinterpreted.Great scope bobberCHOP and you'll have lots of fun learning its full capabilities.

author: BillyO
author_rank: Super Contributor
timestamp: February 10, 2023, 08:14:36 pm
content: If you really wanted it to show it smack on to someone. you could take a screen shot as tautech suggested (insert USB mem-stick, press blue button) then edit it with photoshop or some such.

author: tautech
author_rank: Super Contributor
timestamp: February 10, 2023, 08:35:24 pm
content: By chance the Bodnar pulser and 50 Ohm termination was on the bench and prerelease SDS1104X-E within reach as bobberCHOP's waveform didn't look right, presumably unterminated.By shit luck on a cold boot my scope registers 10 MHz although just using the HW counter and internal Measurements as they don't have the resolution.However recent work with $$ SDS6204A has the Bodnar frequency displayed as a little under 10 MHz albeit that from from extended sessions after some hours since boot.

author: bobberCHOP
author_rank: Newbie
timestamp: February 10, 2023, 09:49:48 pm
content: Quote from: tautech on February 10, 2023, 07:49:40 pmFixed, fixed, and 😊 thanksStill learning the forums, so don't know all the tricks yet.

author: 807
author_rank: Frequent Contributor
timestamp: February 12, 2023, 03:02:48 pm
content: Quote from: bobberCHOP on February 10, 2023, 09:49:48 pmDon't know what your attachment looked like before you edited it, but it's too small now. Can't see any detail at all.Perhaps a minimum resolution of around 800 wide would do.My Leo Bodnar mini GPSDO gives the exact same reading as yours on my 1104X-E as well, 9.99997MHzDid you use a scope probe? The waveform is a weird shape.

author: jonpaul
author_rank: Super Contributor
timestamp: February 12, 2023, 04:12:51 pm
content: Used Leo B GPDSO for many years, very reliable and sensitive antenna input, usually locks in 30 secUse the LB utility to see the lock status.By definiton a GPDSO locked to GPS must have exact accurate freq.Your scpoe is wrong.In my lav, Yokogawa, TEK, Lecroy y have an external REF FREQ input for the clock.Otherwise digital measurements like period, freq will have the internal XO/TCXO error. Some may have a trimmer cap to set the xtal to 10.0000 MHz.See if your Chinese copy scope has an EXT REF in and the requirements.Jon

author: tautech
author_rank: Super Contributor
timestamp: February 12, 2023, 10:36:48 pm
content: Quote from: jonpaul on February 12, 2023, 04:12:51 pmMine is wrong too.Note the difference between Counter and Measure Stdev and particularly the Count# which for the Counter is running much much slower so maybe some averaging hides the real frequency instability that is shown in Measure Std Dev.Chinese copy scope, really what planet are you on Jon ?No one ever has made a DSO for $500 with the capability of the 4ch SDS1000X-E range. No one.Their internal reference is accurate enough for most tasks as BillyO points out so an external 10 MHz reference was omitted from the design some 5 years ago.Please indicate where I can find the external reference input on a Tek TDS2012B ?There isn't one as it's not required on this class of instrument at this price point..

author: 2N3055
author_rank: Super Contributor
timestamp: February 13, 2023, 01:45:26 pm
content: Quote from: jonpaul on February 12, 2023, 04:12:51 pmThat is inexpensive scope that cost less than one of the Tek probes you like so much. Read this sentence again. Very powerful, excellent scope. That thousands of people are doing serious work with, every day.It is working from it's own timebase and it has 3 ppm error (the factory spec is 25ppm) which is factor 8x better than promised. OP didn't specify at what temperature his/her lab is.I would say our Chinese friends did splendid job here. Before they started selling these very inexpensive and excellent devices, most us from the west couldn't afford most of the western made T&M devices, unless they were really hoby grade or old stuff from whatever source. That applies to both hobby users but also for small companies. And yes, in this case Chinese are better friend to us than USA (or German) companies selling inferior products at extortionate prices...I choose who is good or not by how they treat me, not by what "sales pitch" and false promises they give. Talk is cheap.