List of test equipment with external 10MHz reference - Page 1
Forum section: electronics / testgear

author: picitup
author_rank: Regular Contributor
timestamp: December 17, 2016, 08:19:41 am
content: Hi AllIt's nearly xmas and I'm considering buying a 10MHz GPSDO but am struggling to find kit with an external 10MHz reference input. It would be great to have this accuracy and sync my kit.I have a TTI TF830 1.3GHz counter which has an external 10MHz input so that's a good start. My scope is an SDS1102CML which doesn't and I have a TTI TG120 20MHz function generator which hasn't.Ideally I'd like a scope and function generator with external 10MHz inputs.I'd like people help to compile a list of test kit which may be useful for many.Thanks for reading....Steve

author: ebclr
author_rank: Super Contributor
timestamp: December 17, 2016, 08:28:04 am
content: Siglent SDG 2042 X have a in / out 10 Mhz sincSiglent SSA-3021-X spectrum analyser have 10 Mhz sinc input____________________________Double Oven OCXOhttp://www.ebay.com/itm/10-MHz-Double-Oven-OCXO-Double-sinewave-EPSON-TOYOCOM-TCO-6920N-10MHZ-/262326560037?hash=item3d13e1a525:g:PKIAAOSwYGFUxRZl

author: EV
author_rank: Frequent Contributor
timestamp: December 17, 2016, 08:35:44 am
content: Rigol DG4000 Waveform Generators have 10 MHz in/out.

author: tautech
author_rank: Super Contributor
timestamp: December 17, 2016, 09:38:23 am
content: Quote from: ebclr on December 17, 2016, 08:28:04 amIn fact all Siglents AWG's except the SDG800 series have 10 MHz ref inputs.

author: TiN
author_rank: Super Contributor
timestamp: December 17, 2016, 10:16:49 am
content: HPAK 33120A in/out

author: picitup
author_rank: Regular Contributor
timestamp: December 17, 2016, 11:03:42 am
content: Thanks all for your suggestions so far. @ebclr thanks for the link to a double oven OXCO. It was so cheap, I bought one and guess if I go for GPSDO I can sell it again for little loss.Does anyone know of a scope with 10MHz external clock input or is that a crazy thing to ask?CheersSteve

author: SingedFingers
author_rank: Frequent Contributor
timestamp: December 17, 2016, 12:59:08 pm
content: Marconi 2019A has a 10MHz ref input.

author: jpb
author_rank: Super Contributor
timestamp: December 17, 2016, 01:07:13 pm
content: My scope sadly doesn't but I use 10MHz ref on my two counters (TTi TF930 and Tektronix FCA3100) and importantly on my Agilent 33522A function generator.It is great having the counter and the generator synched for doing Alan Deviation measurements with mixers.The next thing I'd hope to get at some stage that benefits from a 10MHz ref input is a spectrum analyser but they are a bit pricey.I think it is more expensive scopes that have ref input, but for lower frequency stuff I've thought of using ADC development boards which have clock input.As an example I see the Keysight 6000 series has:http://www.ebay.co.uk/itm/Keysight-Used-DSO6014A-Oscilloscope-4-channel-100-MHz-Agilent-/192030885111?hash=item2cb5eec4f7

author: TurboTom
author_rank: Super Contributor
timestamp: December 17, 2016, 04:35:35 pm
content: Quote from: picitup on December 17, 2016, 11:03:42 amRigol DS / MSO 4000 (and probably also DS 6000) series have 10MHz in- and output.Cheers,Thomas

author: DaJMasta
author_rank: Super Contributor
timestamp: December 17, 2016, 05:39:46 pm
content: Quote from: picitup on December 17, 2016, 11:03:42 amNormally they're for instruments where high timebase stability is critical to accurate measurements - Frequency counters, function generators, some spectrum analyzers, etc. Often, you don't see this requirement on a scope until you start analyzing high speed signals for jitter, where you'd need better accuracy than the jitter of the signal you're measuring to get meaningful results, and that's not typically something that a lower end scope is really capable of. The lowest end current scopes I've seen them on are the Rigol DS4000 series, but if you're counting raw price, you can get 10MHz reference inputs on older scopes that were high end in their series. If you're buying a new scope with a 10MHz reference input, expect to spend at the very least $1000, but more realistically at least $1500-2000 US.

author: Dr. Frank
author_rank: Super Contributor
timestamp: December 17, 2016, 07:38:23 pm
content: HP5370A/B T.I. and frequency counterHP5335A Universal counter (Maybe 5334A as well)HP3325B Synthesizer /Function generator (many similar generators/oscillators as well)Frank

author: Dino KL0S
author_rank: Contributor
timestamp: December 17, 2016, 10:33:30 pm
content: All of my Rigol and Agilent gear that has anything to do with RF accepts a 10MHz reference input; some high end ham radio transceivers are beginning to do so as well. Commercial grade HF receivers have done so for a long time, my TenTec RX-340 included and with the 10MHz reference I was able to do extremely well in the ARRL over the air frequency measurement tests a number of years ago. If you have any plans of adding test gear to your bench in the future you'll be glad you had the reference capability even if your applications are limited now.

author: mmagin
author_rank: Frequent Contributor
timestamp: December 18, 2016, 04:16:00 am
content: I've tended to look at rear panels quite carefully since having GPS-disciplined 10 MHz handy.My experience with 1970s-1990s vintage stuff, things which do:synthesized HP spectrum analyzers (mid-1980s onward)synthesized signal generators.frequency counters beyond entry-level models. e.g. if it goes to 1GHz or higher or it takes up a full rack (and not just by virtue of it being an antique.)HP 5359A time interval synthesizerThings which do not:1990s digital oscilloscopes.HP 8082A pulse generator (some damned fast edges, but it's not about accuracy in the way the 5359A is)non-synthesized audio signal generators.Wavecrest DTS (has an internal ovenized 100 MHz reference however)(not bothering to mention voltmeters, DMMs, etc.)

author: pelule
author_rank: Frequent Contributor
timestamp: December 18, 2016, 09:18:21 am
content: HP 5316B Universal counter (my DIY Universal counter as well)

author: JonM
author_rank: Unknown
timestamp: December 18, 2016, 11:55:15 pm
content: Many (maybe all) models of the Programmed Test Sources PTS-500 frequency synthesizers have 10 MHz reference inputs. I have two PTS-500s, one has a 10 MHz OCXO and the other has no internal reference and requires the 10 MHz signal from the master unit.Jon

author: picitup
author_rank: Regular Contributor
timestamp: January 05, 2017, 02:21:29 pm
content: Hi AllThanks very much for all your replies and sorry for the slow reply myself, I seem to have got sucked into xmas :-)The Toyocom TCO-692N double oven OXCO that @ebclr suggested arrived over the break so I had a play with it. I still want a GPSDO but was pleasantly surprised with the Toyocom.According to the seller, the two 10MHz outputs are only 250mV, so I was expecting to have to build a small amplifier to connect it to my TF830 counter/timer which is marked on the front "TTL". However, as it turned out, the output into my scope measured at 1.92v and the TF830 will accept an input down to 2v (ish), so it worked right out of the box.I warmed up the TF830 for 30 mins, powered up the OXCO and watched the current consumption and frequency. The room was at 16 deg. C.On turn-on, the current at 12v was 600mA and the TF830 measured 9.99970 MhzFor the next 90 seconds, the current increased slowly to a peak of 925mA and the frequency measured crept towards 10MhzAfter 3 minutes, the current dropped to 908 mA and the freq was 9.99999 MHzAfter 4 minutes the current dropped to 600 mA and the frequency flicked between 9.99999 and 10.00000 MhzAfter 7 minutes the current draw dropped to 250mA where it settled. The frequency settled as in 4 Mins above, flicking between the two.I then warmed up my SDS1102CML scope and tried the frequency measurement. It measured 9.99991 MHz so a little out. I have the service manual and it tells you how to check the timebase accuracy with a 10MHz signal, but not how to adjust it so maybe I'll take a peek inside later.Then I tried my UT61e which read 10.000 Mhz.I've attached a couple of pics of my unit, which differs from the pics of the one advertised. My unit has "12-15v" legended on the back of the PCB under the power jack and "amoji1010" and "MO 16.11.16". I asked the seller if I could use 12-15v and he said it's better to use 12v and 15v for not too long. I got the impression that he didn't really know but I used it on 12v just to be cautious.As far as buying kit with 10MHz reference inputs, I think it might be a little expensive for me. I did think that I could use the ref on my TF830 counter/timer and then check the output from my TGI120 function generator, but the TGI120 has a variable pot to change the frequency, and it's impossible to get a frequency bang on as it has no fine control. Hmm....That's all for now and thanks for reading :-)Steve

author: tautech
author_rank: Super Contributor
timestamp: January 05, 2017, 03:36:28 pm
content: Quote from: picitup on January 05, 2017, 02:21:29 pmDid you run a Self Cal first ?There's at least 2 clocks inside them, IIRC 1 @ 100 MHz and another @ 30 MHz.All in the Service manual, you can download it here:http://www.siglentamerica.com/Uploadfile/file/20140925/SDS1000CML_ServiceManual_en.pdf

author: picitup
author_rank: Regular Contributor
timestamp: January 05, 2017, 07:31:14 pm
content: Hi @tautech no I didn't, but I'll do this and report back and thanks for the link.I've left the OXCO and counter/timer running for a couple of hours now and increased the gate time from 0.1s to 10s and gained an extra two digits of accuracy, namely down to 0.1Hz. The upshot is that it's settled down now to 9.9999970 MHz or 3 Hz out at 10MHz. Not too shabby for a standard xtal (non-oven) in the counter/timer.Of course I don't know if this is the OXCO or the counter/timer producing the innacuracy, but I've bought one the the GPSDO's from China so I'll check it when that arrives.

author: picitup
author_rank: Regular Contributor
timestamp: January 06, 2017, 11:31:56 am
content: Hi @tautech I tried warming the scope and OXCO up for an hour, did a Self Cal and the results were the same ie 9.99991 MHz. I wish there was an extra digit of resolution there down to 1Hz, but it is a budget scope so can't complaint too much. So as far as I can tell, my scope is about 90 Hz out at 10MHz which ain't fantastic.Also I was looking for a new function/abstract waveform gen which would take a 10MHz ref input. If I could spend £400-£500 there is a good choice, but my budget is a little lower. I saw the Hantek HDG2022B which has a sexy spec for the price but read reviews on here saying it was junk. I was also attracted to the 16 Channel Digital Output but can only guess on it's function as the only entry in the manual I can find is as follows:16 channels digital output, together with the analog channel can rebuild the more mixed signals in daily practice.Well, that clears that up then! Actually I should remember my experience with my Hantek PPS2320a power supply where they had wound a tapping of the transformer wrong. I guess QC is not their greatest strength lol.https://www.eevblog.com/forum/testgear/hantek-pps2320a-review/I think it's possible that Hantek make very sexy equipment very cheaply that is cr@p :-)I also took a look at the Siglent AWG's as you suggest and these have the 10MHz ref and are quite competitively priced. I think I'll try and get an ex-demo unit or second hand to save costs.CheersSteve

author: tautech
author_rank: Super Contributor
timestamp: January 06, 2017, 07:01:38 pm
content: Quote from: picitup on January 06, 2017, 11:31:56 amSteveI'm sorry I haven't got any CML's here ATM to run a Freq counter comparison for you.....all sold out.Should have some in a couple of weeks so I'll try to remember to do that....remind me later this month.AWGIf you can stretch to a SDG2042X (40 MHz 2 ch) they seem to be the forum favourite ATM as they can beimprovedto 120 MHz.https://www.eevblog.com/forum/testgear/the-siglent-sdg2042x-thread/Or our "new kid on the block", SDG1000X series, not as featured as the 2000X series.https://www.eevblog.com/forum/testgear/siglent-sdg1000x-waveform-generators/Rob

author: Keysight DanielBogdanoff
author_rank: Unknown
timestamp: January 06, 2017, 07:51:58 pm
content: Keysight InfiniiVision 4000 X-Series OscilloscopesKeysight InfiniiVision 6000 X-Series OscilloscopesAgilentKeysight InfiniiVision 7000A & 7000B OscilloscopesAll current Keysight Infiniium Oscilloscopes

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 06, 2017, 08:56:39 pm
content: From memory I think the old Agilent DSO/MSO5/6/7000 scopes can use an external reference for the frequency counter.However it seems a fairly tenuous reason for choosing a scope - scopes aren't generally good for precision measurements.

author: voltsandjolts
author_rank: Unknown
timestamp: January 06, 2017, 10:20:35 pm
content: Quote from: mikeselectricstuff on January 06, 2017, 08:56:39 pmOn the MSO 6000 the 5 digit hardware frequency counter magically becomes 8 digit with ext refProbably same for 7K.5K ?

author: joeqsmith
author_rank: Super Contributor
timestamp: January 07, 2017, 01:22:04 am
content: LeCroy 8500A DSO, 100MHz referenceHP8640B, RF generator 5MHz referenceAll of my HP counters, my old LeCroy 7200 DSO, MARCONI RF generator, HP3589A network analyzer, Sony/Tektronix Arb all have a 10MHz reference.Can't forget the new Signal Hound BB60C spectrum analyzer also has a 10M ref.

author: picitup
author_rank: Regular Contributor
timestamp: January 07, 2017, 09:23:43 am
content: Thanks to all for your contributions.@tautech thanks for the offer of comparing my results. I'll try and remember to remind you.I took a look through the service manual link you supplied for calibrating the SDS1102CML and I can't find a method for calibrating the timebase. It tells you to use a Fluke @10MHz and then calculate the ppm difference and make sure it's within 50ppm, but no method of adjusting it. There is an adjustment section which uses a program called easytest and some tcl scripts, but none of these are for the timebase, just voltage and trigger options.I've emailed Siglent asking them how to calibrate the timebase so see if they reply.CheersSteve

author: deepskyridge
author_rank: Regular Contributor
timestamp: January 07, 2017, 04:10:34 pm
content: Here's a list of the gear in my Lab that accepts a reference input. Some only accept 10 MHZ others accept 1 2 5 or 10 MHZ.HP 5334BHP 8648AHP 33120A - Option 001HP 5386AHP 8642BHP 8591EYes, I like HP Gear.Gary

author: picitup
author_rank: Regular Contributor
timestamp: January 09, 2017, 07:29:21 am
content: Yes I like it to,, but can't afford it lol.I think I've settled on the Siglent SDG1000 series, with 10MHz being the bottom of the shop. These are available in the UK for around £250.00 but I have an AIM/TTI TG120 sig gen and a victor VC3165 (blush) for sale so I might be able to offset some of the cost. I'm sure I could get at least £2.50 for the Victor :-)Hopefully with a couple of sales and maybe a second user SDG1000, I can cobble together enough cash.The spec for the 10MHz ref for the SDG1000 series seems to be a well kept secret, but this guy on YouTube:Says he spoke to his supplier (tequipment.net) who confirmed it is 3.35 vpp. My BG7TBL GPDSO (still waiting...) output is 3.3 vpp and the AIM/TTI TF830 has been proved to work on 1.92v and is specced as ttl levels. So, with the wind behind me, I should be able to connect the GPSDO to both pieces of kit without a distribution amplifier.Anyone have an SDG1010 or better they would like to sell?CheersSteve

author: tautech
author_rank: Super Contributor
timestamp: January 09, 2017, 07:37:17 am
content: Quote from: picitup on January 09, 2017, 07:29:21 amNot really, documentation says TTL levels.Updated, see below.

author: picitup
author_rank: Regular Contributor
timestamp: January 09, 2017, 07:44:56 am
content: Hi @tautech I checked the user guide here:http://www.batronix.com/pdf/Siglent/SDG1000/SDG1000-UserManual.pdfBut couldn't find a spec for the 10MHz ref input. Do you have access to other docs?CheersSteve

author: tautech
author_rank: Super Contributor
timestamp: January 09, 2017, 07:53:38 am
content: SDG1000 Datasheet:http://www.siglentamerica.com/USA_website_2014/Documents/DataSheet/SDG1000_DataSheet_DS02010-E07C.pdfP7, all BNC I/O's listed as TTL compatible.Updated, see below.

author: picitup
author_rank: Regular Contributor
timestamp: January 09, 2017, 08:11:20 am
content: Thanks for the data sheet it's very helpful. Sorry to be really picky, but the data sheet says the 10MHz ref is 5vpp - 5.5vpp and all others are TTL. If this is a typo and the 10MHz is actually TTL levels then I'm still OK as TTL low is <0.8v and high 2-5v so the 3.3vpp of the BG7TBL should be (just) TTL compatible.When I buy one, I'll test the input and see how low it goes.CheersSteve

author: tautech
author_rank: Super Contributor
timestamp: January 09, 2017, 08:37:22 am
content: Quote from: picitup on January 09, 2017, 08:11:20 amNo typo, the datasheet I had on file is an old one without 10 MHz Ref in specs......now updated.What you have now as the current datasheet.Work with 5 Vpp ~ 5.5 Vpp but take note of:Note: The external input voltage can’t be over ±6V, otherwise instrument gets damaged.at the foot of P6.If you drill down in the menus on the Siglent websites much info on models can easily be found.http://www.siglentamerica.com/down.aspx

author: picitup
author_rank: Regular Contributor
timestamp: January 09, 2017, 09:10:02 am
content: Thanks for the info. The link you supplied is really helpful and the data sheet here:http://www.siglentamerica.com/USA_website_2014/Documents/DataSheet/SDG1000X_DataSheet_DS0201X_E01D.pdfHas lots of useful information in it, including a screen shot of the frequency counter which I was scouring the web for.CheersSteve

author: tautech
author_rank: Super Contributor
timestamp: January 09, 2017, 09:32:18 am
content: Quote from: picitup on January 09, 2017, 09:10:02 amHappy to be of some little help Steve.Please be aware the SDG1000 and SDG1000X are 2 quite different series of AWG's, the X series being quite new and has 30 and 60 MHz models only.

author: picitup
author_rank: Regular Contributor
timestamp: January 09, 2017, 04:51:52 pm
content: Thanks for the tip :-) I'm going to put a WTB for the SDG1010 in the Sell/Buy section and see what I can hook out....CheersSteve

author: picitup
author_rank: Regular Contributor
timestamp: January 12, 2017, 01:26:22 pm
content: Well the BG7TBL GPSO arrived. It was a little smaller than I expected but that's fine.Challenge number 1 was to find a US/UK mains adaptor which took me 15 mins lol.I placed the supplied GPS antenna by the window, plugged it into my scope and powered up. Yuk!! the output waveform was a mess. I'm not sure if this is supposed to be square or sine but it's no good so I'll have to get onto the supplier. I tried different BNC leads, different channels on the scope and my bench PSU instead of the supplied one but no change.As it's come all the way from China, I hope they are helpful, but I'll post up when I get a response.CheersSteve

author: DG5SAY
author_rank: Contributor
timestamp: January 12, 2017, 05:52:52 pm
content: Quote from: picitup on January 12, 2017, 01:26:22 pmAre you sure you have a correct 50 Ohms termination? It looks like you have reflections on your BNC. Use 50 Ohm input impedance on your scope.And have a look at this:https://www.eevblog.com/forum/testgear/bg7tbl-gpsdo-master-reference/msg1027377/#msg1027377(you can see the scope is set to 50 Ohms!)

author: tautech
author_rank: Super Contributor
timestamp: January 12, 2017, 06:54:22 pm
content: Quote from: picitup on January 12, 2017, 01:26:22 pmPlace a 5K resistor across its output to mimic the input impedance of the 10 MHz Ref input of a SDG1000 series.The true resistance value it will see will not be 5K @ 10 MHz though but it should give you some better idea if the amplitude and waveform will be OK. That it might look like a sinewave is of little consequence if the input thresholds of the Ref In circuitry are met.

author: picitup
author_rank: Regular Contributor
timestamp: January 13, 2017, 12:49:06 pm
content: What a bonehead. Thanks both for your replies. I have a small tub of 50 ohm terminators somewhere, but can't find them so I hacked a BNC cable and soldered a couple of 100 ohm resistors in parallel to it and voila!Output looks good and works well with my TF830 counter/timer. In fact it works REALLY great. If the gate time is set to 1 second, the output from the OXCO is 10.000000 MHz so the 8 digit display has a resolution of 1Hz, but if you select a 10 second gate, the readout is 0.0000000 MHz with a 'carry' indicator on the display (for the missing 1), giving a resolution of 0.1Hz at 10MHz. That's good enough for me!The GPS antenna is a little finicky, but I don't have a great view of the south from my office, so I just might drill a hole in the wall when no-one's looking :-)CheersSteve

author: picitup
author_rank: Regular Contributor
timestamp: January 13, 2017, 12:51:43 pm
content: Siglent haven't replied yet about calibrating the timebase for the SDS1102CML scope. That 9Hz error is irritating me now..

author: picitup
author_rank: Regular Contributor
timestamp: January 13, 2017, 02:58:13 pm
content: Well it's all set up now and looking good.The GPSDO I have is 2016-05-31. The baud rate is good 'ole 9600,8,N,1 and here are a list of strings it outputs:$GPVTG$GPGGA$GPGSA$GPGSV$GPGSV$GPGSV$GPGLL$GPRMCI'm pleased it does the RMC sentence (time/date) as now I can build that GPS clock I've been hankering after. With that kind of accuracy, I'll be sure to eat my tea on time :-)CheersSteve

author: tautech
author_rank: Super Contributor
timestamp: January 13, 2017, 06:00:21 pm
content: Quote from: picitup on January 13, 2017, 12:51:43 pmThere is significant error in your usage when I look at your screen shot.After some time you will tell us what you have done wrong.As much as I dislike Autoset it can be a good sanity check when things don't seem right, use it.

author: picitup
author_rank: Regular Contributor
timestamp: January 14, 2017, 10:01:41 am
content: OK I've thought about this and can't see what I'm doing wrong. Can you put me out of my misery?I pressed the Auto button and have attached a pic of the result. The one measurement says 10.00MHz but the high resolution one still says 9.99991 Mhz.I know it's always possible I'm being really stupid :-)CheersSteve

author: tautech
author_rank: Super Contributor
timestamp: January 14, 2017, 12:14:24 pm
content: Quote from: picitup on January 14, 2017, 10:01:41 amNot just yet.Examine the timebase settings of these 2 screenshots and explain why the waveform looks the same, but of course it shouldn't be with 2 vastly different timebase settings.Not that one shows a rising trigger setting and the other a falling trigger, no not that.Waveform Aliasing:Autoset.You most likely know the word for this phenomenon but I want to hear from you, then the lesson is learnt and lesson finished.Yep, mean bugger I know.Interesting the frequency counters don't report the same frequency............I have some reports to do on another model of equipment and I'll point Tech support to this one too.Thanks for the screenshot, there's nothing like one to see what's actually going on.

author: picitup
author_rank: Regular Contributor
timestamp: January 14, 2017, 01:29:34 pm
content: C'mon spill the beans :-) I didn't drag you over the coals for adjusting the timebase and the 10MHz ref specs. I just coughed up.I think the two frequencies are the same, just 1 is rounded up and 10.00 is closer to 9.99991 than it is to 9.99. I wonder why it's only 2 digits though?There are some nice NMEA progs here:http://www.visualgps.net/VisualGPSView is nice for setting up your GPS aerial position and NMEATime (Legacy) is quite a nice NMEA clock that will stay always on top and set your PC time to the GPS time. Some of it is free and some is shareware.CheersSteve

author: tautech
author_rank: Super Contributor
timestamp: January 14, 2017, 01:38:11 pm
content: That the frequency counter agrees in both shots is the clue and for the first shot a dead giveaway is that the timebase setting is for nowhere near a 10 MHz frequency.Aliasing.If you've spent some time here reading threads on scopes you will have seen in mentioned for sure.Lesson over.Added edit to reply #43

author: picitup
author_rank: Regular Contributor
timestamp: January 15, 2017, 09:32:03 am
content: Thanks for helping me out in a non-patronising way

author: picitup
author_rank: Regular Contributor
timestamp: January 15, 2017, 09:41:26 am
content: There's quite a good explanation of aliasing here for anyone that's interested:http://www.tek.com/support/faqs/what-aliasing-and-how-do-i-detect-it-and-fix-it-my-oscilloscopeCheersSteve

author: picitup
author_rank: Regular Contributor
timestamp: January 17, 2017, 03:06:08 pm
content: For anyone that's interested, there's a document on the nist web site entitled:The Use of GPS Disciplined Oscillators as Primary Frequency Standards for Calibration and Metrology Laboratoriesand is here:http://tf.nist.gov/general/pdf/2297.pdfThey mention a link to gpstrace which provides satellite accuracy data which is outdated and now is here:https://www.nist.gov/pml/time-and-frequency-division/services/gps-data-archiveI learnt loads from it. Probably should go out more :-)CheersSteve

author: cncjerry
author_rank: Unknown
timestamp: January 17, 2017, 04:42:42 pm
content: Advantest R3131A Spectrum analyzer has 10M input.HP 8568A spectrum analyzer as well. I believe the 8566B does as well, will report back after I go down to the lab to check.

author: picitup
author_rank: Regular Contributor
timestamp: January 18, 2017, 02:23:05 pm
content: @cncjerry thanks for the update. Hopefully this list will be helpful to others.My SDG1025 arrived today, despite the rather long timescales for delivery suggested by the seller which was between 26th Jan and some time in Feb so I'm pleased.I like the SDG1025 which I find very intuitive to use. I found most of the functions just by playing around. I was hoping for the frequency counter to have a higher resolution, but it seems to mostly have 6 digits after the decimal point, offering a resolution of 1Hz at 10Mhz. So I shan't be ditching my TF830 counter/timer which is 10 times better at 0.1Hz. Could be wrong as I'm still figuring the unit out. To access the frequency counter, you press Utility, 1/3, 2/3 and press counter.The 10MHz ref is at the back and to enable it, you press Utility, 1/3, System, 1/2, and CLKSource. It would be nice if the display showed you which clock source it was using. It's a bit of a faff to go through the menus to check. My TF830 displays "Ext" on the LCD which I find helpful. I think I'll pop this into Siglent as a feature request.Anyway, this isn't supposed to be a review of the SDG830 so the interesting bits as far as the 10MHz ref go are as follows:The output of the BG7TBL works fine driving both my TF830 and the SDG1025 directly with no amplification, just a 50 ohm terminator on the end of the chain to stop those reflectionsJust as a sanity check, I connected up the 10MHz to the TF830 and SDG1025 and generated a 10MHz sine wave which was fed back into the TF830. With a 10 second gate time and corresponding 0.1Hz resolution, the display was bang on the money (carry + 0.0000000Mhz) and rock solid so that's a good start.Well after all this messing around with standards, for some reason I really feel the urge to drive my £1.00 quartz clock from the pound shop from the GPSDO. But that's another thread.Thanks for reading and all those that have contributedSteve

author: B1nary
author_rank: Contributor
timestamp: August 30, 2017, 02:52:21 am
content: Quote from: Keysight DanielBogdanoff on January 06, 2017, 07:51:58 pmHaving read through these posts and recognising that my 3104T does not have a external 10mHz reference I wondered if it was even possible to add an external frequency reference to the 3104 or other scopes. More curious than serious.

author: usagi
author_rank: Frequent Contributor
timestamp: August 30, 2017, 04:40:55 am
content: has 10mhz reference input:R&S CMU 200Agilent E7495 seriesAgilent N9342 series

author: edpalmer42
author_rank: Super Contributor
timestamp: August 30, 2017, 05:03:06 am
content: Quote from: B1nary on August 30, 2017, 02:52:21 amIf you're willing to work hard enough, it's probably possible to add an external reference input to almost anything. You'd have to find the appropriate clock inside the unit and then figure out how to get from 10 MHz to the frequency of that clock. Typically, the solution will be a PLL and/or synthesizer. Whether the result is worth the effort will depend on many variables.

author: TheSteve
author_rank: Unknown
timestamp: August 30, 2017, 05:07:10 am
content: Quote from: B1nary on August 30, 2017, 02:52:21 amThe reference in the 3000T series is pretty decent, so there likely isn't too much value in an external reference(if it had it I'd still use it with my 3000T scope though).

author: tautech
author_rank: Super Contributor
timestamp: August 30, 2017, 09:15:59 am
content: Quote from: B1nary on August 30, 2017, 02:52:21 amQuote from: usagi on August 30, 2017, 04:40:55 amPlease.....yes we know you mean Mega not milli but please set an example on an engineering forum by using the correct abbreviations ! !Laziness is no excuse.

author: macboy
author_rank: Super Contributor
timestamp: August 30, 2017, 03:19:01 pm
content: HP 8657B 2GHz Signal Generator has a 10 MHz reference input (also accepts 1 Mhz or 5 MHz). It also has a reference output. The high stability option adds a few inches to the depth of the unit, with an ovenized reference having a separate 10 MHz output which must be externally connected to the main reference input. The main reference output tracks that input and can be used to supply an additional instrument.LeCroy WavePro 960 oscilloscope (2 GHz, 16 GS/s) has 10 MHz reference input.Would be very nice if the OP would maintain a list in the first post. Otherwise, the thread misses it's point.

author: Tony_G
author_rank: Super Contributor
timestamp: August 30, 2017, 03:34:40 pm
content: I love my 8657B - It came with the high stability timebase but I use it on an external 10MHz clock anyway.Personally it seems a bit silly to list all the gear that takes an external 10MHz reference because just about every professional signal generator (now available on the used market) has a reference input - Just in my lab alone I have a 3325B, 3335A, 5351A, 8657B, 8340B, 8673B, 8902A, 8903B, 8563E, 8714C, E4406A, E8285A, 8672A, DG1032A, 53131A and I'm probably missing mentioning some other pieces.That said, the one thing I haven't seen people mention, and it may be of use to the OP, is a distribution amp for the reference signal - A lot of people use old Extron RGB distribution amps (some even modify them down from 75ohm to 50ohm), there are several kits (TAPR TADD-1, etc) - I use a Symmetricom 4036B which I picked up from a Go-Dove auction.TonyG

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: August 30, 2017, 08:14:02 pm
content: Some LeCroy LC series LC3**/LC5**/LC6** and DDA-120/DDA-125 scopes have optional 10MHz reference input.I have DDA-125 with that option.

author: G0HZU
author_rank: Super Contributor
timestamp: August 30, 2017, 10:30:28 pm
content: QuoteWhen wishing to lock high performance RF test gear to a common reference I think it's best to choose a 'master' piece of test gear that has the best internal 10MHz OCXO in terms of noise and stability and use that as a reference to connect all the other gear to.I'm not sure it is always wise to use a GPSDO for this. The extra accuracy will usually be irrelevant and the risk of adding excess noise or spurious terms could be significant. Even if somebody gave me your BG7TBL for free and it was working perfectly I doubt I would ever want to use it as a master reference here for all of my RF test gear because I'd expect it to be too noisy.However, it would be fine for use as a reference for a decent frequency counter if you wanted to check/adjust the reference OCXO in a decent spectrum analyser or sig gen.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 31, 2017, 04:37:08 pm
content: Yes, and even the Dinosaurs of yesteryear TEK 2465B 2467B had options for it...https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg600790/#msg600790

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: August 31, 2017, 04:43:46 pm
content: and what the 10M Ref will do for you...https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg620497/#msg620497

author: Tony_G
author_rank: Super Contributor
timestamp: September 01, 2017, 02:04:24 am
content: Quote from: G0HZU on August 30, 2017, 10:30:28 pmI measured mine and the STDEV of the period is 7.6e-18s and the 20/30MHz harmonics are -70dB down and rest are close to -90dB down. General spurs out to 2 GHz were at least -50dBc.Your mileage may vary.TonyG

author: G0HZU
author_rank: Super Contributor
timestamp: September 02, 2017, 11:34:45 am
content: Quote from: Tony_G on September 01, 2017, 02:04:24 amIt's the impact on close in spurious and phase noise on a (synthesised) high frequency local oscillator that I would be most concerned about.For example, the oldest bit of RF kit on my bench right now is an HP8566B analyser and the first LO typically runs at over 4GHz. So in terms of 20logN that's maybe 53dB wrt 10MHz.So any close in phase noise and spurious on the reference will rise by 52dB at 4GHz. I think the 10MHz OCXO inside the analyser has a phase noise of close to -158dBc/Hz at 1kHz offset. So it's contribution to overall phase noise on a 4.4GHz LO will be 158-52 = -106dBc/Hz at 1kHz. It's probably better than this in reality.But a typical mid range GPDSO OCXO might only achieve -140dBc/Hz at 1kHz meaning the noise contribution will be -88dBc/Hz. The synthesiser loop in my 8566B typically manages to produce a combined divider + reference noise level of about -97dBc/Hz at 1kHz offset (at a 300MHz test freq) so you can see why it's important to have a reference that is maybe 10dB cleaner than this. At a 1kHz offset a 10MHz reference in a mid range GPSDO would be maybe 15dB worse than the OCXO in the 8566B in this respect.The same applies to close in spurious. If there are spurs close to carrier, eg at -100dBc on the reference they can rise by 52dB to look huge on the analyser display at -48dBc on a 4.4GHz local oscillator in the analyser. But a typical 5kHz span on an HP8566B when run from its internal reference will show no close in spurs down to the -80dBc limit on the display where the loop noise dominates at a 30Hz RBW.There seem to be lots of spurs at 1kHz offset in the plot of the GPSDO here:http://www.ke5fx.com/gpscomp.htmI don't know if these spurs are AM or FM or if they are really there or not and maybe this will depend on the quality of the OCXO fitted to the GPSDO and the rest of the PCB layout/design but there's enough there in terms of noise and spurs to put me off wanting to swap the clean OCXO in the 8566B for that GPSDO.

author: Tony_G
author_rank: Super Contributor
timestamp: September 03, 2017, 11:16:25 pm
content: Not disagreeing, just adding some measurements from my unit in case it's helpful for people to understand what you're saying (though it is good enough for my purposes).Here is a phase noise plot - my environment is a bit noisy right now but hopefully it will help:TonyG

author: G0HZU
author_rank: Super Contributor
timestamp: September 06, 2017, 11:54:47 am
content: Thanks.Just to clarify, was that taken of a clean 10MHz test signal with the analyser running its reference externally from the GPSDO?It would be nice to see the GPSDO when fed to something like an E5052A SSA. I have access to these analysers at work but I don't have anything here that can measure the phase noise of a fairly reasonable OCXO. The nearest I have is a Tek analyser. It can just about measure a low cost, low performance crystal oscillator close to carrier but nothing as exotic as an OCXO.

author: Tony_G
author_rank: Super Contributor
timestamp: September 06, 2017, 02:06:37 pm
content: No that was taken with internal OCXO on the unit - Apart from an E4406A which I'm still waiting for a spare part, that is the best I can do here at home.TonyG