DIY HP/Agilent 53131A 010 High Stability Timebase Option

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Having obtained a reasonably reliable 10Mhz lab reference I decided to calibrate my Frequency Counter only to find that the stock oscillator provided in the HP 53151A is absolutely terrible - a joke even! I looked around for an "010 High Stability Timebase Option" but they are rare -- and if you can find one not installed in a counter they are very expensive - in the few hundred dollars range at least -- and buying one from HP is, well, expensive in the extreme. There are many second-hand 10MHz OCXO modules available, these are mostly stripped from old telecommunications, satellite or cellular equipment so they are plentiful and relatively cheap to buy too. I decided to make a clone 010 option board for my counter using a second-hand OCXO bought from e-bay. I designed a PCB to get a professional finish as well as a reliable upgrade for my counter. The main goal was to make an option board that just like the original could be automatically calibrated using the internal software and front panel controls so I had to use the same DAC chip (which is now obsolete) and basic topology of the original option board to make it work.

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25 авг 2013

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Комментарии : 48

@Narwaro 7 лет назад

It is purely gravitation. The crystal does actually have a mass (although it is very small) and changing the orientation does change the characteristics of the oscillation because the direction of the force changed. Although only having a very small impact, it comes to light when doing measurements in the order of 10^-10 like this.

@tedfrisk4730 5 лет назад

You're absolutely right Sir.

@JoeTufts 8 лет назад

The gravity effect is very cool. Nice find.

@gerrysweeney 10 лет назад

Thanks, it was a nice mod to make, pretty easy and painless. Just building the second board now using the Datum OCXO, I will see how that goes. Gerry

@gerrysweeney 10 лет назад

I used DipTrace to create the boards, I don't really like Eagle myself, to unintuitive. The prototype boards cost about $80 for 5 off. Glad you like the videos and thank you for the comments. Gerry

@gerrysweeney 10 лет назад

The OCXO I used is up to working spec from the best I can tell within about 12 minutes. For a calibration lab, perhaps a brand new one but these second hand OCXO's could even be better than new because they have had burn0in time and of course aging too. None the less, you are right that a company would probably buy an OCXO new but for a home lab this is a darn good mod as far as I am concerned :) Its a massive improvement on the stock timebase, thats for sure.

@gerrysweeney 10 лет назад

Thanks for the feedback. Gerry

@pdpate3 6 лет назад

Truly inspiring! Thanks Mate!!!

@gerrysweeney 10 лет назад

Hi Andrew, yeah could be, I had not thought of that. However, the effect is pretty instantaneous, I would have expected some thermal lag. Not sure but thanks for the comment. Gerry

@gerrysweeney 10 лет назад

Thanks John

@gerrysweeney 10 лет назад

Sure I can, but its still nice to have the counter work stand-alone, you never know when it would be useful. Or if I sold it, it would be a great counter even without the Rb standard. I like things to be complete and as good as they can be. Gerry

@gerrysweeney 10 лет назад

Hi Ian, Thanks for the pointer, I guessed it might be gravity.... Gerry

@pcrengnr1 8 лет назад

Gerry thx for video. Great that you got an autocabrating option for your counter for a low lost with some effort. Since Cern has enhanced it KiCAD is a great schematic/PCB EDA software. It it well supported across the world and the libraries grow and grow. That data files are human readable ie not proprietary. The best part is that it is free

@gerrysweeney 8 лет назад

+pcrengnr1 yeah I had a look at KiCad again (looked at it three years ago), it is definitely a lot better than the last time a looked at it. I might have a go at a small project using it and see how I get on with it. Thanks for your comments

@SeanBZA 10 лет назад

I would guess it is the changing stress on the crystal mounting points as you rotate it. These then change the stress applied to the crystal which change the frequency slightly. You will have a similar change with pressure, so it will be slightly out at altitude compared to a sea level location.

@gerrysweeney 10 лет назад

Hi, The Rb reference does not have the same problem. There is a link to a document in the comments below that explains it, its basically gravity taking effect on the crystal blank in the OCXO. Gerry

@SylwerDragon 10 лет назад

Really helpful video. I do watch your videos and they are really interesting. :) Btw It is simple reason why they don't put really good OXCO inside those counters. First you would have to wait at least 1 hour. and next price of oxco is about 200 Euro. I did try to order one( :) ) . new one are really expensive. used like yours are cheap. But if company wants reliable equipment that will be stable they'll buy new oxco or better equipment. But for us it doesn't matter :).

@dellmyer 10 лет назад

What software package do you use to layout the board? Do you use Eagle? I use eagle but it's ok... Also how much did it cost to get the boards made? Great video's... Dan

@michaelpilliod1039 6 лет назад

I built one and the results are amazing. I used the osciloquartz and 3 years later it's in near perfect calibration.9,999,999.99. I'm not entirely sure that the rubidium reference is good enough to call that off by anything . As he said the base model internal clock is essentially worthless.

@supernova86 7 лет назад

If you want to get a more accurate measurement, set your counter's gate time to atleast 1 second, you will get another digit of resolution. You can also run stats to average multiple measurements. I would also set your counter's input impedance to 50 ohms if you're going to have that 50 ohm load in parallel.

@gerrysweeney 10 лет назад

Hi John, The only option it has written on the back is "55", the oscillator looks like a TCXO though, I was just looking at the intermittent fault - which looks like its going to be hard to find :( Gerry

@aptsys 9 лет назад

The AD7243 seems freely available. Did they put it back into production or did they change the specs?

@gerrysweeney 10 лет назад

Thanks :)

@IanScottJohnston 10 лет назад

Gerry, found this on the web...."Orientation Sensitivity (tip-over). When the physical orientation of an oscillator is changed, there is a small frequency change (typically not more than several parts in 10-9 for any 90 degree rotation), due to the change in stress on the crystal blank resulting from the gravitational affect upon the crystal supports". See - vectron. c o m/products/literature_library/ocxo.pdf

@KX36 10 лет назад

Fair enough. :) Good video.

@AndrewBasterfield 10 лет назад

Maybe the change in frequency w.r.t. orientation is a thermal effect; i.e. hot air rises?

@gerrysweeney 10 лет назад

It would appear to be gravity, see a comment above, there is a link to a document that explains it. Amazing I have something accurate enough to measure it :)

@KX36 10 лет назад

cant you just use the Rb standard as your reference if they're always both on the same bench? wouldn't that be better than even an OCXO

@alperenalperen2458 7 лет назад

Can't you just connect your rubidium standart to the external refrence of 53131A?

@tabajaralabs 3 года назад

hey Gerry, will you make gerbers vaiable? thanks a lot! :)

@gerrysweeney2127 3 года назад

Hello Alex, I have not made the Gerbers available, but I do sell the bare PCB's which helps pay for some of the effort and equipment that goes into making vids like this. If you want a PCB or two you can order them via PayPal links on this blog article. gerrysweeney.com/update-diy-hpagilent-53131a-010-high-stability-timebase-option-pcbs-available/

@tabajaralabs 3 года назад

@@gerrysweeney2127 Done! I asked before I believe I believed I clicked on the link before and it said it wasn't avaiable... Thanks a lot, and greetings from Brazil =)

@gerrysweeney 3 года назад

@@tabajaralabs thank you for your support, will get out in the post tomorrow.

@THEMATRIXVIDEO 3 года назад

GERRY, WHAT'S THE BEST 53131A OR 53181A? I HAVE 2 BUT I WANT TO SELL 1, THANK YOU

@gerrysweeney2127 3 года назад

They are both the same except I believe the 131A has 2 or 3 channels, the 181A has 1 or two channels. There might be other differences but I have never actually seen a 181A in the flesh, I have only ever come across the 131A's

@THEMATRIXVIDEO 3 года назад

@@gerrysweeney2127 THANK YOU FOR YOUR ATTENTION GERRY, CONGRATULATIONS FOR THE VERY EDUCATIONAL CHANNEL

@gerrysweeney2127 3 года назад

@@THEMATRIXVIDEO your welcome, thank you for the feedback

@FranklinLaserBlog 9 лет назад

That's a gravity effect.

@n8ibz1 2 года назад

Are you still selling this boards, populated or not, I did order all the parts to populate the board then realized you my not sell them anymore? Silly me!

@gerrysweeney 2 года назад

Hi Mark, yes still sell the boards, bare and fully built. PayPal links on here: gerrysweeney.com/tag/53131a/ thanks, Gerry

@n8ibz1 2 года назад

Fantastic, thank you very much....

@n8ibz1 2 года назад

sweet boards, thanks for all your support....much appreciated. 73 Mark Adams N8IBZ

@n8ibz1 2 года назад

Gerry, quick question. with the ISOTEMP OCXO 131-40 10MHz 12V Sine Wave 36X27X17mm Crystal Oscillator work in place of the 100 or 199? Thank you.

@gerrysweeney 2 года назад

@@n8ibz1 I have never tried that version of the OCXO, but so long as the pinout is correct I would expect it to work without issue. Gerry

@quadplay2591 5 лет назад

Thanks for this video. Just one point which you may not realise. You talk with your hands a lot which is normal. But as a result when show a device to the camera it jiggles about a LOT and is very distracting. It is better to show the device or PCB us a separate steady shot. You will find this far more professional video wise.

@gerrysweeney 5 лет назад

Indeed, I do and I need to keep thinks more anchored in future. Thanks for the feedback. Gerry