[time-nuts] Inexpensive Alternative to a 5120A

Cube Central cubecentral at gmail.com
Fri Oct 7 14:32:54 EDT 2016

Thanks Bob, I hope your cold improves, and I thank you for that answer.  

As I happen to have a HP 5335A and I think it has the options 10 and 30.  So from there, you are saying that the next step would be a GPIB adapter.  Here be dragons, as I have never used anything with GPIB before.  I am happy to order one today if you (or someone) could point to exactly the one I should get (perhaps an e-bay link?) or are all these pretty much standard?

I also have a very nice GPSDO thanks to Nick Sayer's project:  https://hackaday.io/project/6872-gps-disciplined-xcxo

I assume that things will become clear the more I research GPIB and adapters?  I think that is the missing piece I was looking for in order to really use the Timelab software.

Thanks again for the help, all you time-nuts, as I seem to be ready to take the next step...

    -Randal R.
        (at CubeCentral)

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob Stewart
Sent: Friday, 07 October, 2016 11:21
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Subject: Re: [time-nuts] Inexpensive Alternative to a 5120A

Hi Randal,
I've got a bad cold, so I can only hope this response is rational.
To begin with, you need some sort of Time Interval Counter (TIC), as well as some way to get the measurements from it into your computer.  Once you get that, then you get a free copy of John Miles' indispensable Timelab software and have at it.
A beginner setup might consist of an HP 5335A, which can be found cheaply, and a GPIB adapter.  Be sure to get a 5335A with the high stability OCXO; i.e. the venerable HP 10811.  You can find both on ebay, but the usual cautions apply.  Personally, I prefer the Prologix Ethernet GPIB adapter.  It's pricey at about $200, but it's the easiest for mere mortals to interface to with custom programs that you may be tempted to write.
If you want to get a bit better than that, then you'll probably go with an HP 5370A with a 10811.  Other companies make good TICs, as well.  At some point you'll probably want to get a better standard than the 10811 in your counter, so you'll consider either a Rubidium standard or a Cesium standard.  Personally, I'd avoid the FE-5680s on ebay, as they're not as stable as you'd expect them to be.  But, other people may disagree.  Cesium standards aren't cheap - unless you happen to make the score of a lifetime as another time-nut did with a PRS-45A.
You can also use a GPSDO as a reference.  I sell a new one, and you can find good surplus units on ebay at various prices.  Different GPSDOs will have different qualities.  They all suffer from to extent from ionospheric drift.  Older units with older receivers probably have the most, but I'm not an expert on GPSDO selection.
So, with all that said, start with the cheapest you can afford, and then decide whether you really want to get into serious time-nuttery.  It's not an inexpensive hobby, even at the low end.  But it's probably cheaper than a diet of loose women and beer!

Bob - AE6RV


      From: Cube Central <cubecentral at gmail.com>
 To: 'Discussion of precise time and frequency measurement' <time-nuts at febo.com>
 Sent: Friday, October 7, 2016 11:52 AM
 Subject: [time-nuts] Inexpensive Alternative to a 5120A
I saw that someone was using one of these: http://www.microsemi.com/products/timing-synchronization-systems/test-measurement/test-sets/5120a

...and the more I looked at it, the more I wanted one.  However, I couldn't get a price for one, but only quotes.  This can only mean that they are really expensive and out of reach of mere mortal novice time-nut like myself.

Is there an alternative that someone could point me to that would cost only a couple hundred rather than (what I expect) is a couple thousand?  How would I go about gathering the data needed for these nifty ADEV graphs I see floating about in here?

Could there be a kit or something that I can plug into a PC?  I really don't even know where to start looking?

Thanks - in advance - for any suggestions!

    -Randal R.
        (at CubeCentral)

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