10MHz reference source

[Jared]

Hi,

I am having a look at making/buying/getting a 10MHz reference source and am looking at a few GPSDO (GPS disciplined oscillator, for those that dont know).

Justin, do you know of a good one, that is relatively inexpensive?
I’ve send enquiries off to Trimble, Microsemi and a few others. I see there are some relatively cheap units on ebay too…

Anyone used/using one they can recommend?

Cheers,
Jared

[Jared]

Update:
So the retail price of a entry-level commercial GPSDO starts at around 600USD, which with currency conversion, freight and local taxes is way more than I want to spend on it.
The ebay ones, upon a lot of internet reading, seem to actually be quite good, so I have one of those on its way.

It outputs ~+13dBm and has a sinewave output.
I expect that is a little too much for the input on the SA44B (it’s at home so I cannot look at its back)?
Also does this prefer a sine or square signal?

[Justin Crooks]

+13 dBm reference is fine for the SA44B (it will tolerate up to about +20 dBm). The circuitry prefers square for lower phase noise, but +13 dBm has a pretty fast slew rate, so it probably doesn’t matter much.

If frequency doesn’t have to be exact (+/- 0.1 ppb typical), you might be able to find a used LPRO Rubidium standard for $150 or so.

[Jared]

Cheers Justin, I had a look for a Rb standard, but nothing available at the time. I found a nice LT part to convert sine to square and not add too much phase noise (-103@100hz). You may want to add some detail info in the documentation for this input…
Thanks for clarifying!
Jared

[Tishers]

I have a Rb standard that I use for other pieces of test equipment. The Efratom ones are pretty good. It was an ebay purchase a few years ago, affordable enough that I bought a spare a few months later.

[Jared]

Cheers guys.
My ebay one turned up and once I repositioned the GPS antenna to the window sill it locked in pretty quickly.
I’ve got a couple of NDK oscillators as samples (DOXCO/OXCO) so I’ll make up a board to run them and then see how it looks compared to a 3ppb OCXO.
I’ll keep an eye on ebay for a rubidium standard as well.

[Tishers]

If you maintain a decent test bench and go the route of getting a Rb reference you will eventually find reasons to attach all sorts of 10 MHz devices to it. I use it on counters, scopes, frequency selective voltmeters and other analyzers.

I leave the Rb reference running all the time. It is even attached to a 24 VDC battery to keep it going during power glitches. With some additional devices I can do much of my own metrology and calibrate my own gear.

Tisha Hayes

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