Pulse Per Second Dividers, Overdone

Several years ago I designed a little circuit board called the T2-Mini that provides life support for one of Tom Van Baak’s very wonderful picDIV PIC-based frequency dividers. The idea is to convert the 1, 2.5, 5, or 10 MHz output from a frequency standard to a one pulse-per-second (PPS) signal for use in frequency stability measurements. I don’t do things in a small way, so I built a rack enclosure (using the Front Panel Express service to hold 8 […]

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TICC Timestamping Counter

My latest project has turned out to be my most complex (so far…), involving both new-fangled hardware and quite a bit of software, but it’s now finished and working well. Meet the TICC, an Arduino Mega 2560 shield that implements a two channel timestamping counter that has resolution of better than 60 picoseconds (that’s 60 trillionths of a second). TAPR did a production run (we still have them available; go to http://tapr.org/kits_ticc.html) and the units have been in peoples’ hands […]

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FTS-1050A EFC Settings

My FTS-1050A OCXO has thumbwheels to set the EFC, which makes it convenient to use this frequency standard to generate slightly offset frequencies. I measured the frequency with various EFC settings (compared to an HP 5061B-004 Cesium) and these plots show the results for future reference.

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TADD-3 Enclosure

Just finished the second piece of my multiplexed measuring system. This one isn’t too sexy, but is a necessary part — a pulse-per-second (“PPS”) distribution system. This enclosure contains 4 TADD-3 PPS distribution boards. Each board has 2 sets of 3 outputs, plus 2 RS-232 level outputs. So, there are 8 input connectors on the rear, as well as 4 DE9 connectors (the PPS signal is on the DCD line, and I’m only bringing out the RS-232 signal from the […]

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TASS System Multi-board RF Performance

The TASS switch system made a design compromise that means its RF performance has some variation depending on which combination of ports is selected. When using a port that’s not at the far end of the board from the common, there is a transmission line stub of varying length that affects VHF performance. A single TASS board works well through 150 MHz. The question has been what happens when you build a multi-board system? Now that I have the TASS […]

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TASS System enclosure

Several of the design projects I’ve done for TAPR were part of a larger concept I’ve been working on for several years: a measurement system that will allow me to compare the pulse-per-second (PPS) outputs from a bunch of test devices against one of several reference clocks over long time periods (sometimes a year or more). A key part of that system is a “multiplexer” or switch matrix that allows selecting one of several devices under test (DUT) and reference […]

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Pinouts for FTS 1200 9110 1000A-100 1000B OXCO

I rediscovered a post from Corby Dawson with pinouts for the DB9 connector on the above OCXO and wanted to preserve the info here.  Thanks, Corby! 1000B 1000A-100 1200 and 9110 1 EFC ground EFC ground EFC ground 2 EFC +- 10V EFC +- 10V EFC 0 to +10V 3 coarse wiper NC NC 4 +12 pot ref. (10K) NC NC 5 Ground Ground Ground 6 oven mon. oven mon. oven mon. 7 +28V oven +18V oven NC 8 +28V […]

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3 Vintage Sulzers Compared

I did two hour measurement runs of three ’60s vintage Sulzer frequency standards against perhaps the best modern quartz standard available.  These are pretty amazing results.

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TASS Switching System announced, and fun with enclosures

Today TAPR announced availability of a project I’ve been working on for a while, a computer-controlled switch system called the TASS.  It consists of an 8-port relay bank that handles from DC to 150 MHz, a shield for an Arduino, and open source software for the Arduino. You can order the boards from http://tapr.org/kits_tass.html. I also designed an enclosure for a TASS board plus touchscreen controller, and had that built by Front Panel Express.  Here are some pictures of the […]

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Testing a ’60s vintage Sulzer OCXO — with a twist

Over the years I’ve acquired a whole bunch of Sulzer OCXOs.  One is dead, several have oven temperature control problems, but I have three powered up in the rack that still work amazingly well. This one, Sulzer #3, is particularly interesting.  It’s not on the standard 2.5 or 5 MHz frequency.  Instead it runs at 5.006 880 MHz.  That happens to be a submultiple of the Cesium transition frequency.  And I’ve been told, but unfortunately can’t prove, that this unit […]

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