A new clock plus 10MHz reference GPSDO

M0RVB

I built a thing! This is a GPSDO using a PCB and kit of parts supplied by G8CUL and a OXCO from G1OGY. It uses a Jupiter GPS module which provides the PPS signal and a 10kHz output and the completed module provides 2x 10MHz and 1x 1MHz outputs. Although there are a number of such designs this one is nice in that it also has a display and shows the current date and time as UTC.

A GPSDO system based on a GPS module and OXCO module.

This was, I think my third SMD construction and certainly the Mose SMD devices including multi-legged chips. No issues in construction especially given the quality of the PCB that G8CUL had made.

The display on the GPSDO module showing the number of satellites and quality of signal.

The display on the GPSDO module showing the current date and UTC.

The backup battery is a CR2 3.3V type and helps with warm starting. As the regulator gets hot I managed to fit a heatsink between it and the rear of the case and hopefully this will sort out heat transfer, otherwise I may need to bolt another heatsink on the rear. Construction in a die cast box would have been better maybe but the blue/white box fits in with others in the shack, plus I had it already! The bezel is cut down from a 3D printed one from Printables.com designed specifically for the 2x16 LCD displays. The button - which is not the best but I had one etc. - selects the various displays which include date and time, satellites seen, latitude, longitude, altitude and QRA locator.

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M0RVB

"A man with two clocks..."

You know the saying, a man with a watch knows the time but a man with two watches has no clue. Well, my GPS clock plus 10MHz source has decided it no longer wants to be a clock. It was a nice idea, came as a kit of parts from three sources and worked well up to a point. But the GPS module always seemed a little deaf. I had it connected to one of those little magnetic pucks but it struggled, often loosing all sight of any satellites. I tried it on an external antenna (sat on the windowsill) and on the puck placed outside with no difference. With a splitter inline a Leo Bodnar unit was happy so I had to assume the antenna was fine. Anyway, it has spent all day with no satellites in view whereas the QRP Labs clock is fine as is the NPT server. So it has been switched off and assigned to the 'box of abandoned projects' where it resides, alone. (edit: that one is now outside in the workshop with a small GPS antenna on the workshop roof and is working just fine - except the LCD is very sluggish with…

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M0RVB

Clock

I finally have a UTC clock (it does other stuff too). This is a QRP Labs Clock built from a kit of parts plus a GPS receiver, also QRP Labs. Very simple to build. It runs from 5V (pity it's not 12V but there you are) but I recently acquired a 5V linear PSU to run the three little LoRa boards rather than the 12V/USB charger I currently use. The kit is not yet finished - I need to attach the power switch and connect those two push buttons - but it's a neat little thing in a nice case. I was looking for a GPS locked UTC clock and recently built a kit which is also a 10MHz source and has a 10MHz OCXO to make a really useful device. That also has a clock display as well as other dispel modes such as satellites, locator and such but the clock is always about 1 second slow. Reading through the documentation from QRP Labs it transpires that this is because the 1PPS signal and the NMEA data can overlap, so the data stream from the GPS that shows date and time is not aligned to the PPS pulse which…

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M0RVB

10MHz OXCO

I recently acquired a 10Ghz / 144MHz transverter which should get me a little closer to the band. I do still have a kit to build but having this means I can eventually test that as well. It needs a 10MHz reference input and I was recommended one from an eBay seller in China. The unit arrived today and having had it sat on a 'scope and counter for several hours it does seem to produce a solid 10Mhz signal at a nice sine wave (it has TTL output too). Not bad for £12.

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