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This clock kit is based on the same hardware as Ultimate3/3S QRSS/WSPR kit and a special firmware version. A GPS receiver module such as the QLG1 can optionally be connected for precision time-keeping. The display format is customisable; as well as time and date, you can also choose to display GPS data (e.g. location, number of received satellites, etc).

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This is a shack clock kit which can optionally also be connected to a GPS receiver module such as the QLG1 to provide precise time. Alternatively it can be used standalone or with a different 1 pulse per second (pps) signal source.

The clock can be configured to display time, date, and various information decoded from the GPS serial data stream. Two Analogue temperature sensors an optionally be connected to the kit, so that temperature measurements can be displayed (for example, indoor and outdoor temperature). The contents of the display are configurable. The photographs on this page show the default configuration of the clock display.


These are the instructions for the latest PCB revision and Firmware version. Please check your PCB and your firmware revision. If you have an earlier version use the correct documents in the next section.

Assembly manual (PCB "QCU Rev 1" or "QCU Rev 3")
Operation manual (firmware c1.01 and c1.01a)

Documents: older PCB and Firmware versions

Assembly manual (PCB "U3S Rev. 2", old U3S PCB)
Assembly manual (PCB "Rev. 5", old U3 PCB)
Operation manual (firmware c1.01 and c1.01a)



Firmware version history

Version Date Features
c1.00 08.Apr.2015 - Original kit firmware version
c1.01 31.Aug.2015 - Support for 4 x 20 LCD.
- Local Time Offset entry, in minutes.
- #LH and #LM tags for local time hours and local time minutes.
- #H2, #AP tags for local time hours in 12-hour format, and "AM"/"PM" display.
- Added alarm function: Alarm, AlarmOn params. To cancel Alarm, press Right button.
- Bug fix: Factory reset copied 2nd display line on 1st, and did not reset second display line
- Bug fix: Factory reset put temperature calibration values to non-Factory values.
- Bug fix: If GPS latitude/longitude displayed on top row, it could cause some display corruption of row 2 in some cases.
- Bug fix: Long message strings, overwrite the top LCD line when looping through menu.
c1.01a 01-Dec-2015 - Just a recompilation under latest AVR Studio on Win 10. No new functionality or changes!

4-line display

The clock firmware from firmware version c1.01 onwards supports a 4-row 20-column LCD. Each line can be configured, just the same way as the standard 16 x 2 LCD module supplied in the kit. The following photograph shows a 4-line clock display by Bob ZL1RS.

4-line display

Beautiful customised build by Henk PE4H

The photographs below show Henk PE4H beautifully made clock. Like Bob ZL1RS above, Henk also uses a 4-line display. His enclosure includes power supply and QRP Labs QLG1 GPS. A unique step by Henk, was to incorporate lower case characters into the display. The configuration of the clock supports upper case characters only. But Henk read out the EEPROM .eep file, and edited it in AVR Studio 7's hex editor, replacing the desired upper case characters with lower case ones.

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Very nice shack clock built by Ed WA4MZS

Ed sent me some photographs of his project (click thumbnail pictures below) and writes:

"The case / cabinet is a Bud PC-11406. Front panel was painted with Rustoleum 'Charcoal Gray' (a close match to the Collins front panels). No lettering, as operation is simple, and at my stage of life, applying dry transfer lettering and getting it straight is a real challenge. The bezel around the display was necessary, as I can't cut a neat looking rectangular hole either (same reason as above). Rough cut the hole, then glued in the bezel, made from 1/8" (3mm) plastic angle stock from the hobby shop. All said, I'm real pleased with how it turned out!"

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Clock kit with temperature sensors, by Gareth G4XAT

Gareth fitted indoor and outdoor temperature sensors and had difficulty with the long wire to the external one. The solution may be useful to other constructors. Gareth writes:

"I’ve finally built and cased the shack clock kit I bought a while back. Very nice it is too…..
I decided to add internal and external temperature for my shack re-fit. On short wires they both worked fine. With one on LONG wires, I was getting –ve numbers?? Strange I thought, so I ordered another sensor. SAME problem. SO I had a look at the data sheet page 10 where it recommends a 0.1 across the pins. Problem solved. There is still a bit of ‘jitter’ – I’m wondering if another small cap on the input pin would help with that. Although it’s a 10 bit A-to D, 10 mV is naff all, so some smoothing might help. Or software smoothing by multiple averaging, but I guess you might know about that ;-)
Picture shows my two solutions, one inside the 3.5mm stereo jack plug, on at the end of the outside wire prior to a blob of epoxy sealing it forever."

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