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Ultimate3S: QRP Labs Multi-mode QRSS Beacon Kit
1. Introduction
Thank you for purchasing the QRP Labs third generation "Ultimate3S" Multi-mode QRSS beacon kit. This
kit is capable of automated transmission of a range of weak signal modes that are capable of worldwide
HF propagation using a fraction of a watt of RF output power. The Si5351A synthesiser module permits
accurate, stable operation anywhere on LF/MF/HF/VHF whilst plug-in low-pass-filter modules allow easy
band changing.
Recommended approach to building the kit: This is a simple design but there are a large number of
features which provide a great deal of flexibility. Read this WHOLE manual and understand it! Follow
the construction section to build the kit. Use a receiver connected to your PC, with a slow-signal decoding
program such as Argo. Monitor your signal, experiment and understand the various features before
connecting an antenna! Good performance depends on proper set up: see the calibration section.
This assembly manual must be read in conjunction with the operation manual!
The U3S kit supports the following modes:
QRSS mode (plain on/off keyed slow CW)
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FSK/CW mode (frequency shift keyed slow CW)
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DFCW mode (dual frequency CW, dit's and dah's on different frequencies)
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WSPR and WSPR-15 modes (Weak Signal Propagation Reporter)
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Slow-Hellschreiber (frequency shifted slow Hellschreiber)
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Hellshreiber (full-speed standard Hellschreiber, and half-speed Hellshreiber)
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CW (plain CW) and fast FSK mode
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Transmitter mode (manual keyed, on/off CW or FSK)
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Customisable FSK patterns
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Opera
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PI4
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Other features:
Si5351A synthesiser controlled output frequency (kit included with the U3S)
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Plug-in low pass filter boards (for all LF/MF/HF bands from 2200m to 10m, plus 6m band)
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16-column x 2-row LCD with backlight, and two-button user interface
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User-programmable (callsign, message, speed, FSK, mode, etc.), settings stored in EEPROM
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GPS interface, for locking the frequency, timing and location information
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On-chip generation of WSPR encoded message (no PC required)
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WSPR maidenhead locator can be generated from GPS-derived latitude/longitude
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Selectable "frame" size, for stacked QRSS reception
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Plain CW callsign identifier at selectable interval
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Produces approximately 250mW RF output on 30m (lower output on higher frequency bands)
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Higher output power by fitting additional PA transistors and/or higher PA supply voltage
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PCB Revision 1
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Summary of Contents for QRP Labs Ultimate3S
- Page 1 PCB Revision 1 1. Introduction Thank you for purchasing the QRP Labs third generation “Ultimate3S” Multi-mode QRSS beacon kit. This kit is capable of automated transmission of a range of weak signal modes that are capable of worldwide HF propagation using a fraction of a watt of RF output power. The Si5351A synthesiser module permits accurate, stable operation anywhere on LF/MF/HF/VHF whilst plug-in low-pass-filter modules allow easy band changing.
- Page 2 The transmitter is designed to be powered with 5V DC. This could come from a mobile phone charger, wall wart, or even four 1.5V batteries connected in series with a suitable low dropout regulator. However not all chargers and wall warts are clean enough for powering the microcontroller. Do not use more than 6V: this may kill the microcontroller;...
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Page 3: Parts List
2. Design The ATmega328 AVR microcontroller (IC1) is pre-programmed with firmware to control the LCD, buttons, and GPS interface. The Si5351A Synthesiser module kit includes its own on-board 27MHz crystal reference oscillator. On/off keying is handled in software by switching on/off the output stage of the Si5351A synthesiser IC. - Page 4 4. Construction 4.1 General construction tips The kit comes as a main board, plug-in Si5351A synthesiser module, and a plug-in low-pass-filter module for the desired band. The Si5351A synthesiser module and low-pass filter module are separate kits. The synthesiser and one LPF are included with the U3S. Please refer to the separate instructions for constructing these kits.
- Page 5 1) Solder in the socket for IC1. To avoid confusion or mistakes later, align the dimple at one end of the socket, with the dimple illustrated on the PCB. The dimple should be at the end nearest the right-hand edge of the PCB. 2) Solder in all capacitors and the quartz crystal (note there is no C7).
- Page 6 6) Fit and solder R1, the preset potentiometer that sets the LCD contrast. Be careful not to mix up the presets R1 (100K) and R5 (4.7K)! The code on R1 is “104”. It is a slightly tight fit but apply pressure carefully and evenly, and the pins of the potentiometer will fit into the PCB perfectly.
- Page 7 The "Heat" connection should be connected to +5V also, if you are using the OCXO version of the Si5351A module. It provides +5V to the oven heater, using a thick track on the PCB. This avoids voltage drop on narrow traces. If you are using the non-OCXO version of the Si5351A synthesiser module, then you do not need to connect the "Heat"...
- Page 8 Be sure to solder the socket to the reverse of the main U3S PCB!! Not the top side! it is very hard to fix later, if you get this wrong! Bolt together the LCD module and the PCB, with the 16-way connectors in place but not soldered.
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Page 9: Hardware Options
Then you should see the flash screen. If the Si5351A module is correctly built and inserted, the firmware will recognise it. The text in the splash screen will say "Ultimate3S". The "S" is important, it signifies that the Si5351A has been correctly detected. - Page 10 S1 signal and ground; similarly the right button should be connected between the S2 signal and ground. Suitable buttons are supplied in the official QRP Labs U3 Case and accessories kit. 4.4 Optional connection of GPS module...
- Page 11 For example, you could switch the display on to set up the kit, then leave it switched off during operation. The official QRP Labs U3 Case and accessories kit includes a spare switch which could be used for this purpose.
- Page 12 4.8 In-circuit programming of AVR If you own an AVR programmer, you can make connections to the U3S to allow updating the firmware without removing the AVR chip. In this case, you should fit a 100K resistor as R3, not a jumper link. This is shown enclosed in RED on the right side of the below diagram.
- Page 13 5. Calibration This section is REALLY IMPORTANT! It is very important to realise that by far the hardest part of any successful QRSS beacon operation, is tuning the oscillator to the correct frequency. For example, most 30m QRSS stations monitor a narrow 100Hz-wide band from 10,140,000 to 10,140,100. If you are much outside this, the chances are that nobody will see your signal.
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Page 14: Version History
8. Version History 14-Jan-2015 First version • 26-Jan-2015 Correction to section 2, Design. Removed incorrect reference to DDS module and keying transistor • 03-Feb-2015 Correction to R5 value, the supplied trimmer is 4.7K (not 5K as previously stated) •...