Ultimate 3 QRSS/WSPR TX

boxThe Ultimate 3 QRSS/WSPR transmitter is my first 2015 project, it is a low power propagation beacon, with 180 milliwatt maximum RF output. I purchased the optional extras to make my unit multi-band covering the 40M, 30M, 20M, 17M, 15M, 10M bands. The basic Ultimate 3 WSPR is supplied as a kit that comprises a silkscreen printed main PCB,  pre programmed P.I.C, pre assembled display unit, pre assembled D.D.S board, a low pass filter kit for a frequency of your choice, and a selection of hardware and components. In addition to the basic kit, I purchased the optional metal case, filter relay PCB, five additional low pass filters, and a GPS module.


U3-2-500x340    U3-1-500x340    lpf-U-3-500x340

Above: Pictures of the basic Ultimate 3 WSPR assembled, showing the LCD screen, main control PCB, DDS board, and an assembled low pass filter.

Below: Pictures of the optional extras, the relay PCB that adds five extra bands to the Ultimate 3 WSPR, one of the low pass filter kits that are needed to add the extra bands, and a GPS unit that adds extra functions and better timing to the Ultimate 3.

fil3-U3-500x340lpf2-U3-500x340     GPS-500x340

Assemble of the kit was very straight forward all I needed was a steady hand, a fine tipped soldering iron, a magnifying glass, and a small cross head screwdriver.

I made some minor modifications to my Ultimate 3 to help improve the stability, reduce drift, dim the LCD display and power the GPS module.

First I glued the GPS module to a small piece of Veroboard after removing the copper strips from the back of the Veroboard behind the module. I then soldered wires between the Veroboard and GPS module. I then soldered a 10K ohm pull up resistors between the +VCC – PPC and +VCC – TX. And a 0.1uF capacitor between +VCC – GRD on the Veroboard.

To provide the 3.2 Volts power supply required by the SMK52 GPS module I used two 1N4001 diodes in series with the +VCC to the GPS module, at the RS232 socket.

The GPS module board was then fitted into a GRP waterproof box and connected to the transmitter via two meters of four core screened cable and a RS232 plug.

On the main PCB I added a 330 ohm resistor to the PCB in the optional R2 position to dim the display, and also fitted a toggle switch in the spare hole in the front panel wired in series with the supply to the display so the display can be turned on or off.

After constructing and testing each low pass filter module and the coil on the main PCB, I coated each of the coils with nail varnish prevent movement, this also helps to fix the coils to the PCB’s.

I originally used a SMK52 GPS module (See above), but I upgraded to a SMK61 GPS module as the SMK61 has a  more sensitive receiver, and also works on five volts. The SMK61 needs 4.7k pull up resistors fitted between the PPC and +Vcc, and TX and +Vcc to work properly. It is also recommended that a 47nF decoupling capacitor is fitted between +Vcc and GRD. I fitted all of the components to the Veroboard at the GPS module.

In order to make sure that the GPS supply is as interference free as possible, I also fitted ferrite beads to the +Vcc and the Ground connections of the RS232 socket on the inside of the Ultimate 3 case.

To make the Ultimate 3 compatible with my radio shack power supply, and still keep it portable, I purchased and fitted a variable voltage regulator module based on the LM317 from Ebay. This module allows me to connect the Ultimate 3 to a any AC or DC power supply between 8 and 35 Volts.

Vreg1    Vreg2

The output is very stable, it has an Input range of 6 to 37 Volt AC or DC,  Output range of 1.7 to 37 Volt DC, DC output current of 1A, Ripple rejection ratio of 80dB, Typical load regulation of 0.1%, and Typical linear regulation of 0.01% . These modules are built around the LM317 linear regulator, and are very good value for money.

To reduce the possibility of RF getting in or out of the U3 case via the power cable, I fitted ferrite beads to the +Vcc and Ground cables, in the case close to the power socket terminals.

For portable use, I use an old, regulated, 12 Volt, 1000 milliamp linear power supply,  I found this in my junk box and pressed it back into service. Heavy but goody!!

In the shack I use a Samlex RPS-1202HQ regulated, 2 Amp, linear power supply.

A word of waning:  Do not be temped to use a mobile phone charger or other USB power supply to power your Ultimate 3. USB power supplies / chargers, are usually of the switch mode verity, and will almost certainly cause noise on your signal, and make the frequency of your Ultimate 3 drift badly.

Here are some screen shots of reports I have received during my first month on air with my 180 milliwatt Ultimate 3, using my 40 metre doublet antenna.

30th December 2014

Screenshot from 2014-12-30 09:58:43 Screenshot from 2014-12-30 09:13:03

8th January 2015

Screenshot from 2015-01-08 15:34:24Screenshot from 2015-01-08 15:35:24

13th January 2015

Screenshot from 2015-01-11 17:42:50Screenshot from 2015-01-13 21:51:50

31st January 2015

Screenshot from 2015-01-31 12:31:04    

During the first week of February, I updated the Firmware to version 3.07, my Ultimate 3 now displays the satellite data when not transmitting or calibrating, and also provides PI4 beacon mode, and 8 speeds in Opera mode. Even more for me to experiment with and enjoy!!

Were to get the Ultimate 3 Kit and other parts

To read more about the Ultimate 3 WSPR and other kits by Hans Summers visit his website.
The Ultimate 3 kit, optional extra case, filter kits, relay board kit, or GPS can be purchased from QRP Labs.

Argo – Argo is a program to visually show QRSS, DFCW and other slow digital signals,
into an easily configurable waterfall, taking its input from the PC sound card. I used this software to monitor the TX drift during setting of the HP CAL.

AC/DC to DC Adjustable voltage regulators based around the LM317 are available on the internet auction sites such as Ebay.co.uk for a couple of pounds.

Samlex RPS-1202HQ, 2 Amp, Regulated Power supply, available from Damsu Limited. (Any regulated, DC, power supply rated at 1 Amp or more can be used).

Visit the WSPR website for more information about the WSPR low power project.

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