The QRP Labs QRSS Beacon Kit is available in 3 versions, 80, 40 or 30 metres and costs £10.00 plus postage. This is a quick and easy way to get on air and will not break the bank. There are only 30 components in the kit and the placement of these is determined by the legend on the printed on the board. At the most it should only take one hour to build the project. The transmitter is designed to be powered with 5-6 V DC which could come from a phone charger, 4 x 1.5V batteries in series or a USB power supply from the computer. There are of course many other kits available.
The transmitter consists of a simple Colpitts Oscillator, a buffer stage, and Power Amplifier followed by a 7 element Low pass filter. The Atmel micro-controller is pre-programmed with the desired callsign and keys the transmitter. The keyer shifts the oscillator frequency by a few Hz via a red LED which behaves as a varactor diode. It should be noted that the LED does not light up during the keying cycle. The transmitter will produce 100 – 150mW of continuously keyed FSK CW the key down is 5Hz higher than key up.
After the construction of the board is completed it is just a case of connecting up a dummy load to the output of the P.A. and applying power to 
set the appropriate drive level. If the drive level is set incorrectly, the power will reduce and the output device will get noticeably hot.
It is important to fine tune the FSK CW with the “gimmick” capacitor, made with two strands of wire twisted together, so that the difference between mark and space is no more than 4-5Hz. Twisting the wires of the gimmick capacitor together more will increase the shift or unwinding will decrease the shift. Too much shift is unnecessary and only uses too much band space. All that remains is to connect to the desired antenna.
The transmitter will be stable if placed in a metal box of some description and protected from extremes of temperature. A small piece of expanded polystyrene around the crystal will also help ensure temperature stability.
After completion, the project was installed in an Altoids tins (what QRP project isn’t) and connected to the dummy load and power applied. A good 
trace was seen on the scope and the output was tuned for maximum power output that, in this case, was 140mW running into a dummy load. A speed of 6 second dits was selected and this was received on the station tranceiver. A connection to the computer was established via the TigerTronics interface and, with the ARGO software running, the gimmick capacitor was trimmed to produce a mark space frequency difference of 5Hz (see Fig 3). Whilst this was being done the power output was turned down to almost zero so as not to overload the receiver.
Results:
The QRSS transmitter was connected to an inverted L tuned by an SGC tuner although pre-tuned in this case and the TX power was applied. Using the online Grabber from ON5EX, which generally produces visible results at most times of the day, nothing was received! As the evening wore on there was a faint trace but barely readable. This was not consistent with results one would expect so another check on the transmitter was performed.
The power had been turned down whilst the mark space frequency was being set and not turned back up again. In this case there were barely microwatts being transmitted. A quick re-tweak of the drive level and there were now 140mW transmitted. The effect was instantaneous. Three Grabbers in Europe were now receiving a strong signal. The signal was stable and remained on frequency for well over 4 hours before being turned off for the night. Fig. 4 shows the EI5DD signal as received by the ON5EX grabber in Belgium at 11pm on the 40 metre band on 7.000790 Mhz. As can be seen there are many other signals occupying the band.
The results obtained were quite remarkable considering the antenna is less than satisfactory due to the short length of the back garden. After setting the frequency, there was a short period where the transmitter frequency stabilised after closing the lid of the Altoids tin. It should be noted that when the lid was closed the frequency dropped 30Hz L.F. which is quite a lot on QRSS. With this in mind and a little trial and error the transmitter was finely tuned to a clear frequency. Probably the most impressive part of the exercise was the fact that, with the drive level at almost zero, the signal still managed to register on the grabber in Belgium. The stability of this transmitter was also quite impressive although if there were extremes of temperature in the shack slight drift may become apparent.
Reception of QRSS
For Reception of QRSS signals it is essential to utilise a stable receiver. Many signals of 5Hz bandwidth will be received in a window of 100Hz width. A receiver that is prone to drift will probably loose the entire window in the process of warming up. It is necessary to turn off the AGC as the QRSS signal is probably barely above the noise floor of the receiver and signals within the AF and IF pass band will cause the AGC to reduce the receiver gain. Another undesirable trait of some receivers is the effect of inter-modulation distortion within the audio stages of the receiver. Whilst not that noticeable under normal operation, these IMD effects can result in a ghosting effect on received signals. Since QRSS sub-bands are generally no more than 100Hz wide it is quite acceptable to reduce the receiver bandwidth to between 300 – 500 Hz.
Antennas for QRSS transmission and reception are very much dependant on the area in which they can be erected. A resonant loop antenna will always give excellent results and also low band noise. Broadband active loop antennas tend to increase IMD effects at the receiver due to the high strength of signals that are far removed from the frequency of interest.
Propagation anomalies.
As the reception of a QRSS signal is from a visual display it is possible to see any anomaly of propagation as it happens. A couple of examples illustrate some dramatic effects.
This grab shows the reception of a UK QRSS signal by GJ7RWT. The time of sunrise was 6.52 am and within 2 minutes the received signal disappeared as if a switch had been thrown. This illustrates just how quickly the level of D-Layer ionisation can build at sunrise completely absorbing the signals from the UK station.
This grab shows the reception of signals on 10 MHz. A Doppler shift in the signals occurred prior to a complete fadeout. ( note the signal trace appears to skew higher in frequency suggesting a rapid descent of the ionisation layer). This phenomena was reported on a worldwide basis. Each station had a similar report and picture of the event.
This shows multipath distortion following a solar event. Especially noticeable is the multiple traces on the signals at the upper and lower portions of the display.
Many of these phenomena such as Doppler shifts would probably not be experienced audibly due to the fact that the frequency shifts are only a matter of a few Hz.
By posting your information and contact details on the Knights QRSS clipboard it will be possible to receive e-mail reports on your signal. This is an interesting site as it lists QRSS transmitters and also those who have set up grabbers for receiving QRSS signals. The url for this location is http://www.on5ex.be/clipboard_view_unreg.php
QRSS frequencies.
137.6 – 137.8
18432
3.500, 3.575, 3.579, 3.5999
7.000, 7.042, 7.0599
10.140
14.000, 14.0989,
21.000
28.000, 28.188, 28.322
50.294
The 30 and 40 metre bands seem to be the most popular bands for QRSS operation although any band will give excellent results with the QRSS transmission being a good indicator when conditions are shifting and the band is about to open. It would be easy enough to modify the basic circuit in Fig. 2 to work on any band.
In conclusion
QRSS will give a very good indication of the propagation of radio signals for a given time of day over a given path. An improvement of signal strengths on one of the many Grabbers accessible via the internet will give an immediate visual indication in real time. Some interesting propagation phenomena become apparent after lengthy periods of time monitoring. The graphical representation makes it possible to detect minor changes in frequency and signal strength not normally possible by ear alone. As can be seen an early warning of changes in band conditions as they occur is possible using QRSS.
