QRP Labs
Tropical QRSS PDF Print E-mail
Written by Hans Summers   
Saturday, 18 July 2009 01:03
18-Jul-09 to 29-Jul-09
Grenada, Caribbean
Dipole, aimed at Europe
"UPL" in FSKCW with 4Hz shift

I designed, built and debugged this 30m QRSS beacon in 2 hours, from 3 o'clock a.m. until 5 o'clock a.m. in the early hours before we left for the airport. It was a real last minute job! As such the design surely isn't perfect, and the construction a bit messy. I finished it just in time! It is built in a tiny Ozon mint tin and powered by my mobile phone charger: saves having to pack a separate PSU! The local copy of the signal (using my 30m QRSS receiver) is shown above right.

The design:

  • 2N3904 Colpitts transistor oscillator
  • 2N3904 buffer
  • 2N7000 FET "PA"
  • 7-element low-pass filter
  • Keying via ATtiny13

The ATtiny13 keyer wasn't built for this project, it was built for an earlier project, see my Si570 beacon project. The circuit diagram:

Here are some photos of the construction:

Aerial and installation

Below are some photos of the antenna installation. The villa in Grenada was on the hill overlooking Grenada's only golf course (9 holes). The antenna was a wire dipole with each leg measured at 7.1m long. At the centre was a balun made of 6 bifilar turns on a T37-43 toroidal core, fed by 5m of 50-ohm coax. The coax was fed directly by the output of the 7-element low pass filter in the transmitter. No ATU and no attempt to tune the dipole by trimming etc.

I used string to suspend the dipole so that the wire would be less likely to get snapped in the windy conditions on the hill. One end of the string was attached to the car port roof and the other to a bush by the road side. The roof of the villa is tin so would have had some shielding effect. The antenna was only 1m from the roof of the villa and below street level for most of its length, though perhaps 4m above the swimming pool for part of its length. I hope the photos give some better idea that will aid this description.

The orientation of the aerial was such that the perpendicular (and direction of maximum radiation) should point approximately North-East - as judged by where the sun rose and set - and therefore approximately in a European kind of a direction. Given the close proximity of the tin roof and the number of approximations involved I'd be very surprised if the radiation pattern was anything close to dipole theory! One of these photos shows the view from the antenna to the North East so that you can see that even if there was a hill behind, and a tin roof 1m below, at least the view towards Europe was somewhat unobstructed!

In a couple of those photos you can see how the Ozon mint tin transmitter was taped under the eaves of the house. The red wires go into the house and were taped to my Nokia phone charger, providing 5V with more than enough mA to power this small QRSS signal.


A sample report from each station who copied the beacon is shown below. Immediately on switch on, I looked at the online grabbers and saw the signal clearly at G8NXD, W1BW then ON5EX. The local time in Grenada was about 20:19 (i.e. about an hour after dusk, by the time the antenna farming was complete). On the grabbers of W1BW you can see the moment of switch on at 00:19 GMT!

Mike G8NXD

The first "report" was when I looked at the grabber of Mike G8NXD and saw the signal clearly there in IO70JE! Right after switch on! Note the signal was originally down on around 10,140,005. Later I tweaked the trimmer capacitor to bring it up to around 060-070 so that with the daytime heat, drift would not take it out of the magic 100Hz sub-band where all QRSS'ers listen.

Bruce W1BW

Next I looked on the grabber of Bruce W1BW and there was the signal again, no problems to the US in FN42HL either! Still down around 005 - 010 at this time. Note the switch-on visible at 0019Z!

Johan ON5EX

The signal was also visible in Belgium JO10UX on Johan's grabber. Note the switch-on visible at 0019Z!

Michael DL4MGM

Michael sent a nice shot from Germany, his receiver on LSB with 10.148MHz crystal. Michael writes: "here is the grab when I spotted the Grenada beacon just touching M1CNK at about 22:00 UTC last Saturday.
Hans and M1CNK are in the center with a strong IQ4FJ/p to the left and I0/N2CQR on the right."
Martijn PA3GFE

Martiyn writes from The Netherlands: "Nice to see Hans in Grenada visible yesterday evening! At 22.30 UTC the signal here in the Netherlands was the strongest (on screenshot just above M1CNK)."
Larry WB3ANQ

Larry's report on 20-Jul-09 at 22:52 UT from FM19rc (Pasadena, Maryland). He writes: "Here is one on the captures of Hans  and the triangles [G6AVK]. Both signals were visible for a few hours but the first few were the strongest just prior to sunset here. Using Elecraft K3 and Force12 40XK vertical dipole.
Joachim PA1GSJ

First report from Holland on 20-Jul-09 at 22:09, from Joachim who writes about his equipment: "direct conversion with a J310 front-end, a 5.0688MHz canned osci and a ra3aae-mixer. ANT: indoor rockloop"


Fine strong signals received by Jan G0BBL at 2310Z on 20-Jul-09. Jan also reported reception on the following two nights and said that reception was generally good at his QTH between about 2300Z fading out at around 0200Z.

Alan M0PUB

Good copy also from Alan M0PUB, this example is on 21-Jul-09 at 23:16 (2216Z). Alan reported that the signal faded on that occasion at around 23:40 local time (2240Z) but on previous evenings was visible several hours later.

Steve G0XAR

Nice report too from Steve G0XAR in Norwich at 23:32 local (2232Z) on 23-Jul-09. FB OM!

Pierre ON5SL

Pierre sent a nice report from JO10tt (Etikhove, Belgium) on 27-Jul-09 at 01:56 and writes: "Hans in company with : IQ4FJ/p , KC7VHS , WA5DJJ and I/N2CQR ( incognito)"
Colin G6AVK

Colin had a grabber running and this is a very nice strong shot from his grabber. Ignore the "grabber offline" message! Actually Colin sent in a report way back on 19'th July, but this one from 27-Jul-09 23:06 is stronger and more interesting so I'm showing it here!

Finally, while the beacon was busy whispering to the world, we were busy enjoying Grenada, and here's some photos of what we enjoyed!


Last Updated on Saturday, 21 November 2009 23:05
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