QRP Labs
Si570 based 30m QRSS beacon PDF Print E-mail
Written by Hans Summers   
Tuesday, 13 January 2009 19:09

This project came into being when Jan G0BBL kindly gave me one of his SRR-Kits USB Si570 synthesiser modules. I added a junkbox IRF740 MOSFET PA, Low Pass filter and ATtiny13 AVR keyer and put it on air on 30m QRSS for some reports! I used a 30m dipole: 7.1m long on each arm and with a balun at the centre consisting of 6 bifilar turns on a T37-43 toroid, driven by a length of RG58 coax direct from the PA (no ATU). Read here for how to construct a similar balun. The dipole is 2 stories up the building but is close to the building, well shielded by metalwork for several metres of one end, and also well shielded by surrounding high buildings... so it was a real pleasure to see my signal getting out so well.

Transmission details:

QRP 520mW
QRG 10,140,020
QRV 01-Jan-09 2000 UT until 05-Jan-09 2224 UT
QTH London, UK
Ant 30m dipole
Msg 5Hz FSK CW 6s dots, repeated "UPL"

After running the beacon for 5 days I'd received a good number of reports from Europe and North American and switched off the beacon. I concluded that the Si570 module is extremely stable. The programmed frequency was about 30Hz higher than the actual frequency. The thermal stability was excellent, no measurable drift at all was evident during the 5 days. One disadvantage of using this Si570 module as an FSK source for a QRSS beacon in this mode is that it requires that the USB host (an old 333MHz Pentium II PC in this case) must be switched on 24 x 7 to provide the FSK.


Construction details are presented here. All other components than the Si570 module i.e. PA, Low Pass filter etc were from the junk box.



During 5 days of operation 24 x 7 a good number of reports were received from stations in Europe and North America. On this page I've included a representative sample of some of the best reports.

30m QRSS Receiver:

Don't miss this related project: a simple 2-chip 30m QRSS crystal controlled direct conversion receiver powered with +5V from a computer's USB port!


List of receiving stations

Currently reports have been received from 9 stations as follows:



Location1st ReportNotes
1.I2NDTClaudioJN45TQ Bergamo, Italy03-Aug-08First operation on bad longwire. Subsequent report in 2009
2.W1BWBruceFN42HL Concord MA, USA02-Jan-09First report in 2009 on new 30m dipole
3.W8LIWLarry  Northwood OH, USA02-Jan-09Faint but identifiable with some imagination. A better one.
4.ON5SLPierreJO10TT Belgium03-Jan-09 
5.VE1VDMVernFN85KI Nova Scotia, Canada03-Jan-09Stronger report!
6.PA1SDBPeterJO33KH Appingedam, The Netherlands04-Jan-09 
7.IZ1KXQPaolo  Sarzana, Italy04-Jan-09 
8.G6AVKColinJO01HO Rayleigh, Essex, UK04-Jan-09 
9.IK2JETAlberto  Lonato, Italy05-Jan-09 


Knights webpages:

I2NDT Claudio
W1WB Bruce
W8LIW Larry
VK6DI David
WB3ANQ Larry
DL6JAN Christian
IW0HK Andrea
I0SKK Alex
OE5EEP Heinz
AK0B Stan
G6AVK Colin
G7IZU Andy
I2PHD Alberto
G4OEP Andy

QRSS Information and QRSS Knights mailing list:

QRSS Knights mailing list
QRSS Knights website

QRSS Software:

ARGO: the most popular QRSS viewer program

Propagation pages:

Digisonde - current propagation
Propagation theory pages by G4NSJ
Earth Viewer

Construction aids:

Mini ring core calculator
GQRP club guide to harmonic filters


Peter DL6NL has a QRSS frequency HC49 crystals for sale. He has the following frequencies: 7.000, 7.020, 10.137 and 10.140. Price is 5 Euros for three crystals, including shipping. Email him at his AOL address:

Beacon keyers:
Last Updated on Saturday, 20 June 2009 06:41
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