Running WSPR (and QRSS) at 200mW

I’ve written a fair bit about WSPR in the past and posted reports of where my signal has been heard using just five watts output.  I’ve also written about QRSS including details of the transmitters I’ve built and shown reports of where I’ve been captured.

A few weeks ago I heard about a new QRSS kit from Hans Summers, the ‘Ultimate 2‘ kit which includes DDS frequency controlled output – A much better way of doing it than trying to tweak a trimmer for frequency and adjust a gimmick capacitor for bandwidth.  I ordered one of these kits along with a GPS module and the kit arrived late last week.

I assembled the kit on Friday afternoon last week and it went together really well.  There’s not much to do, just a handfull of capacitors, a couple of resistors, two transistors and one coil to wind.  The DDS module comes pre-assembled and that just left the low pass filter which is made of seven elements: four capacitors and three inductors, based on the W3NQN designs.

'Ultimate 2' QRSS/WSPR tranmitter, filter and DDS module by Hans Summers

‘Ultimate 2’ QRSS/WSPR tranmitter, filter and DDS module by Hans Summers

I ordered it with a complete set of filters, the first one I built was 20m so I put it on the air straight away using WSPR on that band.  I left it running for nearly 24 hours and by using the WSPRnet site, I was able to see where my signal had been received.

Map of stations where my 20m 200mW WSPR signal was received

Map of stations where my 20m 200mW WSPR signal was received

Over that (approximately) 24 hour period my signal had been received nearly 500 times by 62 different stations with the furthest away being WA7KGX at just over 7,900 km (4,900 miles) which I think is pretty good for just 200mW output.  Since then I’ve been spotted by K6PZB at a distance of 8,609 km (5,349 miles).

I’ve not built the transmitter into an enclosure yet, it’s just resting on top of my rotator control box.

'Ultimate 2' transmitter, transmitting on 20m

‘Ultimate 2’ transmitter, transmitting on 20m

And yes, that is a 5p coin glued to the DDS module acting as a heatsink!

I’m doing some 30m QRSS tests now.  QRSS isn’t so instantly gratifying as WSPR but it’s another good propagation testing mode so I’m keen to see how well it works.  I’m currently seeing myself on the LA5GOA grabber in Norway so I know it’s at least getting that far and that’s just on my random length doublet through an SGC smartuner.

G6NHU on the LA5GOA grabber

G6NHU on the LA5GOA grabber


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  1. I believe I have copied your qrss beacon on 20 meters (14000.760). Q5 with some fading at 2059Z on June 10, 2013… I have a screen grap of your signal..

    Antenna: G5RV @ 30 feet
    Transciever: TS2000
    Software: Argo 1.43

    Drop me a note at my email address and I can send you the screen grab..


    1. Thanks Bob, I’ve just dropped you an email.

      73 Keith.

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