Thursday, September 22, 2011


How to pass the time while WSPRing

Leading up to last weekend the sunspots were at an all time high along with the solar seemed that the radio god's were smiling on us again!! I turned on the K3 on the weekend and it was kinda a  down, it seemed that 20 meters may not had been as hot as I hoped it to be. I then turned to WSPR and thought I would give that a go on 20 meters as well. I wanted to put this solar hot spot to the instead of setting the K3 on the standard  3 watts output I dropped it down to 500mw's. I gave it a go and was surprised at the good
Dipole at 500mw's
results. Now I had always wondered when using that low power and my SWR after the K3's internal turner on 20 meters is about 2.3 what the

actual power out on the antenna is??? Well according to VK1OD.NET who offers a great RF transmission line loss calculator I could get a good idea. So I punched in all the necessary information I was told my setup is about 95.23% efficient. Well I punched the numbers into Google and it came up with 95.23% of (500 milliwatts) = 0.47615 watts. So I was pumping out 476mw's into my European contacts on WSPR.
 H900 on RX and dipole on TX 500mw's
Well I am some what of a gambling man so I dropped the power to 200mw's and that gave me an output of 95.23% of (200 milliwatts) = 0.19046 watts I was able to make some contacts with that power. I had also wanted to compare the ears of my attic dipole compared to my H 900 gain probe receiving antenna which is also mounted in the attic.
If you are a frequent user of WSPR then one knows it basiclly can run on it's own collecting what does the ham do during this down time..........start building his KAT100 antenna tuner of coarse!!

Dipole on RX dipole on TX 200mw's

H900 on RX dipole on TX 200mw's


  1. Hello Mike, good results with QRPp always fun to do. 73 Paul

  2. Well, the difference between your 500 mW and 200 mW runs should be about 4-5 dB. Did you notice that amount of difference in the WSPR list? Nice job! Perhaps I'll give it a try from here, though I don't think my SWR meter is so accurate.

  3. Good afternoon Paul, yes the bands were kinda dead for CW so I gave WSPR a go. I have to set the rig up for the digi modes as well and give them a go too.

  4. Good afternoon Casey, I did notice a differance between 500mw's and 200mw's. With 200mw's I was still getting into Europe but with only 2 showing they heard me at that power level. As for the SWR I have the LP-100A meter and it is fantastic! Look it up on the net and check it out. It comes as a kit.