136kHz ERP

A fairly easy way to increase my ERP on 137.5kHz WSPR is to up the supply voltage to the IRF510 PA. Using a 20-24V supply I was able to get another 3-4dB ERP judging by the reports from M0BMU and G3WCD this morning. This evening I'll give it a go with the higher supply to see if I can get any reports from further afield. I've also thickened up the bottom part of the loop which will reduce the resistive losses by about 15%.

DK7FC's VLF tests a great success

Stefan's latest VLF kite antenna transmissions at 8.97kHz and even lower frequencies were a great success yesterday with reception as far as Eire, Italy, Poland and the UK. The attached shot shows the signal on 2 frequencies as received by Renato IK1QFK in Italy.

M0BMU receiving DK7FC's 8.97kHz signal 10dB S/N

Jim reports that Stefan's DK7FC's 8.97kHz test signal is visible at 10dB S/N in Tring UK this morning. He is also visible on other grabbers in Europe. This is an excellent report and further encouragement for those of us taking our first (QRP) steps on the 33km band.

More 500kHz 2mW ERP DX reports this evening

This evening I switched back to 500kHz from 137kHz WSPR earlier in the day. Yet again good WSPR reports from GM4SLV and OH1LSQ (1733km) who received me as early as 1716z.

8.7 to 9.1kHz NoV received

This morning I received my NoV from OFCOM to operate legally around 9kHz (see copy on RHS - click to enlarge).

Details are:

• 1yr duration
  
• 8.7kHz - 9.1kHz 
• 100mW EIRP
• Modes not specified (long periodic modes preferred by Met Office)
• Met Office have to be informed of, and approve, operating periods and be sent logs
• Home QTH or /P locations only with prior Met Office approval

No firm plans yet when I'll start local tests on this band, but within couple of weeks with QRP WSPR and QRSS. I'll put a copy of the NoV on my website in the next few hours.

Struggling on 137.5kHz

Using the same TX output power (5W) and the same loop antenna I'm finding life is VERY much harder on 137.5kHz compared with 500kHz. Last night I was being copied right across Europe on 500kHz but tonight only 2 stations (best DX 69km) are able to copy me on 137.5kHz WSPR. The reason is simple: the radiation resistance is so much lower, so losses become more significant, and the ERP is very considerably lower. There is no doubt that to increase my "sphere of influence" on 137.5kHz I'll have to make some big improvements.

New DX record on 500kHz WSPR

This evening, quite unexpectedly, I got a string of reports on 500kHz from OH1LSQ in KP03sd at an astounding distance of 1733km. To me these are amazing reports pushing my best DX on the band with just a few milliwatts ERP to new levels.  What surprises me is how well a very simple wire loop works as a TX antenna: the wire is just 1mm diameter, with a loop area of around 70m square with part of the loop on the ground buried in wet grass. I now believe almost anything is possible!

Vertical loop success on 500kHz QRP

This evening I've been WSPRing on 500kHz running about 2mW ERP from my thin vertical wire loop with an area of around 70 sq metres. The bottom of the loop just runs along the ground and at the moment is buried in the long wet grass! Despite this, my signal is being decoded in G, ON, PA and GM with best DX tonight 896km to GM4SLV up in the Shetland Is.

Further 8.97kHz test this Saturday

DL7FC, Stefan, is planning another VLF kite antenna test this weekend Oct 23rd. I am assuming he will be on 8.97kHz again.

Additional SAQ VLF transmission

From SM6NM/Lars

There will be a transmission with the Alexanderson alternator on 17,2 kHz on United Nations Day Oct 24 2010 at 11:00 UTC. Start up and tuning from about 10:30 UTC. This time we do not require any QSL-reports and will not verify. We intend to continue with our annual transmission on Christmas Eve (morning), Dec 24, at 08:00 UTC with tuning up from 07:30 UTC. D.S.