What is my ERP currently on 137kHz WSPR?

Based on some measurements and calculations using the improved ATU (see photo) today, this is my calculation:

Measured antenna current in the TX loop = 2.13A
Area enclosed by the loop = 80 sq m
P = (I^2 x A^2)/(205 x 10^6) at 137kHz   (see p101 of "LF Today" book available from RSGB)
where P = ERP,  I = current in amps and A = loop area in sq m

P = (2.13 x 2.13 x 80 x 80)/(205 x 10^6) = 141uW

This is not a lot (but more than ever before) and this is before I start on the "ERP improvement" programme.

137/500kHz ERP improvements

Today I made a start on improving my ERP on 137kHz and 500kHz.

Firstly, I've bought a pile of Wima 1000V polypropylene capacitors from Farnell. With these I have now made a new ATU to match my TX loop (breadboard only ATU so far) which will allow me to run some 6-10dB more power into the loop without the ATU components overheating and failing. My old switched capacitor array was an old school capacitance decade box and this was marginal with tuning changing as caps heated up!

Secondly, I am going to change the MOSFET PA design to increase the 137kHz power from around 7W RF to about 30W. This should be worth around 6-8dB. I plan to do something similar on 500kHz too.

Finally, I've got some more wire to allow me to double the thickness of my TX loop. This will be done later and will be worth 2-3dB as long as I alter the 3C90 ATU (step down) matching transformer.

In all, these changes will give me up to 10-13dB more ERP and, with some luck will allow me to get more reports on QRSS and WSPR. It will take some weeks to implement these, but by late October my range should improve on both bands.

VLF NoVs to be extended

OFCOM has confirmed that the UK NoVs to operate in the 8.7-9.1kHz VLF band will be extended later this year if holders request this.  Discussions with the Met Office have confirmed no problems have been observed with operation in this band. This is good news. Currently there are, I believe, 4 VLF NoV holders in the UK: G3XIZ, G3XBM, G4WGT and G7NKS.

WSPR database issues

Some people in the UK, including me, have been unable to find wsprnet.org today. After working perfectly overnight the site just disappeared and via Virgin Media and just some other ISPs it isn't available currently. For others it works OK. This isn't the same as the recent overload issues: something has changed at their end or in the way the site connects to the internet. Hopefully all will be resolved soon or I'll have to resort to CW more often!

A useful site to check connections is http://www.downforeveryoneorjustme.com/# which allows you to check if a site has really disappeared or not. According to this, wsprnet.org is still there, so I assume it is a routing issue.

Shortly before the link was lost I was getting VK8AW well on 10m WSPR. Guess I'll have to wait now to see if my 5W WSPR signals made it to Australia this morning.....

UPDATE: 1415BST - it's back.

US politicians and science - are their politician brain dead?

As the USA starts its next election campaign I'm seriously worried that the country is likely to end up being run by a brain dead, ignorant and downright dangerous politician from the fundamentalist, anti-global warming, anti-science, isolationist brigade. See this article from the New York Times kindly sent to me by Michael AA1TJ.  Although this is about republicans, there are as many democrats with equally stupid views. It seems you have to be stupid in all things (apart from making money) to make the grade over there.  Seriously, we are talking about the nation that is supposed to show the world a moral lead, to champion policies to safeguard the planet.

American citizens, please use your head when selecting you future politicians as it matters very much.

10 unique reports on 500kHz

Stations copying me on 500kHz WSPR

Last evening's WSPR outing on 500kHz was very successful considering this is August. 10 different stations managed to receive and decode my 1mW ERP signal with best DX report from EI0CF at 602km. Best seen here was GM4SLV in Shetland at 896km. This just using a thin wire vertical loop (80 sq m area) around the garden with the lowest side running along the fence in the foliage!

Back on 500kHz WSPR

This afternoon John GM4SLV informed me he was restarting tests on 500kHz WSPR from way up in the Shetland Islands with about 150mW ERP.  So, I've fired up my own 500kHz WSPR system in the hope of copying him later this evening. So far I have had spots of my own 1mW ERP signal from several stations with best DX so far being PA3ABK at 306km, but nothing seen (yet) from John. I'm hoping a few more stations will appear too.

http://goo.gl/

Just discovered Google also do a "shorten your URL" feature too. Go to http://goo.gl/ to try it out. I knew about tinyurl but only just noticed the Google equivalent. As with other shortened URLs, some security systems may recommend avoiding such links.

Bitsbox - an excellent UK component supplier

Just a couple of days ago I placed an order with Bitsbox, a UK component supplier for a variety of components needed in my upcoming VLF/LF experiments. Today, by first class post, the order arrived. Bitsbox charge a fixed £1.50 first class post charge which is very reasonable. The service and value for money are truly excellent. Their website is www.bitsbox.co.uk  and they stock a wide range of useful parts.  If you've not used them before, and I had not, I can highly recommend them.

Heathkit kits again?

The Southgate amateur news page carries a story that Heathkit may be about to start the production of kits again after a break of many years. This would be excellent news. Heathkit used to produce world class kits that were in a class of their own with first class instructions. Let us hope they decide to restart amateur radio kits as well in due course. In the amateur radio field Elecraft are the nearest.