Optical DXing at around 460THz

Until I read the webpage below I didn't know that the record for optical morse DX goes back to 1896 and was an astounding distance of 183 miles using a Heliograph between Colorado and Utah in the USA. This link about the heliograph makes fascinating reading. The heliograph is essentially a keyed mirror that reflects sunlight and uses it to send morse code over long distances.  Modern versions of heliograph mirrors are available on eBay for emergency communications. See for example eBay item 250681260168. A good article about heliographs is on Wikipedia, see http://en.wikipedia.org/wiki/Heliograph.

Modern amateur optical DXing uses either lasers or high intensity LEDs. There is a piece about this on p51-52 of the Feb 2011 RSGB RadCom in Sam Jewell's "GHz Bands" column with further links including http://www.lasercomms.org.uk/index.htm which looks like a useful resource.  There was also a funny article in the RSGB Bulletin of April 1962 called "Getting Going on Bottom Band".  

Dreamer's Band activity around 8.97kHz

In the last few days OE3GHB and OE5ODL have been testing close to 8.97kHz with their signals (from home QTHs) being received at considerable distances across Western Europe. DK7FC was planning his 10th kite VLF test this weekend but has had to postpone this until Jan 29/30 because of the weather. My grabber is currently looking around 8.97kHz and seeing a strong signal, although I suspect this is a locally generated interferer. See http://dl.dropbox.com/u/15047843/xbm_grab.jpg for the grabber as it updates. This is not on all the time, just when I am testing or listening.

Corporate Greed

I don't usually get political on my blog, but something has incensed me this week. Goldman Sachs, the huge multi-national finance company, has declared huge bonuses for its staff. In the press yesterday it was reported that their staff now have an average salary+bonus package of $430000 a year!  At the same time I've read that they've slashed their corporate charity giving by a large amount. If these figures are correct, then I believe them to be obscene and a prime example of the corporate greed of some big financial institutions. I am not sure how to respond, but want to email their CEO, but haven't managed to find his email address on the swish corporate website!  In the end, such greed cannot be acceptable. This is the sort of behaviour that festered revolutions a century ago: the seeds are there for it to happen again within 10 years when the ordinary man says, "no more".

5mW on 80m - best DX 1310km

80m WSPR with 5mW output

This evening I ran 5mW output on 80m WSPR to see what sort of distance I could achieve. It was quite an eye-opener with lots of reports and some good DX, the best being LA2XPA at 1310km. The report from LA3JJ suggests that almost 1000km would have been possible with 500uW. And it is not as if the antenna here is anything: just 5m of coax to the 10m halo with inner and outer joined together as a vertical and tuned through a tiny T1 auto-ATU!

FT817 lowest power setting at 500mW

Do you know, I've only just realised something about my FT817 having owned it for almost 10 years: as someone pointed out to me, the lowest setting on the FT817 is always 500mW whether on an external supply or internal batteries. For some reason I had believed "1 dash" on the display was 500mW on batteries and 1W on a mains PSU. I just checked and it really is 500mW out.

So, my recent WSPR DX spots with 10mW and 1mW were actually at 5mW and 500uW!

Reverse Beacon Network

Thanks to Mike Rainey AA1TJ for putting me on to this. The Reverse Beacon Network is a revolutionary new idea. Instead of beacons actively transmitting signals, the RBN is a network of stations listening to the bands and reporting what stations they hear, when and how well. It works by using skimmers to check activity and then uploading spots to an internet database much like WSPRnet for WSPR spots. Using it you can see if your signals are making it to a given spotting location.

1mW DXing on 40m

Today I reduced the power from my 40m WSPR beacon TX from 10mW down to just 1mW. The FT817 is run at minimum power setting (1W) then via a 20dB attenuator within a few cm of the antenna connector and then into a 10dB stepped attenuator. My antenna is the 5m coax feeder (inner and outer strapped together) up to my 10m halo and tuned via the Elecraft T1 auto-ATU. The first report received at 1436 today was from DC4FS at 523km (-28dB S/N).

VLF earth-mode tests legal without NoV

Today I received a letter from OFCOM, which clarifies the legality of operating so called "earth mode" (conduction/induction via the ground) experiments at frequencies below 9kHz in the UK. In it, the official from OFCOM stated, "We would not normally issue NoVs for communications using non-wireless telegraphy apparatus/stations i.e.  where you rely only on conducted emissions and where there are no intentional radiated emissions.".

Wanting to check earth mode propagation behaviour at a series of frequencies below 9kHz to see how results compared (earlier tests at 0.838kHz seemed around 10dB better than at 8.76kHz), I asked OFCOM if I needed an NoV extension to be legal. One could reasonably also argue that such through the ground conduction tests at frequencies above 9kHz would also be legal as long as they don't cause any "Undue Interference to any wireless telegraphy" and one was not intending to radiate.

This sounds a wholly pragmatic answer from a government body.

PA1B's QRPp website

Whilst looking at the links on PC4T's blog I noticed Bert PA1B's excellent website all about QRPp operating with lots of tips on how to produce mW power levels and have real fun on the HF bands.

This has encouraged me to have a go, so I am currently WSPR beaconing on various HF bands using 10mW out from the FT817 via a 20dB attenuator right next to the rig.These were the results from 40m late this afternoon and into the early evening. Encouraging!

Best DX 983km with 10mW in just a few hours!

136kHz RX activity

In the last few weeks I've received 136kHz signals from several different countries and stations:

DK7FC/P     CW/QRSS
DF6NM     QRSS
G8IMR      WSPR
M0BMU    WSPR
PA0A    WSPR
SM6BHZ     WSPR

Certainly my receiving system is now up with the best since adding the tuned preamp. My main drawback is the TX/RX loop's directionality which reduces signal levels in a N-S direction. We just need a lot more stations active on the band, especially on WSPR.