31 Mar 2011

Transequatorial 70MHz QSO

SV2DCD and ZS6WAB have had the first ever 70MHz transequatorial (TEP) QSO on 70 MHz. It has also been announced that Namibia now has access to the band. Watch the video.

Earth mode VLF tests with E-field probe RX on car

As an experiment today I rigged up an E-field probe on the car to try to do something similar to LA3EQ's earth mode tests of the last few days. Instead of WSPR I used QRSS3 on 8.76kHz putting my usual 5W into the earth electrodes (one connection to the copper pipe ground and one at the bottom of the garden 20m away). The E-field probe consisted of my 1.5m long whip into an MPF102 source follower feeding a 2N3904 emitter follower with roughly the same arrangement as the PA0RDT E-field probe. The probe was attached at the top of a 2m long PVC pipe poking out of the rear window vertically. The actual E-field probe was powered by an internal 9V battery and was mounted about 1m above the car roof.

With the laptop PC running Spectran on the front passenger seat I was able to drive around and glance at the screen whilst moving. In the village there was a reasonable copy of the signal but outside of the village I only managed to get a couple of places 1km apart where the signal was strong enough to copy. One was at 2km and another at 2.1km. Compared with a loop on the ground at the same spots last year the signal was at least 10-20dB weaker. Although I am getting reasonable copy of the 11905Hz Alpha beacon the signal level is around 10dB down on the level on the 80m sq loop at home. So, maybe the E-field probe can be improved still.

In summary, with utilities assisted earth mode, for that is what the propagation is, the car mounted E-field probe is, as yet, nothing like as effective as a loop for RX.

I'd like to rig up some way of driving along with a horizontal loop attached to the rear of the car about 0.5m above the ground. This way I could drive around the local area and log where copy is possible. Presently I have to get out of the car with the loop to take a measurement when doing earth mode tests.

So, a useful test even though the results were not outstanding, or even good :-)


Seeing Jan LA3EQ's recent 4km earth mode tests with WSPR at VLF I must pass on something I'd forgotten about.

WSPR software is able to transmit a WSPR signal at least to 22kHz just by selecting the TX frequency to the chosen frequency. For example, if you want to send WSPR at 8.970kHz just select the band as "other", set the dial frequency to 0.000kHz and set TX frequency to 0.00897kHz. Listening to the tone it definitely is at the frequency stated.

What I haven't determined yet is how high the WSPR software will decode at. When I tried WSPR some time ago on 8.97kHz I used my up-converter and FT817 as the receiver. When I tried to decode directly at 8.97kHz today (setting the RX PC's dial frequency to 7.470kHz) it did not decode.

Bank bonuses - direct action Dutch style

Being really VERY annoyed with the size of totally unjustified bank bonuses in the UK, I was amused to read this article which proves that peaceful and non-violent "people power" can work. No need to spray paint on banks (pointless and unhelpful), just threaten, en mass to withdraw your money.


30 Mar 2011

A 100W PA for VLF use

BK Electronics in the UK make a range of MOSFET PA units with built-in toroidal power supplies. They have a 100W unit for £53, which is very reasonable for a built and tested unit. I believe these units work to 137kHz with a small modification and they would be ideal for 8.97kHz VLF use. There are versions up to 1kW, but these are quite expensive.

See http://www.bkelec.com/Modules/Amplifiers.htm

Easy mistakes

On Monday night I was looking for Uwe DJ8WX again on 8.97022kHz.  To my great surprise I copied nothing when G3ZJO and M0BMU were getting good copy. I'd copied Uwe several times before. After suspecting my PC sound card was faulty, I found out why I copied nothing tonight: on Sunday I'd retuned my loop ATU to copy M0BMU on 500kHz and I'd forgotten to retune it back to 8.97kHz. Although Spectrum Lab locked onto GBZ OK, the sensitivity was about 20dB down! We learn by our mistakes.

27 Mar 2011

G3XIZ a good signal on 8.976662kHz VLF today

Chris G3XIZ has just started TXing again and is a decent signal here in 424uHz bandwidth with the signal up to 20dB over the noise (see picture). Eddie G3ZJO was also getting a good signal. At 1530z Chris dropped the power 10dB but unfortunatley I was unable to copy at this QRP level, whereas G3ZJO was still able to.

Back from holiday

There have been no posts this last week as I have been away on holiday in Devon in SW England staying at my brother's cottage. For once the weather was excellent with wall-to-wall sunshine every day. I did not take any radio gear with me this time but plan to take the FT817 when I go next time to do some pedestrian portable cliff-top QRP DXing. Last May I worked some excellent European DX on 6m with just the FT817 handheld.

19 Mar 2011

Loop TX antennas at VLF

At first sight the idea of a 10m x 10m wire loop as a TX antenna at 8.97kHz VLF sounds a non-starter as a way of radiating any useful power. Having tossed the idea around with others though it appears that, although very inefficient, it would not be that much worse than a smallish Marconi vertical because these antennas need very large (and lossy) loading coils, height and good grounds to be effective. With 100W to such a small loop around 0.45uW could be radiated. Already G3XIZ has spanned 218km with just 2uW to his vertical, so for small gardens the VLF TX loop is worth a look.

18 Mar 2011

G3XIZ and DJ8WX on 8.97kHz

The Spectrum Lab plot showing reception here again of these two stations around 8.97kHz VLF. Both were using back garden antennas. DJ8WX is around 645km away. G3XIZ about 45km.

GPS cannot always be relied upon

As if to remind us of the vulnerability of modern technology yet again:
The MoD has informed OFCOM of the following GPS jamming exercise

Dates: 19 – 26 May 2011.
Times: limited periods between 0700z 19 May to 100z 2 May 2011. 

Location:  The ground based radar jamming events will take place in the SW approaches against the remote radar head at Portreath 21-22 May, undertaken by F-18 Growler aircraft. Additionally there will be radar jamming against deployed targets in South West Wales throughout the period 19-26 May. Communications and airborne radar jamming will take place throughout the same period on the East Coast with aircraft operating within the North Sea Military Danger Areas. Communications and maritime unit radar jamming will take place in the SW approaches and Bristol Channel. Falcon aircraft will operate from Sea Level to FL240 unless jamming AEW aircraft where they may operate above FL245.

Note: Safety of life operations will take precedence over exercise activities at all times.

Emergency radio kit

The terrible Japanese earthquake, tsunami and nuclear crisis has reminded us all that modern 1st world technology cannot always be relied upon. The UK Foreign Office and the BBC have webpages suggesting essential items as an emergency "grab bag" to have ready in such circumstances. One of the attractions of simple QRP gear is its ability to work when nothing else may, for example using a small battery or solar cells with a compact CW rig that can be taken anywhere with a throw-out HF antenna. In the event of a sudden and unexpected disaster, would you and I be able to communicate still?

17 Mar 2011

8.97kHz very sensitive spectrogram online

Paul Nicholson in Todmorden, Yorkshire UK has put on line his steerable and highly sensitive spectrogram for the VLF Dreamer's Band around 8.97kHz. Paul's system is super sensitive and detects just about anything going. His new spectrogram can be "steered" to a specific direction and the display clicked to show exact frequency and S/N levels. There is also a roll back function so that records from a few hours to days back can also be checked. Marvellous! See http://abelian.org/vlf/fbins.shtml

15 Mar 2011

Great care needed when IDing VLF stations

A word of caution to those of us looking for very weak signals around 8-9kHz. DJ8WX was copied here overnight on 8.970022kHz without any doubt and my grabber was clearly able to see his close-down around 0700 today. The frequency and the trace timing corresponded perfectly. Likewise with G3XIZ and DK7FC/P some weeks ago.

This evening I was looking very carefully again at the Spectrum Lab screen from the last 24 hours in 424uHz BW and readjusting audio gain ranges, screen colour saturation and contrast. Out of the noise appeared another very very faint line, not at 8.970022 but at 8.96998kHz. I've attached the screen shot here (I have overlaid it with the time for clarity).

My immediate reaction was this must be Ossi OE5ODL as this is the frequency he uses. Then I checked his grabber and saw he was not operational overnight last night! So, what looked like a trace on his frequency cannot be him. It must instead be some artefact of SL or something else. We have to be very careful when seeing traces at very specific VLF frequencies: it may be an indication of a given VLF amateur station, but without some modulation or turning on/off of the carrier a doubt remains.

Sadly I don't think I did see Ossi today after all, but I shall keep looking.

14 Mar 2011

New Sub-9kHz Amateur Radio website

For some time I've wanted to tidy up the pages on my website that dealt with the various aspects of VLF amateur radio below 9kHz. So, today I've launched a new site entitled Sub 9kHz Amateur Radio bringing together my information more accessibly. The original pages just grew and grew as activity at VLF just took off. It is almost 1 year to the day since DK7FC made his first historic DX on 8.97kHz. Since then we've come a VERY long way!

The new site has a table showing the VLF DX records. This is not fully populated or correct yet, so I need everyone's help to get this up to date in the next couple of days please. If you are aware of errors or omissions please let me know right away.

Another addition - to be much expanded - is a page on TX stations and their equipment. Please let me have photos, schematics of antennas, transmitters, loading coils etc.  Another page deals with the kit needed to receive on the Dreamer's Band. It is easy stuff that can be built by anyone. Also a page linking the various software packages available freely. Yet another page lists the VLF grabbers (incomplete still - tell me of others!) which are such a vital resource. 

Also included on the page is more data on earth mode (through the ground) communication which is a very accessible way of starting out on VLF as much of the kit is re-usable for experiments with radiated VLF tests (same loops, probes and pre-amps can be used).

Please let me have constructive feedback so I can make this as good as possible. I hope you enjoy the site.

13 Mar 2011

The end fed halfwave antenna (EFHW)

Steve G0KYA has a nice pdf document he's created describing how to make simple end fed half wave antennas (EFHQ). These band specific antennas can be very effective and simple when mounted either vertically or horizontally. They can be made with PVC covered wire, fishing poles or aluminium rod. See http://www.infotechcomms.net/downloads/Endfed_halfwave_dipoles.pdf.  Many years ago we experimented with these on VHF handhelds and achieved results some 6dB better than with a standard 1/4 wave whip, but on 2m they were on the long side! On HF they are capable of low angle radiation good for DX.

4m QRP success - 229km today in the contest

Using my small 1W QRP 4m transverter recently built into my loft dipole I've just managed a QSO with G4RFR 229km away in Dorset (IO90AS) using CW in the RSGB Cumulative contest. He was on SSB and it was hard work, but in the end a full exchange was made.  Also heard G3EDD, G4ASR, G3BCU, G3TCT, G4DEZ, G1EHF on the band on SSB and G4ZTR on CW.

DJ8WX copied again on VLF (645km)

Uwe DJ8WX is currently transmitting a long dash on 8.90022kHz and his signal was copied well on my VLF grabber overnight in a 424uHz bandwidth. Also visible is a mystery signal around 8.9701kHz that most people think is some sort of local noise source but it is very repeatable every night.

12 Mar 2011

Monitoring 8.976607kHz for G3XIZ

Just back from a few days with our grandson and family and the PC is on looking for the latest VLF test from G3XIZ. Whilst I've been away I hear that OK2BVG has been received in the UK too on VLF. Activity on the Dreamer's Band (8-9khz VLF) is going from strength to strength with new stations getting active on RX and TX almost daily now in Europe.

10 Mar 2011

10m WSPR - reports from Australia today

WSPR reports 10.3.11 morning

This morning my 5W WSPR signal on 28MHz reached Australia with reports from VK5ZK and VK6DZ. Best DX is 16275km, a new WSPR record for me on the band. In the last 3 months I've had WSPR reports from 6 continents. Not bad with 5W to a small wire halo antenna at this stage of the sunspot cycle. At 1100z I'd been received by no less than 4 different Australian stations plus Israel, the Faroes and UK.

DJ8WX on 8.970022kHz again

Just weak a very weak trace overnight (you have to look hard!) from DJ8WX on VLF. Compared with his signals a few days ago he is at least 10dB weaker. Not sure why as nothing has been changed here. G3ZJO also copied Uwe weaker than before, although Eddie was getting him slightly better than me using his E-field probe antenna. By the way, this small trace (in blue/white) covers a period of 8 hours and is looking for the signal in an incredibly narrow 424uHz (yes you read it correctly - microhertz) bandwidth.

9 Mar 2011

10m WSPR DX today

28MHz WSPR reports today

Whilst doing other work I left the 10m WSPR beacon system running today. Some decent DX about with the best being reports from FR1GZ and the two Israeli stations.

8 Mar 2011

Dazed goldfinch

One dazed little goldfinch with a headache!
This little goldfinch crashed into our bedroom window yesterday morning. When I looked, he was just sitting on the roof very dazed. I opened the window, took this photo from about 10cm, stroked him ....and off he flew!

Jazz at Ronnie Scotts in London

Tim Lapthorn at Ronnie Scotts
Our son Tim shown here on the piano at one of his many recent appearances at the world famous Ronnie Scotts jazz club in central London. His new album "Intentions" is due out later this year and will feature many of his new original compositions. See www.timlapthorn.com .

Latest NASA sunspot predictions

From the http://solarscience.msfc.nasa.gov/SunspotCycle.shtml website dated March 1st 2011:
"Current prediction for the next sunspot cycle maximum gives a smoothed sunspot number maximum of about 58 in July of 2013. We are currently over two years into Cycle 24. The predicted size would make this the smallest sunspot cycle in nearly 200 years."
Gloomy reading? Very recent solar levels in the last week or so may be just a blip, but something tells me we could all be in for a very big, and pleasant, surprise should activity continue to build as rapidly as it has recently. The sun is still full of surprises and no-one predicted the 2 year quiet sun we just had at the end of cycle 23.

I still find http://www.solen.info/solar/ the best page for up to date information on current solar activity.

6 Mar 2011

Doppler shift on 10m WSPR Transequatorial

This afternoon, before working some QRP DX on 10m and 12m SSB I had my WSPR system running and spotted FR1GZ (Reunion Is) several times at good levels. What was interesting was the Doppler shift on his signal which was up to -3Hz at times. I guess the propagation is trans-equatorial spread-F and what I'm observing are moving F-layers on the path between us.

Welcome back 10m "big time"

Today 10m sounded like the good old days with good strong contest signals from the USA and Canada as well as South America and Africa earlier in the day. I managed to work several stations in Texas, Alabama, Tennessee and Louisiana when running QRP SSB to the Homebase10 wire halo. This is the first time in around 5 years that I've heard the band like this. Welcome back good old 10m!

A busy VLF amateur band (8-9kHz)

DK7FC's 8.97kHz grabber showing 4 stations active!
This screen shot from DK7FC's grabber shows just how busy this band is now becoming and how much progress has been made in the last 12 months. Visible in the grab taken March 6th 2001 are DJ8WX, OE3GHB, DK7FC (local testing) and DF6NM. Only a year ago people dismissed experiments at sub-9kHz as dreaming whereas today stations are regularly getting reports from anything from a few km to nearly 3000km for the better equipped stations.

This is REAL ham radio at the frontiers folks - put your cheque books away, forget those black boxes and join the fun on the Dreamer's Band.

5 Mar 2011

28MHz simple WSPR transceiver idea

Whilst playing with VXOs for my 10m DSB transceiver I realised that a cheap 14.060MHz crystal (available widely for about £1-2 each) would make a nice LO source for a 28MHz direct conversion WSPR transceiver. Doubled, the output is easily pulled to 28.1246MHz, the WSPR frequency. The PA does not have to be linear, so all that is needed apart from an oscillator/doubler is a single balanced mixer followed by a small PA. With the DSB approach, half the power is wasted and there would be an audio image 3kHz away on RX. However, the audio stages could be filtered to allow just 1.4-1.6kHz through. The whole transceiver could be extremely simple and stand-alone. I must build one.

ARRL SSB DX contest

Although there are US stations coming through on 15m, I've not yet heard any on 10m. Signals from LU1UM on 10m but nothing yet from North America. Sunspot count is high but conditions on 10m do not sound that good. Just worked N2PP on 15m SSB when using 10W to my 28MHz halo!

VLF Dreamer's Band video

For those interested, I've made a short video showing my current VLF receiving set-up for 8.7-9.1kHz (antenna, matching, preamp, PC) used in the recent VLF reception tests in which G3XIZ has been copied twice now (45km), DJ8WX all of yesterday (645km) and DK7FC/P twice (629km). I am not claiming it to be fully optimised, but it certainly works.

What I like is that the wire antenna and the preamp cost a few pounds, the software is free (thanks Wolf) and the results mind blowing. In the near future I will try replacing the loop and preamp with a small E-field probe.

This is the link http://www.youtube.com/watch?v=UxEAhqPFBFE

Also, G3XIZ was copied again on 9.0909kHz VLF at 45km. He was also copied by a few other UK stations including G3ZJO and M0BMU.

3 Mar 2011

DJ8WX received on 8.970022kHz

DJ8WX on 8.970022kHz VLF (645km)
Overnight tonight I received a new station on VLF:  Uwe DJ8WX who is 645km east of me. Uwe was a solid signal here in JO02dg in the early hours on 8.970022kHz. His signal level dropped off during the night somewhat but he was still visible at 0500z. Spectrum Lab settings were as for the G3XIZ reception the previous night with the FFT bandwidth set to 423uHz. This is the 4th ham station now copied at VLF in 4 unique locator squares and 2 countries.

G3XIZ copied on VLF (at last)

G3XIZ received on VLF
Overnight, Chris G3XIZ was transmitting a test carrier on 9.0909kHz using 80W into his normal inverted-L antenna used on 136 and 500kHz matched with a large VLF loading coil. Using Spectrum Lab software and 423uHz bandwidth FFT settings I managed to get quite good copy of his signal using my 80 sq metre loop and small FET preamp. Between 0300-0600 his signal was around 10dB S/N in this bandwidth. Distance between us is around 45km. Later I got this email from Chris:
"You've re-awakened my enthusiasm which I must confess was fading. You are absolutely correct -  I checked the transmitter about 02.30 and found that the aerial current had dropped off, maybe due to a change in loading coil inductance with temperature. I increased the drive and brought it back to the initial level of 0.18 A. You and I seem to be at the extreme range with my current set up and if the new loading coil is more efficient we must try the experiment again. I am pleased that the OCXO seems to stable enough for our purposes. Once I've cured my off air standard of losing 'lock' I'll use that as the frequency source. My TX input power was 120 watts giving an output RF of about 80 watts. This should automatically be increased with the better loading coil."
UPDATE: Paul Nicholson in Todmorden Yorks has confirmed he received Chris at a distance of 218km, a new record for a UK VLF ham station.

1 Mar 2011

International Short Wave League (ISWL)

It's the 65th anniversary of the ISWL this year. The ISWL is an international club for radio amateurs, shortwave listeners and broadcast band listeners from all over the world. They run a very wide range of contests covering all aspects of the hobby for both listeners and transmitting stations. Every month they produce a magazine filled with articles, reports and news items of interest. Subscription is just £20 a year and good value for a magazine running to around 60 pages every issue every month.  For more details about joining this International Short Wave League see www.iswl.org.uk/.  Also, look out for the club's special callsign GB65ISWL during the year ahead.