G3XIZ sub 10kHz

This photo was taken some years ago and shows the signal from G3XIZ on VLF at 45km. Notice the timescales - hours!! 

472kHz spots from G3XIZ

During the day time I get -15/-16dB S/N spots on 472kHz WSPR from Chris Osborn G3XIZ who is 46km away. G3XIZ is about 20dB stronger here, which is about right for the ERP difference (500mW to 5mW).  At night, my reports are poorer, probably because the local noise at G3XIZ is higher? This all seems about right.

Chris has seen my WSPR on 137kHz from the old QTH, but with the 15m  baseline earth-electrode antenna at this newer QTH 137kHz would be marginal or not good enough except perhaps when the band is exceptionally quiet. A longer baseline earth-electrode antenna may allow the path to Chris to be useable on 137kHz again. It may be some time before I can find out.

UPDATE April 26th 0900z:   G3XIZ says my WSPR sigmal is strong enough for a CW QSO. We must have a go sometime.

The Low Power SPRATbook.

http://www.rsgbshop.org/acatalog/

Today, my new paper logbook (yes I still use a paper logbook!) and a new book arrived from the RSGB. The book was the Low Power SPRATbook, recently published by the RSGB and edited by Steve Telenius-Lowe 9M6DXX. As I want to de-clutter and possibly clear the book shelves of my old paper SPRAT copies (I still have them on DVD), this book was ideal as it contains a very good selection of the best of SPRAT articles from 1974-2012. If you have not read SPRAT and seen the excellent articles each quarter, then I recommend this book. I challenge you to buy it and not be inspired to build something.

Perhaps I should also mention that my 14 component 80m CW transceiver is one of the articles. But don't let that put you off! The circuit works well and G3XIZ worked GM with his version (despite running only about 18mW) and was copied on Switzerland.

First CW QSO on 472kHz

Although my local noise level is a little lower on 472kHz than on 500kHz it is still not low, so working stations with the current TX antenna (using it on RX and TX) is not the best of set-ups. Nonetheless, this evening I had my first 2-way QSO (on any band) of 2013 and this was on 472.5kHz CW with G3XIZ in Biggleswade. We exchanged 579 reports, although I was rather generous with my report really because of the local SMPSU noise. Also heard was G3YXM who was rather weaker than Chris.

I am now continuing with WSPR beaconing and will run the beacon (TX and RX) through the night for the first time on the new MF band. So far my best DX report is from Germany, but I would dearly love to be copied, if just once, by TF3HZ in Iceland. Haldor is monitoring and it is just about at (or just beyond) the limit of range with my 10-20mW ERP.  With QRP I have learned that nothing seems to be impossible with a bit of perseverance and good luck.

VLF amateur activity

There is a new VLF grabber at Darmstadt Germany that may be useful for 8.97kHz tests. It is at http://skmail.ikp.physik.tu-darmstadt.de/gvw/grabber.html. The grabber is primarliy there for VLF research into earthquake precursors.

Stefan DK7FC reports that the permit he has to use a 300m kite antenna expires soon, so he may try a further soon before that date.  Chris G3XIZ is still hoping to resume VLF tests once a new loading coil is wound. He is looking for a suitable (very long!) source of PVC covered wire.

G3XIZ TXing on VLF today

G3XIZ is active this morning on 8.9766616kHz and clearly visible on the G3ZJO grabber in Northampton. His signal was a lot weaker than the last few times for some reason. I think the difference is at my end.

My 50uW ERP signal at 45km on 137kHz in QRSS30

Chris G3XIZ has sent me a nice screen shot showing my QRP beacon signal a couple of days ago. The signal is in QRSS30 and as Chris says, certainly good enough for a 2-way QRSS QSO on 137kHz. Chris is 45km from me.

G3XIZ testing on VLF overnight tonight

Chris G3XIZ will be active on VLF again this evening and overnight on 8.9766616kHz although the start time is not yet known. My VLF on-line grabber is already on in readiness, as is the grabber at G3ZJO. Chris has recently been improving the match to his VLF loading coil and antenna and is working on a new variometer.

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.

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.

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.

Reports on 137.5kHz WSPR and QRSS3

In the last couple of days I have managed to get a couple of reports on 136/137kHz. Yesterday G3UUT copied my QRSS3 beacon and today G3XIZ copied the WSPR beacon. Neither represent any great distance - G3XIZ is 46km and G3UUT about 18km - but these are my first reports since getting back on the band after a few months of absence. ERP was about 10-20uW. G3XIZ was getting me at about -22dB S/N suggesting that around 100km may be possible on WSPR with the current kit (I did get a few spots from G3YXM at 148km last autumn with the same set-up), so I hope a few more stations in range can manage to detect me. I really must increase the ERP by 10dB: I have been saying this for too long and not doing anything about it!

VLF success at last for G3XIZ (37km on 8.97kHz)

Chris G3XIZ achieved some VLF success today when his 50m high balloon supported vertical driven with around 50W was copied at up to 15dB S/N by M0BMU at a distance of 37km. Mode used was QRSS600. This is a new UK record for an amateur VLF transmission and is the first confirmed "far field" radiated signal. Well done Chris.

M0BMU estimated the ERP as follows (from a posting to the LF-reflector by Jim):

"I made an estimate of the field strength of your signal by injecting a test signal at a known EMF into the loop antenna, and comparing with the level of your signal. The received FS at the strongest point (around 1330utc) worked out to be 1.8uV/m. Taking the distance between our locations as 37km, your ERP would have been 87uW. The SNR at best was around 15dB, making the noise level 0.32uV/m in the FFT noise bandwidth of 2.1mHz, or a noise density of 7uV/m per sqrt(Hz)


Assuming a 50m vertical wire (heff ~ 25m),  Rrad of your antenna at 8.97kHz would be 880micro-ohms. Assuming 2.62dB directivity for an electrically short monopole compared to a dipole, and Iant of 200mA, the calculated value of ERP would then be 64uW. So there is reasonable agreement between these two calculations, the difference only being 1.3dB."

Looking for G3XIZ on VLF this evening

G3XIZ is transmitting with 20W to his Marconi vertical on 8.9719kHz this evening from 2000-2200z. I am looking out for his signal with my loop into both Spectrum Lab and Spectran software. You can look on my VLF grabber to see if he is visible at all over here in JO02dg. At the moment all that is visible is a wobbly 50Hz related signal and my 8.760kHz QRSS3 beacon running on a dummy load. UPDATE: nothing copied and Chris had to close because of an antenna fault at 2100z.

Looking for G3XIZ on 8.9719kHz VLF

Looking for G3XIZ on 8.9719kHz - maybe a faint trace??

Between 2000 and 2200z this evening G3XIZ has been transmitting on 8.9719kHz VLF with his Marconi vertical and about 20W RF into it. I've been monitoring with my earth electrode antenna, a preamp/filter and a PC running Spectran on 0.17Hz resolution, but don't think I've seen any sign of him.

WSPR success on 137.5kHz

G3XIZ's 137.5kHz WSPR reports today

Chris G3XIZ has successfully received my QRPp WSPR beacon this morning on 137.5kHz. ERP is around 10-20uW from the class-E PA producing around 4-5W. This brings my total number of WSPR reports on the band to two with the best DX now 46km.

136kHz using the earth electrode "antenna"

This evening I was able to copy G3XIZ on 136.5kHz CW at 559 using my deaf (at 136kHz) FT817 fed from my 20m base earth electrode "antenna" used on VLF. I've made a recording and emailed it to Chris who is 46km away from me. Later this year I hope to transmit QRSS or CW on 136kHz, but the antenna needs some thought as I don't have much space.

82nd unique 500kHz WSPR report

This evening I got a new unique WSPR report, the first in 3 weeks, from Chris G3XIZ. This is my 82nd on the band. Chris has just started on WSPR and is likely to come on WSPR TX shortly. He is a very experienced 500kHz CW operator.

My first 2-way CW QSOs on 500kHz

This afternoon, just after midday, I worked Mal, G3KEV, in Scarborough for my first 2-way CW QSO on 500kHz. I gave him 569 and he gave me 529. Then at 4pm I was called by Chris G3XIZ who gave me 579. ERP at my end around 2mW.

136kHz Listening

Just heard quite a good signal (RST569) from G3XIZ on 136.5kHz CW. He had just worked G3KEV before 8am but I could not copy G3KEV (Mal). I made a recording which is on my website - quality not good as it was made with my Dell Axim pocket PC held next to the loudspeaker.