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.

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.

ARRL contest and re-erecting my X80 vertical

SRC X80 multi-band vertical

This next weekend is, I believe, the big ARRL DX contest and, if 10m is open, a good chance to work some transatlantic DX on this and other higher HF bands. I propose to re-erect my X80 vertical multi-band antenna in time for this contest and see what I can work with QRP. Also, another local, Ted G4NUA,  is keen to get back on 10FM, so a vertical may be better for local 10FM operation. 10m FM was good fun some years ago but activity very low these days, at least around here.

The Tenbox - name chosen

Thanks for the suggested names for my 10m DSB project. The one that wins is the Tenbox, which is the logical name following on from my earlier AM transceiver projects called the Fredbox (2m) and the Sixbox (6m). The Tenbox is just right - a small box with a complete, yet simple, 10m sideband transceiver inside that should be completed in the next 4-6 weeks.

There will be no progress now for a week as my little 3 year old grandson is here to stay and he sleeps in the shack bedroom. Maybe I will teach him a little more CW.

More work on the 10m DSB rig

Today I continued breadboarding the TX strip of the 10m DSB transceiver changing the single balanced mixer to a broadband design and adding/changing stages in the driver and PA. After the mixer, the driver/PA design now has 2 transistors and 1 FET PA with an output of around 1W pep. This is not enough. My aim remains at least 2W pep either from this line-up (with an IRF510 PA) or with a different PA.

Incidentally, I need a name for this rig. I used the name "Tenner" for my 10m CW transceiver, so what shall I call this one? Please give me some ideas! DSB10? Sidebander10? 10phone?

10m DSB rig progress (some)

Today I spent a little time on the transmit strip of my 10m DSB transceiver project. I started with the single balanced mixer using a T50-6 (yellow) toroid tuned to 10m, with LO injection from a signal generator and LF via a small audio preamp from an audio generator. For now I used a 1kHz tone to ensure drive levels were OK. Output is currently 20mW pep with 2 small 2N3904 linear stages following the mixer. To reach a useful RF level I therefore need another 20-23dB, easily done in two more stages. This would take me to around 2-3W pep.

HE3OM on 137.7kHz this evening

HE3OM (Switzerland) is currently active during February using an old broadcast antenna 125m long vertical. Signals in Europe are very strong despite an ERP of just a few watts. This was the QRSS3 copy this evening using Spectran and receiving on a pair of untuned earth electrodes 20m apart directly into the FT817 which is deaf at 136-137kHz, i.e. no matching and no preamps.

70.210MHz test with M0AFJ

M0AFJ's 4m CW at 75km tonight

This evening I did a test with M0AFJ in Milton Keynes about 75km west of me on 70.210MHz SSB and CW. Tim was using 80W to a 5el and I was using about 800mW into my loft dipole. M0AFJ was quite reasonable copy at times (see Spectran image of his CW - about 20dB over the noise) but Tim thinks, at best, he just copied the odd fragment of my transmission. With 20dB difference between us the result was not unexpected. I appreciated Tim trying though as I have now copied 3 stations on the band G6ALB (3km), GB3BAA (89km) and M0AFJ (75km).

4m transverter schematic

70MHz (4m) 1W pep transverter

The schematic of my QRP transverter for 4m (70MHz) is attached here and is also available on my website. Can't promise there are no errors but this is close to the real circuit as implemented. If anyone fancies having a go at this please remember this is a starting point and some optimisation of components and tuned circuit values may be needed with spreads in parts etc. As far as I am concerned this project is now complete and I have taken it as far as I want to for now.