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.

My first 4m QSO this evening

Using my 70MHz homebrew transverter I managed my first ever 4m QSO using my own callsign this evening. I worked G6ALB on 70.2MHz SSB first and then we QSYed to 70.26MHz for an AM and an FM QSO. Reports both ways over our 3km path were fine even though we were cross-polarised. We invited others to join us, but no-one else was about. Years ago (1968) I did work ZB2VHF on 70.26MHz AM when running 4W from our university club station G3OUL.

Signs of springtime

My wife Lis with the snowdrops and aconites

Today my wife and I went for a walk to a quiet spot not far from here where we go every year about this time. At last there are signs of spring in the air with masses of white snowdrops and yellow aconite flowers. Winter is nearly done.