Stake out on 481THz

481THz RX on tripod with optics.

In the daylight today I went to the RX site used in last night's unsuccessful over-the-horizon (NLOS) optical beaconing test. I've now marked out on the ground (with sticks and stones!) the exact direction to aim my RX in when I return for a second try, hopefully tomorrow night.

Yesterday it was so gloomy that I could hardly work out where to aim, so this now means I can be within a few degrees accuracy on initial set-up. I've also adjusted the aim of the TX beacon optics. Visibility for Thursday night is forecast to be "very good" with cloud cover according to my Met Office app, so let's hope it works OK tomorrow.

The RX and 100mm optics are shown above. Note that the upper tripod extension (below the tilt arm) is rarely extended as the whole thing is then too wobbly. I need a more sturdy tripod. Also, the low cost gunsight scope (bought for just a few pounds off eBay) is of little use at night (too little light) but very useful in daylight.

Mag-mount E-field probe on 8.97kHz

Just as an experiment, this afternoon I modified my mag-mounted FET drain tuned E-field probe to work on 8.97kHz. The last time I rigged an E-field probe on 8.97kHz and went looking for my earth-mode signal results were very disappointing wih just a couple of places within 2km radius where the 5W beacon was copied, but tomorrow morning I'll see how well (or not) it works. To tune the FET drain to 8.97kHz I just substituted the 137kHz tuned circuit with an 83mH Toko potted coil in parallel with 4n7. Tuning is reasonably sharp. Whether the car grounding will make a big difference we'll see in the morning.

Eddystone User Group

If, like me, you owned an Eddystone communications receiver at some point in the past then you may like to look at the Eddystone User Group pages. Here you will find lots of data on old receivers, links to data sheets and service manuals and a lot else too.

In my case I owned a Mk 1 EC10 receiver similar to the one shown here. This was state of the art in the late 1960s when it sold for £48. By modern standards it is a pretty rubbish receiver.

481THz over the horizon test: no success tonight

Weather this evening was not suitable for the tests, although I did try. I set up the QRSS3 beacon pointing out of my bedroom window using the local windmill as the aiming point. This is on the top of our small hill which rises about 15m. I then drove to a spot 3.6km away over the hill to look for the signal with my sensitive RX and 100mm optics using Spectran to display the trace. Unfortunately this time the slight drizzle and murk was just too bad and no signal was copied, although I've had good results in the past at a very similar spot.

In daylight I need to recheck my beam alignment at the RX location as it was sufficiently murky to not see the local landmarks used to help aim the RX last time. Despite panning across 45 degrees of aim nothing at all was copied of my signal. I shall repeat the test in better optical conditions.

For those interested, the 1W 10mm diodes are available from http://www.ebay.co.uk/itm/350347623711.  You get 10 pieces for £9.26 with free postage and they are very BRIGHT.

481THz optical tests over the horizon tonight

This evening I am doing my first "over-the-horizon" optical test this year. The main aim is to check performance with the new receiver and to see how I get on using the iPod Touch 4g running SpectrumView software as the way of seeing the QRSS3 signal. I shall also be taking the laptop running Argo or Spectran.

Latest receiver that seems more sensitive than my older RX

The receiver circuit is the one in Practical Wireless this month by Stuart Wisher G8CYW. This is simple but works well in darkness. I've added an interface to the iPod Touch 4g (a capacitor and a resistor needed to enable the external mic input) and changed the coupling caps and op-amp gain. Using just MPF102 and 2N3904 devices the results look good. The low noise op-amp may be overkill unless one uses super low noise FET and transistor stages too.

After the tests I'll post results in the blog.

40m WSPR with 50mW - best DX spot 6505km

Reports received with 50mW on 40m

Overnight I've been WSPRing with 50mW output on 40m using the Par 10/20/40 end-fed antenna down the garden.  The FT817 set to 500mW directly feeds a Telonic 10dB rotary attenuator set to 10dB attenuation, so no chance of radiation from a coax cable. The antenna is only about 15m long and just 5m average height above the ground. Results (see above) have been very pleasing with best DX report from the USA - K9AN at 6505km.

Bug keys

Kent twin paddle key

Although not a frequent or very good CW operator, I do like to try QRP CW from time to time, usually with a straight key I've had for over 40 years. With rubber stamp QSOs on HF I can usually manage OK. The problem comes when people ragchew and I lose concentration!

Some years ago I bought a beautifully made Kent paddle key but I've hardly ever used it because I kept making mistakes. So, today I dug it out and decided to persevere with it on 40m CW. I managed a nice (unexpected) 2-way QRP QSO with Rick DK4QK who, despite my sending, managed to copy everything. Later I worked DM0E on 2-way QRP as well, using the bug. Like all things, good CW comes with practice and use. Using a paddle key should allow me to send better and faster CW with a little bit more practice on my part.

So, if you hear me calling CQ on 40, 20 or 10m in the coming days on CW, and there are plenty of mistakes and extra dots, then you'll know who it is.

20m WSPR

As the weather is totally miserable I decided to sit by the fire today instead of doing any amateur radio building. In the comfort of the lounge I am watching the spots being sent and received with 2W to the Par 10/20/40 end-fed antenna on 20m WSPR. 20m is not a band I use much, preferring 10m, although conditions on 10m have nothing like matched the conditions close to past sunspot maxima.

Some decent range spots (TX and RX) despite lackluster conditions on 20m

Exchange rate changes and ham rigs

In recent weeks the pound sterling has declined quite a bit against the US dollar and the euro. Against the dollar it has fallen from around 1.62 dollars to the pound to around 1.51 to the pound. This makes purchases of rigs like the KX3 even more expensive here in the UK.

On the other hand, the yen has weakened from 125 to the pound to around 142 to the pound.  Expect some discounting of Japanese rigs in the UK incoming months.  The latest yen exchange rate suggests a new FT817ND should be less than £500 again soon.

Which major dealer will be really public spirited and pass on their savings to us the amateur radio public?  Martin Lynch or Waters and Stanton?

A PSK31 QSO

Well, the little grandchildren have gone back home to mum and dad so the house is very quiet (and tidy!) again. This afternoon I decided to do a bit of QRP on 20m as a change. First a nice 2-way QRP QSO with Emi IZ4RDX who was running 5W (me 2.5W) and then a PSK31 QSO with Luis EA3UV. Neither contacts were great DX, but fun.  For the PSK31 QSO I decided NOT to use those pre-prepared messages and instead just keyed in what I wanted to say as the QSO went along. It felt like a real QSO, which was nice.

Tomorrow I hope to get back to the optical beacon work, but after 4 days of (lovely) little grandchildren this afternoon I just needed to "chill" as they say.  The plan is to build a beacon TX that will allow a range of subcarriers and also continuous subcarrier transmission as well as CW and QRSS beacon messages. I hope to get out "over the horizon" looking for the signal later in the week. Watch this space - literally if you are nearby, HI.