Today I carried out a test with my new simpler RX system for VLF/LF earth-mode "through the ground" communications, testing with a 5W TX into 20m spaced earth electrodes at 8.976kHz.
The new preamp is just a single MPF102 impedance converter feeding into a small,low cost, external USB sound card (£3) that feeds my baby Asus X101CH netbook (£172) running Spectran software to display the received QRSS3 signal. The external soundcard was only needed as I didn't have a 4-pin jack to use the audio-in socket on the Asus.
Tests were carried out at the usual test sites at 1.6, 3.6 and 6km as well as one further (unsuccessful) test at 6.2km.
In all locations, decent signals were copied, even at 6km. The little Asus netbook has an SD card running Readyboost and behaved perfectly well during the tests. Now, the whole system is very simple to deploy in the field to take measurements. The preamp is only tuned by the loop and its resonating capacitors (a capacitance decade box), so the very same preamp can be used right across the VLF and LF spectrum with a suitable receiver.
Today the weather was dry and has been for around a week now. I believe signals by earth-mode are stronger after a period of dry weather as the soil conductivity is lower. Results are as good, or better, than I have ever experienced before with earth-mode at 8.976kHz.
The next test will be to repeat this test at around 1kHz and possibly lower frequencies.I also want to try WSPR and repeat the tests at much higher LF frequencies around 72-73kHz. For the latter test, I need to build a simple down converter to audio.
The TJ2B 4-band SSB HF handheld is available direct from China for around £176 as a kit with all the SMA components already mounted on the PCBs. See eBay item number 271195721443.
Although I have not used them myself (yet), www.hamshop.cz has a range of interesting and useful parts and kits available for purchase by PayPal. They ship worldwide too. Check out the page in English. As far as I can see, the prices are quite reasonable too.
This morning I read a most interesting article about French cloudbounce and scatter optical tests using lasers. The article is some years old but makes a fascinating read. My own experience with clear air forward scatter at optical frequencies using relatively low powered red LEDs makes me believe that a LOT more is possible in this area. It is a bit like people saying, "UHF is only line-of-sight". Rubbish! With decent, easily built kit it is possible to copy QRP amateur signals over the horizon even at IR and visible optical frequencies.
This evening I noticed that the first user review of the Icom IC7100 has appeared on eHam.net. YB1FWO bought a unit in Japan and give it a 5 out of 5 score. I've not heard if this radio has appeared in the USA or European dealers. It was not priced a few days ago but I gather the UK price is just below £2000, so not a low cost product although it is a neat, multi-band (including 4m), multi-mode 100W radio.
There seem to be more people trying WSPR on 6m than in previous years. Prompted by Nick G4IKZ this evening I have moved from 10m to 6m and have spotted CN8LI (2113km) and been spotted myself by a few G stations. On 6m the Doppler shift on signals can be quite fierce and setting the FT817 accurately on frequency is a little more tricky: I have to set the FT817 to 50.29260 rather than 50.2930kHz to get the correct frequency spots. I assume my 12 year old reference oscillator in the rig is a bit off. On inter-G signals I suspect that the Doppler is a result of aircraft reflection. On more distant DX stations I assume it is as a result of E layer clouds moving around.
Doppler on transatlantic 6m multi-hop Es signals might be a killer - I can imagine reflection points moving around in the E layer - but if not, then WSPR would be a great way to check for transatlantic openings.
I'll leave the 2W WSPR to the co-linear vertical running overnight tonight and on a few further nights through June and July. We just need LOTS more USA and Canadian stations both monitoring and RXing on 6m WSPR.
Tomorrow morning, all being well, I hope to do a further test on VLF earth mode at 8.97kHz using my new Asus X101ch netbook using Spectran software and a simpler loop preamp on RX. Initially I'll test locally to check results are as expected before venturing further with the new (simpler and smaller) RX system.
Also, I want later to try TXing with a large, single turn, horizontal loop on the ground around the garden rather than the earth electrodes. On the basis that I am coupling into the ground and utilities, a horizontal loop might be as effective at coupling as the earth electrode antenna. A straight comparison of one against the other will be worth trying.
Just for a bit of fun I went on the 2m UKAC contest this evening with the FT817 to the vertical colinear from home, not the most ideal of antennas when everyone is running horizontal beams. Nonetheless, I managed 6 QSOs in just over an hour of operating. No great DX - the best QSO was just 47km tonight - but a bit of fun. The better stations were exchanging serial numbers in the 70s (at least) and I was hearing stations working GM, GW and F. The map shows my (meagre!) QSOs. Maybe in a month's time I'll erect that big wheel here at this QTH and we can compare results v. the vertical antenna.
My iPod Touch 4g battery, not easily replaceable, is now suffering from low capacity after being used daily for over 2.5 years quite intensively.
Of all the technology kit I have owned over the years, my iPod Touch 4g must rank as the very best. It gets used to surf the net over wi-fi, to communicate with our children and grandchildren when on holiday as well as for BBC iPlayer, music, videos, games, amateur radio applications and much more. Mine is the 8GB version but I see Amazon is now selling the 16GB 4th generation version for just £129, which is a bargain. I am sorely tempted to replace my aged unit.
This was news to me, but I just spotted a new, European made, high spec 20W SSB/CW 4m/6m transceiver from a company called Noble Radio on the 4m website at www.70mhz.org. To my eyes this is an ugly beast which resembles an old PMR radio, but what a good idea for a new VHF transceiver. Certainly in Europe a 6m/4m transceiver has some attraction for those interested in the lower VHF spectrum, if the price is sensible. Wouldn't it be nice to have a 4 band (10, 6, 4 and 2m) all-mode rig from Japan or China too sometime soon. There would be a market.
Does anyone know who Noble Radio is and in which country they are located? I have no idea about price or availability. Perhaps this is a "test the interest" concept model, rather like the Tokyo Hi-Power QRP radio of a few years ago. This was shown at a ham fair but never made it to market.
