10m tropo reception

Been on 10m this morning using WSPR at 2W. During the last hour  the 5W signal of G3JKV near Dorking has been received several times at a distance of 123kms. Although there's some aircraft scatter visible on the signal, I think this is mainly tropo propagation.

Sub-9kHz NoV application and German VLF tests

Later this week I hope to submit my application to OFCOM for a special research permit (NoV) to test at VLF frequencies below 9kHz. Things are moving on at a pace in Germany with several stations gearing up to carry out some serious radiated tests (i.e. not by induction or conduction) and some new DX records below 9kHz are expected to be set. There is a lot of  discussion on the LF reflector about antennas, loading coils, loops and elevated loops using grounded electrode pairs. See also my webpage on this at http://sites.google.com/site/g3xbmqrp/Home/10khz

814kms on 500kHz with 500uW, a 10m halo and 5m of coax

This evening my 500kHz QRP WSPR signal managed to reach DL3NDR despite the antenna system being "downgraded" yesterday: the spiral top hat has gone and in its place is the 28MHz halo with 5m coax feeder. ERP is I believe some 6dB lower at around 500uW, yet it still gets this far.

New amateur DX record below 9kHz (VLF) - 12.1kms

Markus DF6NM has reported on the LF Reflector that he's been able to receive his test transmissions on 8.97kHz at a distance of 12.1kms. See http://www.mydarc.de/df6nm/vlf/vlf_12km.jpg. He has calculated his ERP at 1.3uW into his relatively small antenna with 1.4 Henry loading coil. The TX was a 35W car-radio audio amplifier. His RX antenna was 6m long and he used SpecLab with very narrow effective bandwidth. There are several others now experimenting below 9kHz, so this new record may not last long, especially as Marcus was using relatively low TX power. OFCOM is considering the issue of NoVs for <9kHz in the UK.

More 500kHz tests tonight

This evening I'll be running the 500kHz WSPR beacon into the 10m halo and its feeder again via the ferrite rod. Last night the best DX was to Holland. ERP is probably around 500uW.

More 10m antennas

Nick G4IKZ tells me he is using a Eagle Antennas 10m Moxon beam (see picture from the Vine site of this antenna). These are available for £149 and claim just under 6dBi gain and 38dB front to back ratio with a wide beam pattern. They are only 3.8 x 1.52m which is small for a beam with this amount of gain. I suspect Nick may have turned his beam my way now as the signal report on WSPR when I was running 1W was a massive +3dB S/N. Before I put up my horizontal halo I was lucky to get much better than -20dB when running 2 or 5W.

500kHz TXing using the 10m halo

Having taken down the 500kHz antenna and put 28MHz wire halo back up I tried TXing on 500kHz with it. I strapped the coax feeder inner and outer together and fed it via the ferrite rod ATU with a bit more inductance. First report was from M0LMH some 223kms away at -20dB S/N , so I still get out OK on 500kHz with now <1mW ERP. Also getting reports from G6AVK at 78kms. At 8pm I also got a report from PA1GSJ, so the 28MHz halo and feeder makes quite a respectable 500kHz antenna!

10m halo re-erected

After the winter using my pole for the 500kHz antenna, I've now replaced the 500kHz spiral topped wire with my Homebase-10 halo antenna for 28MHz that appeared in PW a few years back. Using G4IKZ 18kms away to receive my WSPR signal, I see the reports leapt up by at least 14dB, so it is certainly working well. I shall try the antenna and feeder (strapped together)  this evening to see how it performs on 500kHz. I'd expect it to be some 10dB down on the original 500kHz antenna.

10m tropo?

WSPRing on 10m this lunchtime I've been receiving G3JKV over a distance of 123kms. There is no sign of aircraft flutter on his signal, so I wonder if this is by tropo? He is, like me, only running QRP and this again illustrates how useful WSPR is at "winkling out" fleeting openings. I'll be swapping back to the 10m halo shortly.

USB powered direct conversion RX

G1INF has a neat idea on his blog for a simple direct conversion RX that is powered from the USB connection of a PC. His application was for LF reception but it would work equally well as the front end of a simple SDR for any HF band, replacing the loop with a bandpass filter. The audio output from the NE602 is connected to the PC's mic connector. Simples!