Breadboarded 137kHz 8W transverter (ERP 50uW from antenna) |
Simple 137kHz QRP transverter - click for larger image |
Simple QRP projects, 10m, 8m, 6m, 4m, FT8, 160m, WSPR, LF/MF, sub-9kHz, nanowaves and other random stuff, some not related to amateur radio.
Breadboarded 137kHz 8W transverter (ERP 50uW from antenna) |
Simple 137kHz QRP transverter - click for larger image |
80m WSPR with 5mW output |
Best DX 983km with 10mW in just a few hours! |
8.76kHz earth mode tests - best DX 5.1km and 4.75km |
"Today I received my SRP from Ofcom to carry out research and experiments on the 9kHz band. The NoV is effective immediately and expires on 10th January 2012. The allocated frequency, power and additional conditions are the same as for other UK 9kHz operators, ie. 8.700kHz to 9.100 kHz with a maximum of 100mW (-10dBW) e.i.r.p. I am not ready to transmit a signal yet but it will be quite soon. I will make an announcement through the usual channels.
73 Gary - G4WGT"
ATU for 136kHz. Antenna connected to top of ferrite rod |
DK7FC/P very strong on 136.8kHz CW today |
"I made an estimate of the field strength of your signal by injecting a test signal at a known EMF into the loop antenna, and comparing with the level of your signal. The received FS at the strongest point (around 1330utc) worked out to be 1.8uV/m. Taking the distance between our locations as 37km, your ERP would have been 87uW. The SNR at best was around 15dB, making the noise level 0.32uV/m in the FFT noise bandwidth of 2.1mHz, or a noise density of 7uV/m per sqrt(Hz)
Assuming a 50m vertical wire (heff ~ 25m), Rrad of your antenna at 8.97kHz would be 880micro-ohms. Assuming 2.62dB directivity for an electrically short monopole compared to a dipole, and Iant of 200mA, the calculated value of ERP would then be 64uW. So there is reasonable agreement between these two calculations, the difference only being 1.3dB."
WSPR reports 10m on 28.12.10 |
It was very pleasing to see my short article about the use of the ISM bands for QRPP beaconing in the latest SPRAT. In the UK this means 10...