On the 11th of October, 2010, David VK3QM and myself completed some 47 GHz contacts on our very newly constructed transverters. Various distances were tried and we were able to progressively work up to 47.5km (a new VK3 record). At 0512z on 11th October on 47088.3 we exchanged reports of 51 both ways over the 47.5km path from a location in the Barabool Hills to near Mt. Mercer. Wx condx at the time were 23-24 degrees C and ~ 65% humidity. We were very pleased with the results and feel there were still some “km” in our systems.
Our transverters are 2 identical units consisting of a Kuhne mixer module, G8ACE OCXO at 122.250 MHz and DB6NT LO multiplier chains. The LO chain was built from kit form and the mixer modules came pre assembled with 170uW of power and a measured Noise figure of 6.6 dB. The antennas used were 25dB horns (120mm long) made from copper sheet.
Soon we hope to add 27dB more Tx power (approximately 20mW ) and a 1ft dish to both setups so we can try over greater distances.
Interestingly, David and I are very pleased with our “free running LO” stability on both bands. We were consistently where we expected each other to be and during our several 10min + QSOs we rarely had to “retune” more than a few 10’s of Hz! I am convinced that using free running LOs (OCXOs) has significantly contributed to our weak signal capability. The key is of course, to check / calibrate the frequencies each time before heading portable due to crystal aging and retrace.
Pictures of transverter: 2010
Pictures from October 2010 field operations ....... 47.5 km achieved.