GM8OTI/P with his portable 10GHz rig on Cairnharrow,
Report & photos by John Cooke GM8OTI.
The first UK Microwave Group 10GHz contest of the year on Sunday 26th May gave LRS member John GM8OTI a chance to try out his home brew 10GHz transverter from a hilltop. He chose Cairnharrow, near Newton Stewart in Dumfries & Galloway in southwest Scotland as it has an excellent take-off over the Irish Sea, and is also a SOTA (Summits on the Air) summit.
The weather forecast earlier in the week had been looking good for the weekend, and the Saturday was glorious. Unfortunately the contest was on the Sunday, and the forecast looked increasingly poor. However the morning was fine, and John got to his parking spot in glorious sunshine, loaded up and set off up the hill. He took the 40cm dish hanging on the rucksack as envisaged when it was bought in Friedrichshafen a couple of years ago.
The path between John on the summit of Cainharrow and Alan GM0USI on his usual high perch in the Kilsyth hills had been checked out in advance, and they thought it might work, based on previous tests with other paths. In fact it was no problem at all - only 126km (John's previous best was 149km using a meagre 30mW) though this one was over some significant hills (like Cairnsmore of Carsphairn) south of New Cumnock. Alan runs considerably more power - 8 or 9W - so John can pretty well be guaranteed to hear him!
The next successful contact was with Geoff GI0GDP/P who was near Carrickfergus; only 98km, and a line of sight path.
Contacts were attempted with three other stations, but John could barely hear the carrier from two of them (Brian GM8BJF/P running 1W from the Lang Whang, and Mike at G3ZME/P with 4W at about 290km, so they were not likely to hear him) and he heard nothing from Eddie G0EHV/P over a highly obstructed path.
The highlight of the day was the last 10GHz contact with Tony G4CBW near Stoke-on-Trent. He also runs a lot of power - more than 10W - to a sizeable dish. It was a struggle, but Tony eventually managed to copy a full contest exchange through the QSB on SSB; John could hear him easily, and they exchanged 56 / 51. That was a distance of 242km - John's best DX yet on 10GHz. He thinks it's probably close to the limit of what can be done with only 30mW, so wants to get on with building his 1W PA.
John with his entire portable 10GHz station in backpack.
John had been operating in the mist for some time, but it cleared as he packed up, and the walk back down was very pleasant. The pack felt a lot lighter!
What pleases John is that 10GHz operating can be done with what is really minimal (and very cheap) equipment. His 10GHz receiver is an almost unmodified satellite LNB (as far as the mixer) picked up for a pound at Norbreck a few years ago, and the transmit side uses amplifiers from some surplus boards, which cost him a total of three euros! The dish cost him 4 euros. The most expensive part of the transverter is the local oscillator, which has a few new components (including a tiny 20MHz TCXO module) but probably only cost about 10 or 15 pounds altogether. Currently it's all built into a box which originally held a video and DVD recorder. John's FT-817 is the IF rig (and 2m talkback rig) though one day he hopes to build a home brew driver for his microwave transverters!
As John is currently demonstrating, you can get started really well on 10GHz with very little Tx power indeed.