10GHz on Cairnharrow GM/SS-191

Well I nearly made it! Yesterday I managed three 10GHz contacts from Cairnharrow, and it was only when I got back down that I realised I’d qualified the summit for SOTA because I had another contact with the 2m talkback station of another group I’d not completed a 10GHz contact with. Only four contacts in three hours then - but hey, it was worth it.

The weather forecast earlier in the week had been looking good for the weekend, and indeed Saturday was glorious. Unfortunately the UK Microwave Group 10GHz contest was on the Sunday, and the forecast was looking increasingly poor. However the morning was fine, and I got to my parking spot in glorious sunshine, loaded up (and it was a load) and set off up the hill. I took the 40cm dish hanging on the rucksack as I’d envisaged when I picked it up in Friedrichshafen a couple of years ago.

I must admit that I took a lot more rests than usual on the way up! A few little clouds began to come in, which was a help in keeping me cooler, and when I got to the trig point it was still sunny - though there were some ominous low clouds beginning to form. I set up quickly and soon had a text from Alan GM0USI who I’d set up a sked with, to say he was on site. I’d prefer it if we could do everything by “real” radio as opposed to using the mobile phone infrastructure, but hey, it’s there, you can’t un-invent it.

We had checked out the path between Cainharrow and Alan’s usual high perch on the Kilsyth hills, and although significantly obstructed we thought it might work, based on previous tests with other paths. In fact it was no problem at all - only 126km (previous best was 149km using my meagre 30mW) though over some significant hills (like Cairnsmore of Carsphairn GM/SS-038) south of New Cumnock. Alan runs considerably more power - 8 or 9W - so I can pretty well guarantee to hear him!

The next successful contact was with Geoff GI0GDP/P who was near Carrickfergus; only 98km, and probably line of sight (or close to it), I’ve not checked the profile yet.

Contacts were attempted with three other stations, but I could barely hear the carrier from two of them (running 1W and 5W, so they certainly wouldn’t have heard me) and heard nothing from the third.

However the highlight of the day was definitely my last 10GHz contact with Tony G4CBW near Stoke-on-Trent. He also runs a lot of power - more than 10W I think - to a sizeable dish. It was a struggle, but he eventually managed to copy a full contest exchange through the QSB on SSB; I could of course hear him easily, and we exchanged 56 / 51. That was a distance of 242km - my best DX yet on 10GHz. I think it’s probably close to the limit of what I’ll manage with only 30mW, so I will need to get on with building the 1W PA.

One of the unsuccessful attempts was with a station on Brown Clee - 290km distance, and rather more obstructed, though I could just hear a carrier from them. However we were using 2m talkback (easily) so I realised when I got down the hill that I was able to log a fourth contact and qualify the hill for SOTA. A pity I didn’t manage a fourth 10GHz contact, that would have given me a grin that would have lasted a week!

As it is, unless Jack GM4COX made his “microwave” contacts shown in the database on 10GHz (which I doubt as I know he’s not completed his 10GHz transverter yet!), my contacts are the first SOTA contacts on 10GHz from a GM summit!

I’d been operating in the mist for some time, but it cleared as I was packing up, and the walk back down was very pleasant. The pack felt a lot lighter!

What really pleases me is that this 10GHz stuff can be done with what is really minimal (and very cheap) equipment. My 10GHz receiver is an almost unmodified satellite LNB (as far as the mixer) which I picked up for a pound at Norbreck a few years ago, and the transmit side uses amplifiers from some surplus boards, which cost me a total of three euros! The dish cost me 4 euros I think. The most expensive bit 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 - see the photos I’ve just put on SOTA Flickr, or on my website. My FT-817 is the IF rig (and 2m talkback rig) though one day I hope to build a home brew driver for my microwave transverters!

So come and join the fun on 10GHz - I’m now wanting some S2S 10GHz contacts! Look out for the new kit from Chris Bartram GW4DGU http://www.chris-bartram.co.uk/

  • you’ll find the basics there ready built for somewhat less than from certain suppliers overseas :wink:

As I’m currently demonstrating, you can get started really well on 10GHz with very little Tx power indeed.


In reply to GM8OTI:

242km on 30mW - that’s amazing! 10GHz really is excellent.

Hope to be on for the next one.

73 Richard G3CWI