Big Dishes


Chris Bartram G4DGU
 

I can't disagree at all with John.

I'm just staggering back onto 10GHz EME after a very long absence.

My personal philosophy involves the design and making of most of my own equipment. I draw the line at designing my own transceivers, simply because if I did that, I'd never get on the air! I also feel that the march of consumerism into our hobby is a very negative factor. For me, amateur radio is not about a 'mine's bigger/more expensive that yours' contest, but rather a means of continuing self-education. It has taught me a lot.

Having had a reasonably sized (2.4m offset) dish on 10GHz, I didn't feel that was was necessary or desirable when getting get back on the band from a QTH with a conventionally sized garden, and neighbours, rather than rolling Welsh acres and relative isolation as was the case before.

As John says, optimising a small antenna for good results on the EME path is a heck of a lot more satisfying than using an antenna which which I could detect significant Moon noise straight into the transverter, and was able to make my initial QSOs with just a few watts!

I wrote a note for 'Scatterpoint' back in the late 2010s suggesting that a QSO might be possible (using JT4) between 10W/1m dish stations. I was rather optimistic in my assumptions regarding the performance of JT4 at 10GHz (which was quite new at the time I was writing) but the latest WSJT mode, Q65, does seem to be approaching the required performance in practice. Certainly, as John will tell you, 20W to 1.1m is enough to work a 1.6m dish with a bit to spare - but it does require that 1.1m dish and its associated systems to be working very well.

73

Chris

G4DGU

Any fool can make EME QSOs with a big dish, the challenge with EME for anyone with half an interest in pushing technology is making QSOs with what you can build and fit in your garden and get past your neighbours.
My experience is that there are some REALLY badly set up big dishes out there, especially on 10GHz but if you REALLY work on the Engineering, an optimised small dish station will outperform bigger dishes run by those who just chuck a feed in to a big dish and don't even try to optimise it. There are plenty of those in the EME community. They do this quite innocently because they just find they can make QSOs without bothering to optimise. With a big dish, you have to do the mechanical Engineering really well but some don't bother with the radio part.

That said there are some extremely well set up big dishes as well, and you know when they're on!
Peter G3LTF (see my June GHz column) is a case in point.

If all you want is a lot of QSOs with little effort or to make more QSOs than everyone else take up HF contesting, not EME, unless you have a VERY big garden, no neighbours and shedloads of money.

Me, I prefer a few quality QSOs not just ANY QSOs