This is yet another description of a QO-100 transceiver project. There are so many descriptions already on the internet, the obvious question is, "why one more"? Well, there are a couple of reasons:

This transceiver arrangement is somewhat unusual in that the indoor and outdoor units are connected by a single CAT-5 UTP cable. No RF cables have to go through the wall, no separate power cables, just a single UTP cable. This was very important in my case, as I couldn't get any new cables from my shack up to the roof. It works with (and has been calculated for) 15m of UTP cable; it will probably be just fine with somewhat longer lengths.

Despite my having done my homework diligently and in spite of my 35 years as an electronics professional, I found there were many pitfalls and things I hadn't thought of when I first put it together. Around half the items had to be redesigned and rebuilt. I hope that by publishing this, I might save fellow amateurs from repeating my mistakes!

Last but not least, the performance of the set-up is pretty good. I don't only say so myself, fellow hams on the air seem to think it's pretty good too.

The system is based on an ADALM Pluto with DJ0ABR's excellent AMSAT-DL QO-100 Linux SDR Transceiver software. An Othernet Bullseye LNB is used for reception and a set of amplifiers from F1OPA and DX-Patrol for transmit. The LNB and the ADALM Pluto are both locked to an 100MHz OCXO. I had initially left the option open to lock the OCXO to GPS, but its stability turned out to be so good that I never bothered.

The project is described here: https://www.qsl.net/s/sv1ui/QO-100TRX/QO-100_SV1UI.pdf.

Vy 73 de SV1UI