QO100 DATV attempt

M0RVB October 13, 2022

Well this got off to a bad start! Ahead of my plan to move the QO100 disk so I can get the electronics in the loft rather than the garage I wanted to test out the Winterhill box to see if I could pick up any DATV on the wideband transponder.

The Winterhill box generates the 18V necessary for the LNB so in theory it was just a matter of pulling the coax feed from the bias-tee in the garage and putting that into the Winterhill. That done, I could see the occasional signal but never a picture.

Now, I had noticed that the NB beacon strength had dropped a while ago so today I decided to adjust the dish in case it had been knocked. That snowballed! I needed a laptop so I could see the signal strength while at the dish (remember the dish is on the garage wall currently at about 6 foot, so easy reach). Of my two laptops one is a Mac and had no SDR software, the other a Samsung Netbook running Ubuntu and terribly slow. I tried setting up several SDR packages on the Netbook and failed miserably. At this stage I need to state that after a lifetime working in IT and solving problems I now have no time or patience to solve my own, so if something fails it goes to the bin!

So, the Mac. CubicSDR refused to even think about installing. I found SdrDX which works with the USB Funcube dongle amongst other, mainly networked things. This worked just fine.

Mac out on a lab stool in the shade, SdrDX and the Funcube running, the bias-tee in the garage powered up, a cable fed out the garage back to the dish and into the Funcube... fortunately it didn't all fall over and actually worked. So I adjusted the dish but only gained a couple of dBm more than before no matter what I tried. Oh well...

Back inside and plug the Winterhill in. Back upstairs to the Windows PC and now I see locked signals but just not enough signal strength for a picture.

I wonder if the LNB is full of spiders...

Anyway, now the QO100 kit in the garage is in bits I can't transmit so it can all stay as it is. My next plan is to remove the POTY and install an LNB and see if that gets me any DATV pictures, otherwise I am a bit stuck. The 1.2M offset dish has a clear view of the sky and should be ideal - it worked just fine for SSB on the NB transponder. I never got round to sorting out a GPSDO input for the Pluto but I am about to get a SG Labs 3cm transverter and plan to use an actual transceiver for tx once the dish is moved.

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M0RVB September 22, 2020

QO100 success

Got myself a Heil headset for the laptop as the built-in mic picked up room noise. So, I figured it was time to try a QSO on QO100 even with the floating (frequency wise) Pluto. And - success! I had a short QSO with a German station. Just waiting for some small signal diodes to arrive before I glue the GPSDO output to the Pluto. There is a modification that involves removing the 40MHz TCXO and connecting an external source but the Leo Bodnar GPSDO output is 3.3V, too much for the chip in the Pluto. The mod involves two diodes in antiparallel to earth, plus a capacitor between the Pluto chip and the diodes, and another between the diodes and GPSDO. Hopefully that will work and the surgery on the Pluto does not consign it to the scrap pile! The GPSDO I have has two outputs, one 25MHz to the LNB, and one 40MHz for the Pluto. I still need to sort the dish as signal strengths are still below where I expected. I am also concerned at the filter/pre-amp because it does not draw as much current as it is supposed to - it works but I wonder…

M0RVB September 16, 2020

QO100 sort-of success

Overcast today so I made time to try to align the dish a little better. One long Ethernet cable got the laptop under the dish and with SDR Console looking at the beacon I did manage to peak it a bit but I think I can do better yet. Oddly, no amount of moving the POTY in or out or skewing it made any noticeable difference. I did note however that the rain cover I made only makes a tiny bit of difference. The sky is a little overcast today so maybe signals are down because of the cloud cover. Anyway, I made a test CQ call and could hear my voice coming via the WebSDR nicely, so I made a couple of CQ calls but got no reply. I think I chased everyone away because after this there was very little activity. So, at least I know I am getting out and so a success at least in part. One thing though, the tuning is going to take some getting used to yet. The basic frequency conversion between the 10GHz band, the 2.4GHz transmit and 739MHz receive is 10GHz - 9750 = 739MHz rx frequency, and 10GHz - 8089.5…

M0RVB August 6, 2020

More QO100 progress...

After ages I finally made a rain cover for the POTY and led cables into the garage. Big delay there because the garage was a tip. It still is a tip, but the mess has been rearranged so I have access to the air brick where the cables come in! It's nice that when they built the house in the 1930's they put an air brick right there knowing it would be needed for a satellite dish... The rain cover is made from a sheet of plastic that came out of a smashed LCD monitor. I bent it round a bit of 110mm drain pipe using a hot air gun. it didn't quite come out as intended but it's near enough. The front is from the same piece of plastic and is epoxy glued on - yes there is a gap where the glue was less gluey, I'll fix that later. Nylon threaded bar and nuts hold it in place. And it rained an hour after I made it so it does actually work. After all the messing about everything still works. There is a nice box on order to take the gubbins - ok, the Pluto, bias tee, Leo…