QO100 part 2

M0RVB

The reason I moved the dish was, as explained in part 1 partyl due to me wanting to send and receive DATV. Having sorted out the receive parts for the narrowband transponder the next step was to set up to receive the wideband one. the LNB was originally a 4-port device which has been modified to take an external 25MHz sinewave input on one of the ports thus leaving three free. I ran three runs of RG59 from the shack, one for the 25MHz feed and two for reception. So it was relatively easy to use the second of these to receive DATV.

I already had a Winterhill DATV receiver (see https://wiki.batc.org.uk/WinterHill_Receiver_Project ) and documentation for this shows how to configure it for QO100 use using two of its inputs, leaving the other two free for other purposes. A splitter combines the two 'top' ports, feeding power from the first port. With the Winterhill set up to send 18V it flips that LNB receiver to the right polarisation for the wideband transponder. QED.

And it just works. I did have to fiddle with settings because when I got the Winterhill I experimented with remote access so when turned on it simply ignored the attached HDMI display. On paper that was a case of editing the winterhill.ini file and setting BOOT=local. Buit it still did not work. I could see it had started VLC players but the screen was blank. The fix for this was to edit /boot/config.txt and uncomment the line #dtoverlay=vc4-kms-v3d. Rebooting revealed the our VLC windows with the top left showing the QO100 advertising video.

Tuning was another matter. There is a utility called QO-100 WB Quick Tune available from https://github.com/m0dts/QO-100-WB-Live-Tune/releases but this is a Windows package and I do not have Windows! Fortunately however it runs just fine under wine. This utility shows the occupancy of the wideband transponder and clicking on a signal instructs the Winterhill to display it. At first I forgot that when I added a receiver it needed me to specify the LNB voltage but once I worked that out all was well.

A screenshot of the Quick Tune utility
A screenshot of the Winterhill display on a Raspberry Pi showing 4 VLC windows with two having video content

I have yet to set up the audio but it all works fine.

The next step is to sort out the transmission side of things. That is for part 3 but will take me a little while yet.

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M0RVB

QO100 part 3

This part was going to be about the full transmission path but I am still getting the POTY and LDF4-50A line ready. Instead, I wanted to experiment with the SG Labs 13cm transverter. For the test the FT818 was dusted off and set to 432MHz FM so it would give a constant output when keyes. This fed the transverter, the output of which was put into a dummy load via a 20dB directional coupler that in turn fed a frequency counter. The output was giving 2,404MHz and was nicely stable over a couple of hours (not keyed all the time of course). When finished the transverter will be locked to a 10MHz reference from a GPSDO. The output power was around 18mW, again via the directional coupler, so about 1.8W. The FT818 was not set to full power and the PA, when finally installed has a maximum input of 250mW so some attenuation is still needed. Ok, so I have a full receive path for both transponders, I can decode FT8, hear SSB and see DATV. And I am now happy that I will be able to transmit once the PA and POTY are all in place. My next thoughts…

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M0RVB

QO100 part 1

Finally I had a chance to set up the QO100 dish on the side of the house. It was originally behind the harage at ground level which was not ideal as it was both a head-hitting hazard and an RF hazard, especially as I eventually want to be able to send not only SSB but also DATV which requires a higher power output than the 4W I had originally. I also wanted to copy the special GB2RS broadcast on QO100 which was scheduled for the 28th September, 2025. So, out with the scaffolding and up with the dish. That was the easy part. The disk elevation was already set so all I needed to do was point it in the right direction azimuth-wise. I nearly got that right using a theodolite app on the phone so with the aid of all relevant hardware I tuned it to max, for now anyway. It was rather amusing to have to set up a laptop and power supplies on the scaffolding as the last time I did that was at ground level. Cables came next - three runs of RG59, each around 12 metres back to the shack. These were very fiddly but…

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M0RVB

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…

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