QO100 portable receive system

It is our local club(s) rally on Sunday. ESWR has been running for many years and is the product of several local  clubs.

I seem to have been given the job of organising the UKuG guest interest group stand. I’m a bit surprised as I am no longer the Group Chairman and not even on the Committee this year. However..........

I have asked Jason, G7OCD, to bring his portable QO100 uplink system that he has demonstrated at several local clubs. To save effort his demos have usually used the web SDR, located at Goonhilly, for receive.

I felt it more appropriate that we demonstrate a ‘real’ portable downlink at ESWR. To that end I have been  busy.

Earlier this year I bought a portable ‘caravan’ satellite dish and stand. The dish is an offset 45cm steel unit and fits to the tripod stand. Instead of the original low quality, low cost, LNB, I decided to use a Gooby LNB (£5.60 each on Amazon). These are 25MHz crystal controlled PLL LNBs.

Obviously, the crystal in the PLL is of insufficient quality to provide good stability when mounted out in the open on the dish.

I decided not to use an external 25MHz reference, like I use in my home station satellite system. Instead I decided to try the beacon locking system now incorpoated in several pieces of software. I decided to use SDR Console v3.0.9

My initial attempts to run this version of SDR Console on my now elderly Sony Vaio laptop resulted in the program freezing, so I was starting to think about running unlocked after all. Sunday is getting close.

This evening I decided to try the program one last time and to my surprise and delight, it worked first time. I still don’t know what I was doing wrong previously.

With SDR Console I select ‘geostationary beacon’, then follow the instructions and the software locks on to the PSK beacon and stays there when I tune away to listen to stations. It is not foolproof and does still show some drift, although none of any consquence in the time I was listening. Some of the drift may also have been due to the reference in the RSP2Pro SDR I was using at 739MHz, also contributing to drift. Inam goingbto check that my locking the RSR2pro usingbits external reference input.

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My laptop drives the RSP2Pro and supplies its voltage via the USB socket. The Gooby is powered from a portable 12v 12000mA/h lithium pack (Lidl) and seems quite happy. I use a protected-against-short bias tee to supply the LNB over a single coax.

Now, I hope, with Jason supplying the 2.4GHz uplink, we will have a working 10GHz downlink to complement it to show rally visitors all about QO100.

The gazebo and table and chairs are being provided by other local  club members, so I don’t need to worry about them!

73 de Sam