New TX set up

  • Hello to all my new AMSAT friends! Hope some one can advise. I am setting up a QO 100 station, I am starting with RX only as it is supposed to be easy to set up. My starting rig is as follows: 80cm Opticum dish, modified high stability LNB, 12.5 volt Bias T, RTL SDR R820T dongle, SDR console v3.0.26, ASUS laptop running Windows 10 64 bit. Azimuth 149 deg, Elevation 26.2 deg. My QTH JO01fs.

    So all set up and NOTHING but noise on the lap top screen, tried moving the dish but no change, tried a new LNB, again no change. Any ideas?

    Screen shot attached.

    73 Phil G8PJH

  • Hello Phil; I think that Ulrich is pointing you in the correct direction, the chances are that you are not on the correct receive frequency. But could be a good few hundred KHz off frequency.


    I use a standard crystal controlled PLL LNB and it does not provide an accurate 9750MHz frequency, mine is around 9749.437MHz so just over 560KHz off and this will still drift over time and temperature.


    Not sure if you are able to try Gqrx on a linux PC or if that would work on Windows, or even SDR# should be able to help you, wind the Sample rate out initially to 2400000 b/s to give yourself the widest receive spectrum and have a hunt around moving up and down in 500 KHz steps until you find it and then fine tune.


    For example is is a current screen shot of mine centred on the middle beacon in Gqrx.


    Once you find the middle beacon knowing that the centre frequency of it is 10489.750 you can then a calculate better the offset of your LNB and then use that within SDR console as your frequency off-set.


    As I said this will change with temperature and sometimes quite quickly, SDR consoles needs to lock on to this to keep things stable.


    Hope this helps get you going.


    Another point give it a little more volts say 13.3 to 13.5 Volts to allow a bit of volt drop down the cable and through the bias T's. I thought the LNB's liked around 13 Volts?


    Adrian

  • Hi

    Thanks for the feedback, as you might have guessed this is my first go at satellite. A question, why use Gqrx or SDR #? Can I not just tune around with SDR console? Also, exactly how sensitive does the dish pointing have to be? Is it just a dot in the sky, or is there a tolerance? Thanks again for the help, steep learning curve!

  • Hi Phil;


    Just suggesting that you use something SDR# initially to pin point what your actual LNB offset is. SDR console needs this to be as accurate as possible to allow for locking to the beacon. I found if I was a couple of hundred KHz off on the offset then I could not find the beacon in the bottom waterfall to lock to. But yes using SDR console as a basic receiver at 740 ish MHz is fine, you should still be able to find it, I would just suggest initially that you get the widest spectrum you can to find it. It can be quite easy to find if you use get an idea from the sat finder page on https://eshail.batc.org.uk/nb/


    Looking at your first picture I notice you are not using SDR console as I expected, normally I would see a screen with the frequency across the top being in the 10GHz region using a receiver with the prescribed offset, then you have the opportunity to use the beacon lock etc.


    Adrian

  • This is an excerpt from our Wiki/Lexicon Antenna:

    To receive QO-100 you need at least an 85 cm dish and preferably 1 m or more for DATV and on the edge of the footprint. Learn how to aim your dish at the Es'hail-2 satellite on DishPointer. First select "25.9E ES" on the right and then "Your location". Then draw the direction line exactly to your location. Here you will also find the skew angle for adjusting your LNB. Now you should be able to easily align your dish and receive the first PSK beacon signals. You can now make fine adjustments using the beacon signal (Audio sample).


    Note: Do not look for the footprint of Es'hail-2, this is different from the QO-100 transponder. For Es'hail-2, you'll just find spot beams for its TV channels.


    Hope it helps. Good luck & 73

  • Thanks for all the suggestions guys, but still no luck. Thinking logically, I’m pretty sure there’s nothing wrong with the hardware, so all I can think off is the dish is pointing in the wrong place! Finding it difficult to locate QO 100, not finding it as easy as people make out.

  • Just one point worth noting that is not always obvious. The face of the dish will be close to vertical to achieve the required elevation. Don’t expect the dish to be pointing upwards.


    Positioning is quite critical. A couple of degrees out in either axis will loose the signal.


    If there are sky dishes on nearby houses compare yours with them. The direction and elevation will be very similar.

  • Hi,


    For pointing the dish if your mast is leveled vertically than for elevation you can use the angle scale which most dishes should have printed on the mount. It will bring you close enough. Than search for azimuth and after you find the sat do fine adjustments to azimuth and elevation to get the strogest signal.


    Just to try if your hardwere is working and assuiming you are on right frequency span you can just point the LNB in the direction of the sat. The LNB alone isn't very directional. So +/- 15-20 deg off the direction would still receive. You should hear the beacons and maybe also some strong SSB stations. The signals will be weak but you should hear them. I can elasily copy the lower CW beacon just with a LNB.


    Make sure you oriented the LNB in right polarization. For NB transponer should be vertical. If you mounted it in horizontal probably you won't hear anything. Than adjust it also for the skew angle which should be -19 deg for your location. This angle isn't that critical to be set very precise. Even 10 deg off you won't notice much difference.


    73 Andrej - s57rw!

  • Hi all,

    My dish angle scale doesn’t make much sense, when the dish face is vertical, the scale is showing 26 deg. , and the offset arm is 7 deg, measured with an iPhone incline level. To set the QO 100 elevation, I set the dish face exactly vertical, placed a straight piece of timber across the top and bottom edge, then using the iPhone level moved the dish upwards to 26 degrees. Does that make sense? Thanks.

    Phil

  • Hi Phil,


    You have a offset dish which is mostly used nowdays for SAT TV. Check on google difference betwen offset and prime focus dish and you will get the idea. Anyway your dish being offset type means when the dish faces exactly vertical means the dish is looking abt. 26 deg up (depends on the dish model but is here around). So trust the printed scale. If you used a level and pointed the dish at 26 deg means your dish is looking probably 50 deg up.


    Set it using the dish scale and than search for azimuth. After you find the sat make fine adjustments.


    After some time you will get practice. I can find the sat with a dish holding it in my hands so it isn't that hard :)


    Make sure also as mentioned above that you mount the LNB to vertical polarization -19 deg of skew angle. On the LNB flange usually is printed a angle scale. 0 deg on the scale is vertical than rotate it to -20 deg for your location. You will se this scale is quite rough but the setting isn't critical at all. Just don't be off by 45 deg or more :) Before messing with that you can set it to 0 deg and after you point the dish adjust. Better not to have too much parameters at one time...


    For 1st test you can check ask mentioned above receive with the LNB alone. You should hear the beacons, quite weak but you will if the rest of the setup is working properly.


    73 de Andrej - s57rw!

  • Hi Phil,

    If in your area the TV-SAT dishes are positioned on Astra 28.2 °, all you have to do is position yours in the same direction. Just a little bit to the right. If you have a small Satfinder, like this one in the picture, (6-10Euro) it will be much easier to find TV satellites. Once you are on the right elevation for small horizontal movements it will not be difficult to get to Es'Hail-2 / QO-100


  • Many thanks gentlemen. Interesting about the elevation angle, probably where I was going wrong. I set the azimuth today using the sun. Made a boresite for the dish arm, at my location today at 10.28 the sun was at 149 degrees azimuth, so lined up the boresite with the sun, so the dish will now be pointing at the correct azimuth ?

  • Hi Phil,


    Yes if you set the scale at 26-27 deg elevation and 149 deg for azimuth you should be in about right position. Of course you will have to make some fine adjustments by azimuth and elevation to find the right spot. Do it azimut and elevation separately by not releasing all screws wobbling the dish all around. You have to assume probably your mast isn't perfectly at 90 deg, the printed scale for elevation is more for indication and also you didn't point the sun exactly. But you are in the area so make small adjustments by few deg. Take also in consideration when receiving with a sdr dongle that it has some small delay. But when you move the dish if you are doing it slowly you will get it at the right place.


    Once you will fix it at right position you are done. Just make sure the mast is stable and not wobbling in the wind with a 80cm dish on it :)


    73 Andrej - s57rw!

  • Hi

    Success! Just been listening to some QSO,s on QO 100! I had the dish elevation set completely wrong as mentioned earlier, the dish is now nearly vertical. Also I under estimated how a little adjustment makes such a big difference in signal strength. Just got to figure out what I’m looking at on SDR console now! Onwards and upwards to the TX side. Thanks again for everyone’s advice, I couldn’t have done it without you all.

    73 Phil G8PJH