Posts by DH2VA

    not ANY TX power... only up to its directivity if inserted the correct way around. I would guess maybe 20dB (?) in reverse direction. If you add another 20dB as plain attenuator (which a LNB with its huge gain might easily compensate) you have 40dB of protection for the LNB again accidental TX.

    Sorry for the confusion.. we planned this for quite some time and got this now arranged with the satellite operator. The motivation for this is same SNR for all >60cm as noise and signal will go down in parallel. Indeed, 60cm dishes should still see some 4dB transponder noise remaining.

    A first for hamradio satellite operators: we will have our first solar conjunction nearing.

    The Sun will pass behind the satellite and generate a lot of radio noise in our receivers.


    The exact time and date will vary according to your location, but for me here (QTH Zuerich, HB9) QO-100 will pass in front of the sun next Sunday (March 3rd) on 10:21h UT. Only 0.2 deg Offset so well within the 1.xx deg of my dish and the 0.5 deg apparent diameter of the sun.

    Expect apparent transponder noise to drop.. reason of course will be system noise temperature rising. Looking forward to all your observations!

    DK1MG isolators and circulators are very close to each other. Lets start with circulators: they have typically 3 ports arranged in a circle and RF can only go in one sense of direction: for example from port 1 to port 2, from 2 to 3, from 3 to 1.. Isolators now have a fixed 50 Ohm terminator at port 3. So assume the PA is at port 1 and the antenna at Port 2. Any reflected power from a mismatched antenna will go to port 3 instead of propagating back to port 1 (PA). Therefore the PA is protected from any mismatch caused by the antenna.

    Hi Hans-Jochen,

    sorry for not getting back earlier.. I have a lot of things to take care right now, both qrl and for QO-100. Wouter Jan is right about everything.. and my unit is the same with the exception of the 24V label. Mine is running on 12V (PSU was included) and while it might run on 24V as well, I never tried. The empty spot is actually space for a circulator (you would need to find the correct type) and a 50 Ohm terminator next to it. But probably an external isolator is easier: PE1RKI

    short explanation: for a offset dish which tend to have large f/D (0.6-0.7), a feed with more directivity is required for proper illumination. So go for a helix.

    For a prime focus dish, which mostly have deeper f/D (0.3-0.4), the feed needs to illuminate a wider angle. Helixes need less windings here for this wide angle but then fail to generate proper circular polarisation. So here, the patch has an advantage.

    Thank you all for a mostly well behaved day 1!

    Please send in user reports with the following information (if available):

    • RX antenna diameter
    • NB noise floor increase
    • TX antenna diameter
    • SSB RF power


    We are trying to determine the useful uplink power as some stations are using way too much of it. This will help us in fine tuning the settings and improve performance for all.


    73 de Doha!

    Achim DH2VA


    PS: we are getting any news out as fast as we can but we are only three persons here (DB2OS, DG5NGI and myself) and we can either work or post.. :)

    As mentioned, the aluminum plane is close to the helix but not touching it and serves as a matching element together with the coppler fane soldered to the center conductor of the N socket. Not fully optimized (you are looking at the engineering model so to speak), we have four 'flight models' which are nicer looking, fully tuned up and distributed to the involved persons. If I understood DL5MLO correct, return loss at 2.4 GHz is in excess of 20 dB.

    Another helix feed. Design by DJ4ZC, CAD and construction by DH2VA and final alignment by DL5MLO. If enough people believe, that the construction is compatible with hamradio, we could do another journal article..



    Hi Chris, and welcome to the Forum!

    Some more info: DVB-S2 is less demanding in terms of power than DVB-S, so we do recommend DVB-S2. Also most OMs will probably use reduced BW DVB-S2, as noted by DG8KD so the best way (IMHO) is to get a Minitioune as it is the most flexible solution on RX. You need to become BATC member to order one, but the fee is small and it's worth it.

    For non-hamradio reception, you are probably out of the main beam of Es'hail-2 so if you want to watch the regular programmes, you can go with a standard satellite receiver but probably need a big dish..


    73s Achim

    I think I have seen aluminum foil covered mesh already. Electrically, this is fine, as long as you keep close to the desired shape. It might be more of a mechanical problem though, especially when wind comes into play (prevent it from tearing apart).