Posts by DD4YR

  • HELI2400

    So please, my dear friends, even if we are just amateurs, our goal should be to reach our opposite with the main lobe of our transmit power to be as effective as possible with radiant power ...
    And that includes clean radiation characteristics of our antenna systems ...

  • decoder for unknown signal ?

    Yes, I can confirm KG-SSTV and also EasyPal.

    Both digital picture transmissions ...

    Center activity on 625.

    I´m one of the transmitting (and receiving) stations .... ;)

    Any questions?


    73s de Robert

  • UPLINK - PATCH VS HELIX - what's better

    Quote from DC2TH

    Shure, pointing to dish is not perfect.

    Wolfgang, tnx for detailed report of your equipment!


    I would be interested to know how far the focus of 2.4 GHz and 10 GHz differs. That would be easy to test if you focus your 2.4GHz uplink and control the 10GHz downlink via web SDR.

    So we get a result: is there any measurable difference, and if so, how much is it ...


    73 de Robert

  • UPLINK - PATCH VS HELIX - what's better

    Quote from DH5DAX

    May I call you Schrödinger's Ham? ;) You are right and wrong at the same time.

    ... nice :-)


    but true. We need the confirmation by experimental ... you did it.


    Now the only problem left is that the stacking of 2 antennas means that the E-diagram is only half as high as the H-diagram, which leads to a non-ideal illumination of a round parabolic reflector, right?


    Btw, the the example with the 4 LNBs was a joke ... We know that the profit of a parabolic system comes from the reflector surface and not the gain of the Feeds ...


    73

    Robert

  • UPLINK - PATCH VS HELIX - what's better

    Matthias,

    I do not think so. They will act as an array, but each helix has its own lobe of radiation.
    stacking antennas results in a doubling of the antenna area in the simplest case, thus also a gain of 3 dB. The distance between the antennas is chosen so that the 3 dB opening angle in the radiation pattern does not disturb anymore.
    As long as the signals are sent on their way in parallel, you will receive a correspondingly focuised 3 dB profit at the receiver.

    But, sent over a parabolic shaped reflector the lobes go apart and sprinkle ....


    For a common focus of the array on a parabolic reflector I lack the physical justification, but I like to learn ... (stacking 4 LNB´s and gain rise up 6dB ? :-) )

  • UPLINK - PATCH VS HELIX - what's better

    Thomas, here is the same offset problem as with the multi-feed holder ...

    you can only operate one satellite from the focal point ... the two helix are out of focus and will be blasting past the satellite with the main lobe ...

  • LNB Skew on Cassegrain

    If you can select the frequency , Symbolrate and FEC : yes


    Broadband searching does not work ... else you want to search for BADR4 Satellite, its near Es'hail 2.

  • WLAN grid antenna from WIMO suitable?

    Quote from DH5DAX

    and it is almost perfectly one S-unit down as expected by calculations.

    Hi, one S-unit are 6 dB. Can you try measure with SDR and look for SNR by the same bandwith?

    6 dB means you need 4 times more TX power to get the same RX level?


    And, what was the expected calculated level?



    73 Robert

  • usual equipment ?

    Quote from DL2NED

    I was thinking to start with 10 Watts. The transverter is installed very close to the feed just 2m high quality cable.

    Is this too much?

    Hello Martin,

    I think 10 Watts on the feed of a 1,2m dish is to much by using a cw carrier.

    I have a solid dish with 1,2m, 1 Watt TX power produces a strong signal about 20 dB over SN.

    I am interested in your results. Please report here :-)
    I wish you success!


    73´s de Robert

  • Multifeed holder

    Hallo Thomas,

    der Muldifeed Halter ist aus meiner Sicht der falsche Ansatz. Es kann nur eine der beiden montierten Antennen im Focus von einem Satelliten sein. Mutifeed Halter sind für den Empfang von 2 Satelliten, die auch noch einige Grad auseinander positioniert sein müssen, gedacht.


    Gruß

    Robert


    Hello Thomas,

    The Muldifeed holder is from my view the wrong approach. It can only be one of the two mounted feeds in the focus of a satellite. Mutifeed holders are intended for the reception of 2 satellites, which also have to be positioned a few degrees apart.

    greeting

    Robert

  • Umbau OCTAGON OPTIMA LNB auf TCXO

    Aber die "Aufheizzeit" des LNB nicht vergessen! Einschalten und betreiben geht nicht. Je nach Typ braucht das schon mal ne halbe Stunde bis der LNB-Block durch die Verlusstleistungen in der Temperatur stabil ist. Wetter- und Raumunabhängig ist so ein System nie stabil.


    Im Moment haben wir noch viel Platz auf dem Tansponder, aber mit zunehmenden Betrieb sollte man nicht mehr mehrere hundert Herz während den Durchgängen driften und in andere Verbindungen hineinwandern ....

    Betrifft auch die Senderseite! Und, da wird es erst während dem Senden warm und die Kisten beginnen zu driften.


    Interessant, wenn man dann beobachten kann, wie die ein oder andere Station seinem rennenden LNB den TX nachdreht, oder umgekehrt.

    Das kann dann nicht mehr zielführend für uns sein denke ich.


    Im Endeffekt erwarte ich schon, wenn jemand seinen TX in Betrieb nimmt, dass er auf der vorbestimmten QRG sendet und sich nicht erst auf dem Transponder suchen muss ... (wie man immer wieder beobachten kann)


    73´s de Robert