• Official Post

    It looks like Octagon is receiving a lot of requests from potential QO-100 users..

    To prove that the LNB actually has a PLL with quartz crystals they now have images of an openend LNB with the description :):thumbup:


    Anyone tried this one?

    I'm wondering why they have now actually 2 quartz crystals / PLLs on the Twin..

    [Blocked Image: https://www.octagon-germany.eu…in-green_octagon-2019.jpg]

    • Official Post

    DB2OS that is for both seperate..nice design.. will order some...:thumbup:;)

    We will be very interested to hear your first results from first testing..

    I wonder why they have two of them, usually they have only one oscillator and Xtal for both.. but maybe a matter of the used chip set.. at least we can use different IF with external remote reference clocks on both outputs :D

  • Ja ja ja , wir weinen alle nach ....den guten Octagon Twin LNB Slim OPTIMA Model: OTLSO "3D logo" mit zwei getrenten oscilatoren und zwei getrenten output. Laut Octagon Juniorchef es wird diesen Type nie mehr geben ( warscheindlich weil sie in Hardware mit anderen konzept doch mehr Geld einsparen können ).

    Ich hatte vor drei Jahren grössere Mänge Octagon OTLSO auf risiko eingekauft , leider immer noch zuwenig wie sich in Januar 2019 herausgestelt hat , ende Januar waren alle weg !!

    ....alle weg "dachte ich" , heute beim aufreumen sind 4 Stück plötzlich auf Tageslicht gekommen , noch original - nicht geöfnet - nicht umgebaut , warscheindlich habe ich damals sie auf Seite gelegt als reserve.

    Ich werde sie so wie sie sind noch unbenützt zum Flohmarkt nach Eggenfelden bringen , der einer oder andere wird sich sicher drüber freuen.

  • Has anyone tested one of these Green on the satellite? I’ve just got one from Amazon, the single model, and it’s quite chirpy if compared to the good old Octagon one. Now going for modification to inject frequency ref, but I’m a bit sceptic... if it’s already chirpy with quartz, could it get any better with an external ref, no matter how clean it is? Unless the problem is with a bad quartz obviously...

    73 de iz2eeq

  • Last weekend I modified the Octagon Twin LNB Green. The main problem is that the version with the two cristals that the original poster added here is no longer available. Most of the versions sold today use only one central Xtal for both PLL sections of the LNB.

    Since the idea was to use this LNB for DATV and for NB I modified it to have one output working with the internal Xtal reference for low phase noise (important for DATV on the WB transponder). At the same time I wanted to be flexible regarding the connected DATV RX and therefore it was desireable to have an output in a frequency range able to be received by am ordinary SAT TV RX.

    On the other hand I wanted to have good stability by means of external stabilisation for the NB transponder.

    Based on the good experience with my VENTON LNB single cable inyection solution (invented and heavily promoted by Remco PA3FYM) my target was to have the same advantage with this LNB.

    So I had to come up with a creative solution to cover both use cases - optimized for WB and for NB at the same time.... :)

    Here is what I did:

    The one side of the LNB is running the PLL chip on a 24 MHz Xtal (original 25MHz Xtal was removed with hot air gun).

    This results in an IF frequency for the WB transponder of around 1130Mhz...(+/- Xtal tolerance)

    To avoid the other PLL being fed also by the 24MHz reference part of the Xtal PCB traces were cutted and partially removed.

    (see photo)

    The rest of the circuit is the typical PA3FYM approach. Cut the power trace from the F connector to the meander line and 330 ohms resistor leading to the voltage regulator. A 120pf+330nH parallel circuit blocks the 25MHz reference but lets the current pass to the voltage regulator to power the future "NB transponder" section of the LNB.

    Then only add a 120pF + 330nH LC resonant circuit as a filter for the 25MHz reference and use a short enamelled wire towards the inyection point of the PLL dedicated for the NB transponder....

    That"s it...now one side works for NB (with 25MHz reference injected in the shack via one of the many diplexer / triplexer circuits found here on the forum). And the other side works well for good quality DATV reception.

    Hope this will be useful for you.

    73, Oscar

  • For those of you whom my modification is too complicated and just looking for a "classic" way of using this Twin LNB only as a single LNB with externally fed 25MHz reference via one of the spare F-Connectors, here is a nice page by EA3CNO explaining how this could be done for exatly this same LNB type. (its in Spanish, but you can use Google Translator and/or the photos are rather self explainatory)


    73, Oscar

  • Hello All

    I have 2 Twin LNB's and 1 Single LNB Octagon Green HQ,

    I suppose these are PLL LNB's

    When I listen on beacon, I have small variations in freq ( not drift ), and I think coming from these LNB's, since when I changed to Inverto PLL, it has reduced a lot.

    recieving with SDR Radio, or SDR Uno, with RSP1a, or Pluto, Or HackRF, the Freq wobbulation stays the same

    I have attached a video

    Does anyboy has this phenomenon, with the Octagons..

    Anything to do about it ?

    I suppose it is coming from internal PLL Loop regulation.. so If I would inject 25 Mc with GPSDO, it would be the same, since it is not drift


    • Official Post

    Hello and welcome to the forum!

    Check the forum for 'LNB wobbling', I think yours is a classic example. Other might comment to this but I think this is due to a really cheap/bad crystal. It might go away with external injection but maybe not. Chances are that another LNB will have a better stability so given their low price, just dump this one for a better one and never look back. :)

    73s Achim