Posts by DM4DS

    I first have to make a picture from the repaired one.

    The "old" one is no longer in use while the PCB traces burned after more than 35W on DATV....

    I received a different Amp with the "same" problem.

    The problem was quick found . It has nothing do to with the doherty or what ever. There are small 10Ohm R between the 28V and the Bias of each Transistor and they were "burned" . They are not complete dead, they are 50kOhm and so the voltage is wide too low.

    I soldered in new 10Ohms (5 on this one here) and the complete amp is working excelent. Nothing on the doherty was changed!

    Measure them on yours and i hope it´s the same on your side. You can measure them inside the AMP, no need to desolder them . 10Ohm or 50kOhm is a wide range and your Multimeter can this :)

    Have a nice weekend
    Sandor
    DM4DS

    Um nochmal etwas von einem sehr frühen Post aufzugreifen: MegaSAT LNB


    Benutze selbst in einem Setup das MegaSAT Twin bzw. Quad Diavolo ( Diablo ) LNB. Beides sind PLL LNBs und haben in meinen Augen einen tollen Vorteil, wenn man auf externe Referenz "umbauen" möchte.


    Beim MegaSAT LNB sitzt der Quarz direkt mittig zwischen den F Buchsen (bei der Twin Variante). Dadurch ist es sehr leicht möglich, eine F Buchse zu kapern und für externe Speisung zu missbrauchen. F Buchse von der Platine getrennt, kleines C und 1,5cm Kabel zum Quarz, fertig ist die Huckepack Lösung fertig. Platine muss dazu nicht aus dem Gehäuse!


    Der LNB läuft dann entweder auf dem internen Quarz, oder wird ab einem externen Signal von -20dBm "überstimmt" und steht so gut Eure externe Referenz ist.

    Grüßchen

    Sandor

    Are you really paying 4€ per qsl?


    I know , a stupid question but I must ask.


    But what is more interesting for me: if yes, why?

    Update:

    the amp burned all PCB trace behind the combiner after 30 seconds on DATV with ~35W.

    Flo tried to repair it but was not able to do. Now it´s running only on 1 Transistor and running ~35W with very bad efficency.

    I modified myself another one and this one is doing 150W @ 28V @ 16A without any problems.

    Greetings

    Sandor
    DM4DS



    Old Post

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    Today i got the PA from DB8TF - Flo back . Amazing.


    Pictures #225


    First QSO was with Flo and its fantastic. For SSB it´s quick too much power with my 1.2m dish. I think it´s easy to trigger LeiLA , we didn´t!


    In KG-STV super clear Eye-diagram.


    After i figured out how to stream the small ksyms, i´m good for some DATV :)

    Thanks again Flo. Surprise follows!