Inverto SN411-OOPRO-OPN PLL LNB PCB picture

  • Hello all,
    Today I have opened a 3$ DTH TV LNB. Some detail if anyone needed.

    DTH Provider: AKASH DTH (Bangladesh)
    LNB Make: Inverto
    Model: SN411-OOPRO-OPN
    XTAL: 25.00MHz

    Here are the PCB and shell photo. The Xtal looks so small and delicate, I don't think I can remove it without hurting the PCB.

    Thanks,
    73, S21RC

  • Hello.

    Just melt enough solder on it to make it really hot. It will swim on the solder at some point. Then use pliers to pick it up and remove it.

    73, Martin

    Thanks Martin, I have hot air soldering station - but there are so many parts nearby I might melt those as well :p

    Sure will try to remove it and put an external 25MHz reference - maybe I will be successful after few try (good that they are not expensive).

    Thanks, 73, fazlay

  • With a good soldering iron you can apply a big blob of solder on the surface of the crystal and continue heating it up until it comes off. This probably will destroy the crystal. Remove the solder with a solder sucker / vakuum pump when done.

    73, Martin

  • With a good soldering iron you can apply a big blob of solder on the surface of the crystal and continue heating it up until it comes off.

    And do so with the PCB out of the casing (mind the antenna pins - ESD sensitive!)

    If you try this with the PCB still in the case you will find that the casing cools enough that the solder won't melt.

    This PCB material is a pretty good heat conductor.


    And keep in mind that leaded solder has a lower melting point. So you can "wet" the pads with old solder to mix old with new to reduce the melting temperature.

  • And do so with the PCB out of the casing (mind the antenna pins - ESD sensitive!)

    If you try this with the PCB still in the case you will find that the casing cools enough that the solder won't melt.

    This PCB material is a pretty good heat conductor.


    And keep in mind that leaded solder has a lower melting point. So you can "wet" the pads with old solder to mix old with new to reduce the melting temperature.

    Thanks, I am waiting for the 25Mhz TCXO to arrive from PRC. Once I get those I will try to replace the stock Xtal. In the meanwhile a bullseye LNB arrived which I ordered last month. Will put the BullsEye to see how much improves.

    ** Antenna installed, already can receive the QO-100 using a 60cm TV dish with unmodified LNB.

    Thanks,
    73, S21RC

  • Hi,

    you might consider feeding the 25MHz over the coax to the lnb, preferably from your shack. A tcxo built in the lnb will drift with temperature changes. Thus it is smart to have the tcxo in a place with minor temp changes. Furthermore, this leaves room for later improvement, like making the tcxo adjustable or feeding an odd frequency derived from the tcxo.

    73, Martin

  • Hi,

    you might consider feeding the 25MHz over the coax to the lnb, preferably from your shack. A tcxo built in the lnb will drift with temperature changes. Thus it is smart to have the tcxo in a place with minor temp changes. Furthermore, this leaves room for later improvement, like making the tcxo adjustable or feeding an odd frequency derived from the tcxo.

    73, Martin

    Thanks Martin, haven't thought about the drift due to external temperature changes.

    Here is the rough list I have in mind:

    1. RX with ordinary LNB while waiting for TCXO [Done]
    2. TX antenna [in progress]
    3. 10MHz reference for RX/TX SDR from OCXO 10MHz [in progress]
    4. Doing TX test [waiting for SDR to arrive]
    5. Improving stability - making a GPSDO with OCXO

    6. Making a 25MHz clock from the GPSDO/OCXO using si5351 and a bandpass filter.

    Any advise is always welcome and appreciated.

    Thanks, 73, S21RC

  • Hi Fazlay,

    5. Improving stability - making a GPSDO with OCXO

    Here is a link how to do it. It is in german, but i'm sure there are projects in english language to be found.

    Simple GPSDO by DL4ZAO and DL7UKM

    A gps receiver provides a precise 1kHz/10kHz/ or 100kHz clock . The 10MHz from the ocxo is divided by factor 10000/1000/ or 100 to one of these frequencies . A comparator circuit provides a control voltage for the ocxo to adjust it's frequency.. When clock and divided frequency match, the control voltage is right and the OCXO is spot on frequency.

    The Arduino is there to tell the gps-receiver what clock is needed and takes care of the display (time, locator, whatever).


    6. Making a 25MHz clock from the GPSDO/OCXO using si5351 and a bandpass filter.

    Done that. It works.

    73, Martin