Posts by G8KWX

  • BaMaTech DuoBand-Feed: receive poor?

    After all the comments here. - Thanks all.- I did some experiments today.


    Best S:N on the NB beacon I achieve with normal TV lnb and my 80 cm offset dish is 38 dB which is pretty good. Focus is about 30 cm so I have a f/d of 0.4.


    With my Bamatech duo feed, if I very carefully search for and optimise the position of the feed into the focus, I can now achieve 34 dB S:N. .No dielectric lens yet.


    It seems that the position is very critical and not where my standard sat TV bracket had it. I am now going to fabricate a more optimal bracket for the duo feed.


    If I can get a dielectric lens maybe I can get a few more dB to come closer to single lnb receiver.


    All very interesting and why we do this experimental hobby.

  • BaMaTech DuoBand-Feed: receive poor?

    Thanks DJ7WL  DL9SEC,


    Interesting you got 8db better performance by doing crystal lock. I have been using the new feature in SDR Console which allows you to lock the sdr to the beacon, gives good results on all my lnbs. At least for stability. I had assumed that I do not need to do any tcxo mods. Do you agree or is there something else limiting the sensitivity. The phase noise must be really terrible of it hits the sensitivity that much.


    Another thought, has anyone tried mounting a second lnb next to the Bamatech duofeed to get good rx link. Then just use the Baratech for the uplink.


    If that does not work it looks like 2 dishes will be needed 🙄

  • BaMaTech DuoBand-Feed: receive poor?

    Thanks Thorsten, all,


    I see your point about the optimum focus.


    On taking apart two LNBs that work well, the difference to the LSP-02G seems to be the wave guide has a wider aperture about 55mm stepping down to about 20mm presumably a match or somehow related to offset feed point that the 'good' LNB's are designed for. (Pic attached) .


    I now assume that the LSP-02G is meant for center fed dish ?


    Anybody share any light on this.

  • BaMaTech DuoBand-Feed: receive poor?

    HI all,

    Hope you can help me solve a problem. I am using a 80 cm offset dish in south of UK.


    With a standard satellite LNB (Visbleware VK4L) I can receive very well, for example the NB beacon shows 38 dB S:N using SDR Console.


    When I use the Bamatech dual feed antenna, my RX side only achieves 28 dB on receive. (All SDR setting remaining same).

    I have experimented moving the focal point +/ a few centimeters seems to make a few dB difference.

    (My up-link seems to work ok - getting S6 reports with 2 Watts).


    I attach photos. Wondering do I need a dielectric lens for the dual feed LNB because I am using offset dish ?

    Or maybe I have a bad LNB from Bamatech?


    Thanks in anticipation.