What TX amplifier do you plan to use?

  • Yes, like Achim said , that delivers the most spectral pure impact. With these multi carrier signals it's not anymore 'adjust bias for max output' (like with single carriers in the old days ; -)

  • Quote

    For mrf21045, my bias voltage is 2.7-3.0, 0.55-0.9a at 24v, and 42DB is output when 30DB is input

    So you have 12dB gain? 42dBm out for 30dBm input.

    I wonder if 50W output is possible, perhaps the internal matching is not so good at 2400. (28V and 14.7dB gain at 2200MHz on datasheet)


    David

  • Hi great, I see you use the Daiwa power meter but the power returned 2.4ghz?

    Roberto

  • iw5bsf: the power meter is a usual "Daiwa NS-660P" cross-needle power/swr meter. This goes to max 150Mhz.


    But i use a external (and very rare!) measuring head "Daiwa U-66S2" which works from 1,2 to 2,5GHz with 1,5/15/150W power ranges.


    73s DB8TF

  • 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

    --------------------------------------

    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!

  • Hi DB8TF,


    Great work!


    Could you please share what are the changes you have done to the board?

    I own the same PA unit, however I’m trying to figure out what changes need to be done.

    I see that you have replaced the input connector with SMA (BTW, what is the original connector?)

    And that the circulator was replaced with a N-type. There are few copper patches (I assume for better matching). What changes are not so obvious? Is the amplifier still working as a Doherty one?


    thanks


    Yoram