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Thread: 2x BLF578 >2KW amplifier

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  1. #1

    Default 2x BLF578 >2KW amplifier

    I ran the amplifier (1.8 to 50MHz), it has two LDMOS transistors BLF578, more info on

  2. #2
    Join Date
    Feb 2004
    Bakersfield, CA


    That's an interesting article. The BLF578 still cost over $300.00 so two of them can be expensive. On the other hand tubes are not getting cheaper. It would be good to see the IMD performance as well as mismatched performance. The data sheet says the BLF578 is good to 13:1 SWR and not be damaged. This was in a pulsed condition. CW would be a totally different value. At the cost of them I would not want to be the one testing for that. The solid state devices are becoming more available and are attractive for linear amplifier service. It's just a matter of time and every amateur will think fondly of the days when you had to tune the amplifier and change bands with a switch. Sigh....
    Have fun

  3. #3


    I created that board for Robert SP5G
    it is a very powerfull board
    I have since then moded the amp and made many changes to it.
    Baruch 4z4rb

  4. #4


    not really, because the amplifier is not prepared by a colleague working as it should, the one about which I write is a completely different design in terms of components and solutions.

  5. #5
    Join Date
    Nov 2005


    Hello Guys!
    I hope that my friend Baruch will change the vendor of components also, because I have already said to him that I have a lot of doubts about the real functionality of the RF components used, in fact the "smoke" put out from the capacitors (with 1/10 of the power) is not the normality into the output circuit and I hope again that is not a symptom of the other big issue, because he said me that is the first one problem that occurs with these boards.
    Anyway I stop here my comment because I am waiting from Baruch of a new set of capacitors and after we will see.
    73 franco
    73 de IZ2HFG Franco

  6. #6
    Join Date
    Nov 2005


    Hi man, I'm waiting the your decision.

    - Resend me the two complete boards with mounted devices but absolutly and fully tested with the your report by
    frequency/power out/minutes or seconds of the test with max power out and so on.

    - Obtain the refund of the money that I have spent and I will send back your boards, the two copper bases and all destroyed devices.

    Sincerely and with all my good will I see no other possibility and there are not alternatives, to go out of this situation, honestly and with high head for you.

    As already wrote, let me know your final decision
    Last edited by IZ2HFG; 11-01-2012 at 09:51 AM.
    73 de IZ2HFG Franco

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