Can I just ask about a PA from Bisonelectronics.

  • I've just tried out my PA but results are disappointing so far, only just over 20 watts (28V, 3.5A) with about 3 watts drive from a MHL21336 chip. This is being driven by a Lime Mini DATV signal which feeds into a SPF5189Z. Originally I had a 6dB attenuator between the SPF5189Z and the MHL21336 but I have now reduced this to about 3.7dB.

    I have made the modifications to the PA board as described in the notes from Heiner and used 5mm copper tape as mentioned in previous posts. This seems to work well and is easy to do.


    The PA board is identical to the ones shown in the notes but came from another supplier on eBay. I also have two of the ones from Bison which I'm keeping "in reserve" while I learn from playing with the single board.


    The notes mention that more output power can be obtained by not using the input and output isolators on the PA board. Does anyone know how much loss these components may have at 2.4GHz?

    The input circuit on the board has two components to be removed. One is an isolator (labelled X2) but I do not know what the ceramic component near it is - any suggestions please?


    73 Barry, G8AGN

  • I will not get my power supply until probably late next week, depends on the slow boat from China. So unfortunately I can not give any comparisons, but I would also struggle to give definitive readings as I have no accurate power meter at 2.4 GHz all i could do is a comparative level from say two watts with the spectrum analyzer.


    Adrian

  • I've just browsed his ebay page and all of the items for sale are not available...

    73 de CT2IRJ

    Salomão Fresco

    Callsign: CT2IRJ

    GRID Locator: IM59re -- CQ Zone 14 / ITU Zone 37

    QTH: Fazendas de Almeirim, Portugal

  • In the manual it is written that you can improve from 40W to arround 50W by obmitting the input and output isolators. This is written on page 5 and the pictures are on page 6. 20W is written is the performance without changes to the PA. Maybe you should try to measure your result on an unmodified one, to get a good comparison of your changes.

  • In the manual it is written that you can improve from 40W to arround 50W by obmitting the input and output isolators. This is written on page 5 and the pictures are on page 6. 20W is written is the performance without changes to the PA. Maybe you should try to measure your result on an unmodified one, to get a good comparison of your changes.

    That sounds like a really foolish thing to do. The isolators are there for a reason. Don't remove them unless they don't work. Re-tune or replace them perhaps if possible, or compensate for the miss-match.


    Mike

  • G0MJW Mike when I have the time over this weekend, I will post what is the power without the modification and with.. But I agree also I will leave the isolators. maybe I will put two PAs in parallel.

  • In the manual it is written that you can improve from 40W to arround 50W by obmitting the input and output isolators. This is written on page 5 and the pictures are on page 6. 20W is written is the performance without changes to the PA. Maybe you should try to measure your result on an unmodified one, to get a good comparison of your changes.

    Hi Heiner, where find manual ?

    Thank-You

    73

    François F1BPT

  • Heiner


    I've have just checked out one of the "new and unused ?" unmodified Bison PA boards, as you suggested.

    The test setup - see photo - is a Portsdown RPi3 giving a H265 QPSK S2 signal 125kS/s which drives a Lime SDR Mini. This then drives a SPF5189Z board from eBay and then a homebrew MHL21336 amplifier which gives just over 3W at 2.4GHz. This is then fed directly into the PA board.

    The measurement setup is a 40dB coupler terminated by a Bird 50W coaxial load. Power is measured using a HP437B power meter.

    Results were:

    Lime Mini gain = 95, output = 12.2dBW = 16.6W

    Lime Mini gain = 100, output = 12.7dBW = 18.6W

    The output will be slightly higher because of the loss in the cable between the PA and the coupler.

    These figures compare very well with those quoted in the modification notes you sent me earlier.

    73

    Barry