What TX amplifier do you plan to use?

  • G3XOU Thanks for the Bias Cirquit.


    DM5RM Good hints from your side.


    I received my Nokia Amp from Bisonelectronics and startet to rework the input/output (attached directly semi-rigid Cable with SMA-Connector instead of the very specific existing ones). Biases I will leave as it is for the moment and ordered this Supply to have enough power:

    https://www.ebay.de/itm/1PC-Po…ksid=p2057872.m2749.l2649



    Roland, could you help me with the following two questions, please:

    1. Did you change the Doherty Cirquit of the peak amp like Flo?

    2. Could you upload a photo of the copper piece on the C?



    73 de

    Alex, DK4FT

  • DK4FT

    Here is the picture of my one and only mod so far. The size resp. area of the selfadhesive copper foil depends a bit on the operating voltage.

    You should start with a tiny piece of foil and then gradually increase the area until it doesn't get any better.

    And don't forget the cover...



    Just by the way, with your power supply, you should almost be able to weld ;-)


    73+55 de

    Roland, DM5RM

  • Just tested the Amp with my Lab Power Supply.


    Did

    - the Doherty Change to enable peak FET permanently,

    - change input sockets to SMA

    - change Output

    - remove Isolator/Circulator at the output,

    nothing else, so far.


    IDQ is 3,2 A @28V.

    The Amp has abt. 48dB Gain on 2,4 GHz, not too bad.

    If the meassured gain is correct, there is no need for snowflaking...


    Due to my Lab Supply I am able to produce only 2,5 W at the moment, but the Amp is getting really hot with both End FETs enabled even in idle. (need a fan...)


    Now I am wating for the big supply (welding Source ;-) )


    Thanks Roland for the picture....

    Here is my one....

  • So,

    at 60 watts of DATV signal, the connectors are very hot .... at both ends. PA and Wattmeter ...
    Maybe a bad quality of plugs?

    Or wrong way to work with SMA plugs ...



    73s de Robert

  • Is appreciated.

    It´s a 50 Watt slug. (2400-2500 MHz)

    I get at 1,5 watts input power 50 watts output power. My driver is only 1.75 watts.
    With 1.75 Watt the pointer of the Wattmeter goes to right "stop". Should be estimated then 60 watts .. (by 15,3 dB gain)

  • Update: Received the Power Supply for the Nokia Amp and killed the FETs?!?


    After first connection the Idle Current dropped from 3,2A to 1,7.

    I doublechecked this with the lab supply, which confirmed this.

    At the second try it dropped to few milli Amps :-(


    It seems the supply fried my FETs, as Voltages on the FETs are still fine...


    I check polarity and voltage = all fine.

    With the Oszi I checked for Transients, there were some on top of the DC, but only abt. 20mV.

    So I have no Idea why the supply killed the Amp, but it happened.


    Any Idea what went wrong?

    I seem to miss some detail at the moment :-(

  • Hi colleagues,


    Thank you very much for nice job in here. I baught also one PA from Poland. Base on your test I have turnd on my board... not so bad, but... look on the picture below:


    Due to this: .



    I did like this:


    And how it look at the oustide:


    Dismantled cirulator place is perfect to install N socket. Two holes exeactly on correct position, for another two you have to modify holes on the socket - Dremel machine is the best. Now I have typical N socket, much better than this oryginal non typical one. On the cover you have to drill 20mm hole with 25mm distance on stright line from screw - very easy to do it.

    What hapened with trace? Who knows in details, but in one moment I saw 15A from 27V PS and next some sparks, that's it. Maybe my modification of outlet socket was not proper. Now is haevy duty :).

    For now only circulator was remowed, installed combiner (bigger) and bias setting as recomended. The rest oryginal without any snowflacking up to now. I use Dx Patrol - only 100mW output. Due to this is better to use preamp also. On the inlet is 3dB att, i have added SMA att 2+5+6 dB for tests. Step by step I have removed one by one... current increased and finaly without external att I have whistled harder to the microfone.. and you see efect. But as DB8TF wrote: they are really solid and all transistors survived. Now during test "only" less than 10A.

    Unfortunately I havent now any measurement equipment for 2,4 and I use only DC measurement with Dummy load. With 12m of RF7 and 8m of H155 I saw my signal on sattelite a bit lower than CW beacon. I know, that cables are not for this aplication, but I used what I have connected to my shack. First test done.

    I don't need high power, but PA will not be very close to the antena, than I need few wats more to cover losess on the cable and additionalk few wats because I plan to use smal wi-fi grid antena.


    73 Henryk

  • Alex, please verify bias voltage. My first test with lab PA and 24V, on the right transistor was close to 3A, but for short time and I never see it any more. On left 20mA and similair situation. Now I added external bias voltage and all is ok.


    73 Henryk

  • tnx to all...


    I always connect input and load before adding the power supply.


    I received some hints to follow up and will do as soon my time permits.

    First one received more than once is to change to manual Bias Voltage instead of the build in automatic one...


    Keep you informed....

  • Hi

    Hides http://www.hides.com.tw offers on its ebay platform https://www.ebay.com/itm/2-4G-…416003:g:lIkAAOSwo0BdWsIL a small power amplifier that is suitable for portable operation or mounting directly to the antenna, especially for ADALM-Pluto or other 13cm transmitter with low output power.

    I got two pieces to test, here's the pictures and result :


    Both Amplifier sweeped.....




    Maximal output power between 1,7W and 1,9W on 2400MHz & ~37dB Gain.

    Vcc: 8 Volt.......16 Volt ( not so critical because a voltage controller is on pcb board )

    Icc: ~800mA & full output power


    Schematic diagram here: MMZ25333B-DB-01-V02_180226.pdf


    Amplifier Chip data here: https://www.mouser.at/datasheet/2/302/MMZ25332B4-1517182.pdf


    Monitor voltage you can get from here:

    Example for ADALM-Pluto use....

  • NOKIA AMP MODIFICATIONS FOR DATV AND REPAIRS TO BIAS SUPPLIES

    Hi All,


    Like some others I had intermittent problems with the Bias supplies for the PA and Driver with Iq varying wildly . The faulty parts were quickly located using Freezer spray.

    In each case the Driver IC supply decoupling capacitor was intermittently breaking down. In addition the 150ohm resistor which feeds the bias decoupling capacitor from the +28v supply on the PA Bias was intermittently varying in resistance. I've removed the SMT part and replaced it with a standard 150 ohm resistor. I carried out the "snowflake" modification on the output of the pre-driver as Roland, DM5RM modification and added a "snowflake" to the PA Driver output.


    Results :

    Vs=28v

    Iq=1.9A

    Freq: 2405MHz

    RF input: +9dBm

    RF Output: +48.2dBm (P1dB)

    Gain: 39.2dB

    Ic = 8.2A


    Reducing power to +45dBm, Ic = 6.3A


    Interesting Video of a tear-down of a NOKIA Base Station including this PA module at:


    http://kaizerpowerelectronics.…n-power-amplifier-part-4/

    Some photos follow showing Modifications and bias regulator repairs.


    73, Dave G3XOU