Let's build a PA for 2,4 GHz

  • Hi,


    are there alternative sources for the RF amplifiers, other than Digikey and Mouser?

    The DJ0ABR stage 2 amplifier seems to have a lead time of 12 weeks...


    Thanks in advance.


    73, Thorsten

  • Yesterday we did some successful experiments at PI4RCG (RadioClub 't Gooi, Hilversum) with two prototypes of a >50 dB gain 2.4 GHz amplifier designed by one of our members (Rens PA3AXA) to deliver >20W output with 0.1 mW drive, to be used after a Pluto or mixer. See this link.

  • MW7IC2725N, datasheet here. The design is straight forward per datasheet (also F6BVA made a design earlier) albeit that this design is on 1.0mm FR4 PCB (being the height difference between the output tab and GND tab).


    The MMICs were added by Rens AXA per our request because "if he was already busy drawing the PA part, why not add some extra amplification and filtering to use the board after a mixer or Pluto?"

  • DO5MZ No PCB's at the moment. Project is in its early stage. There is already v2 of the PCB on the drawing board. Yesterday the amplifier was connected to a HMC213 mixer and ADF4351 with 1968 MHz LO and 1 mW 432 MHz in gave 25W 2400 MHz out. So that also works.

    I'm now busy with building the 3rd prototype and do some tests, also to test reproducibility.

  • OUT: 21W

    IN: 2W

    24VCC


    Hi Sandro,


    Is that right, please? What's the Idq please? If I know, it is needed around 0,3 to 0,5A idq at least. So there is max. 0,6A of active current as photo shows.


    24V x 0,6A x 50% eff. = 7,2W out


    I am running 28V with Idq 0,5A. The output is modified by idea DK5DN

    and input is my idea - make PCB line (add wire and solder) thick as I can. I am reaching 28V/2,2A in key down. There is 2W input (or less!) from LZ5HP transverter. I dont know the output. No power meter SRI.


  • Hi Viliam.


    I used idq around 0,33 amp.

    My wattimeter have a slow rate measurement and i dont have how accuracy calibrate.

    My tests i used 18 to 32 vdd. To 30 vdd, the current was 1,75 amp.

    Some months ago i quited this project and started other LDMOS.

  • dj0abr

    Can you give some information about the overall current consumption at 24V for stage 1 and stage 2 for 100mW input power?

    There seems to be only a value for stage 1 (about 700mA@24V) but nothing for stage 2.


    Thank you.


    73, Thorsten

  • Hi Thorsten,

    if you drive it with a single carrier up to compression it will draw around 1,5A. When used with an SSB signal usual for QO100 its below 1A.


    DL1ZU , bitte wende dich an dl1ev@gmx.de, er hat einige Platinen vorrätig.


    The BLF2425M9L30U is available at digikey from stock. No.: 1603-1067-ND


    vy 73, Kurt, DJ0ABR

  • Friday is my free day, so time to hobby! As guinea pig #2 built the 'Radioclub 't Gooi' (PI4RCG) MMIC amplifier however, deviated a little from the original design (didn't had all the parts, so the junkbox is always my best friend ; -) and used two TQP3M9009's as driver MMIC's (original design uses two SBB3089z's). My MMICs have more gain and hopefully all will be stable! Amp has to be tested of course.

    Below a pic of WIP (Work In Progress) (click to enlarge)


  • Friday is my free day, so time to hobby! As guinea pig #2 built the 'Radioclub 't Gooi' (PI4RCG) MMIC amplifier however, deviated a little from the original design (didn't had all the parts, so the junkbox is always my best friend ; -) and used two TQP3M9009's as driver MMIC's (original design uses two SBB3089z's). My MMICs have more gain and hopefully all will be stable! Amp has to be tested of course.

    Below a pic of WIP (Work In Progress) (click to enlarge)


    That looks very promising.

    Congrats.

    73 de CT2IRJ
    Sal

    Salomão Fresco

    Callsign: CT2IRJ

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

    QTH: Fazendas de Almeirim, Portugal

  • Friday is my free day, so time to hobby! As guinea pig #2 built the 'Radioclub 't Gooi' (PI4RCG) MMIC amplifier however, deviated a little from the original design (didn't had all the parts, so the junkbox is always my best friend ; -) and used two TQP3M9009's as driver MMIC's (original design uses two SBB3089z's). My MMICs have more gain and hopefully all will be stable! Amp has to be tested of course...

    that looks really good ! Please think of a PTT input to switch off the quiescent current during RX.

  • PA3FYM Are you sure that there is no need for one more filter between second MMIC and final stage to prevent self oscillations ?

    There is too much gain in these two stages (final & driver). From my expirience if I use a directional coupler to observe the output I could not easy see self oscilations at 700 MHz that I have but with a power 30 dB attenuator I can see it clearly.