What TX amplifier do you plan to use?

  • Hello Thomas, Yes I have seen this. But I am confident, that the pallets are OK. They are removed from some amplifiers and so they are used and without any warranty. I have bought 2,4 GHz PA PCBs advertized as scrap in the past and they all work without problems. Will keep you informed, but delivery is proposed at the end of December.

  • Hello friends,

    This is my first post.


    I'trying to modify a Nokia PA with 2 x BLF8G22LS-160, it works but I don't understand why I have only 18dB of gain.

    I get, with 18dbm of input, 36dBm of output and with 25dBm (max input for SPB2026Z) of input, 43dBm of output.

    If the first chip SPB2026Z was damaged the signal wouldn't be amplified!!

    I saw the datasheet of this chip and this need of 5Vbias on pin 1 and a minimum of 0dBm but I don't understand Vpc but I measure Vpc=2.3V with and without signal.


    I tested the Vg for each ldmos, on the driver I measure Vg=2V, the central final ldmos 2V the other finale 1V.

    Are they correct?


    Is it possible supply bias by external with a zener e trimmer and what resistance should be removed?


    73 de IZ1QXJ

    Antonio

  • info my modification for a 2 x blf7g22l-130 umts for bias increasing voltage from 0.58 to 1.95 Volt .

    1. removed origininal smd 262 Ohm resistor from gate to ground in trace.


    2.added 2x 3800 ohm resistor to capacity on board

    3.voltage increased from factory 0.58v on ldmosfet2 to 1.95 v due to this modification

    4.ldmosfet running in class AB for linearity

    5.power output plus minus 50 w

    6.attached image for proper biasing and how the ldmosfetnr2 becomes active when bias is more than 1.4v and the critical 2.3 volt.

    bias higher than 2.3 volt can destroy ldmosfetnr2 (info)

  • Interesting new amplifier pallets at ebay. Did someone use those allready? I have ordered 3 of them to test.
    https://www.ebay.de/itm/A3T23H…id=p2047675.c100752.m1982

    73
    Gerhard

    Hallo ....


    i ordered also this module in Nov 2020 and got it running, without modifications using a small heatsink with 2 fans.

    Testet the AMP in DATV with upto 75W now... and all looks ok and working stable and is very linear.


    Test on CW PEAK @ 120W out burned an capacitor on the DC Line on the PCB but i could repair it. Transistor survived.


    73 de dg0opk

  • Hallo,
    I have also finshed first tests last week and got about same results. 60W DATV at 30V/10A. Now waiting for a bigger power supply. There is no tuning necessary. About 15 dB of gain at 2406 MHz. Maximum gain is around 2350 MHz, but only 1 -2 dB more. These pallets do have a nice PTT design. There seems to be a temperature switch on the pallet also, but I have not tested it yet. I have used a 4 mm copper plate for heat distribution and a heatsink with blower.
    My pallets seem to be B-ware, but obvisiously have never been used. There are markers on the back pointing maybe to a point with lack of soldering to the copper plate. So far no problem.
    I am now going to construct a PA with two of these pallets to get about 120W DATV out for my small 1,2m dish.
    There was another sale on eBay, but with a pallet for 2500 - 2600 GHz. Also ordered one to see the difference.
    73 de Gerhard OE3GBB

  • Hallo,
    I have also finshed first tests last week and got about same results. 60W DATV at 30V/10A. Now waiting for a bigger power supply. There is no tuning necessary. About 15 dB of gain at 2406 MHz. Maximum gain is around 2350 MHz, but only 1 -2 dB more. These pallets do have a nice PTT design. There seems to be a temperature switch on the pallet also, but I have not tested it yet. I have used a 4 mm copper plate for heat distribution and a heatsink with blower.
    My pallets seem to be B-ware, but obvisiously have never been used. There are markers on the back pointing maybe to a point with lack of soldering to the copper plate. So far no problem.
    I am now going to construct a PA with two of these pallets to get about 120W DATV out for my small 1,2m dish.
    There was another sale on eBay, but with a pallet for 2500 - 2600 GHz. Also ordered one to see the difference.
    73 de Gerhard OE3GBB

    Hallo Gerhard....


    yes a really nice and good information from you.... for the gate current power down there are analogue switches STG719 which maybe can be used for PTT with external logical level... i have not tried until now ...but it looks very interesting . I am using on the AB side about 500-600mA idle current and for the PEAK amp gate is set to 0.7V nearly like the information given in the datasheet.

    Power Out in DATV reaches about 50-60W at 30V @ 8A , a bit more going upto 10A in DATV means about 75W without problem.

    Tested the amp only on short time until 12.5A that gives 100W+ out ...maybe more is possible but maybe out of spec and out of DATV linearity. So i think 75W is the max for our amateur radio use.


    NOTE: The DESIGN looks very narrowband so other version will maybe not work good.


    THANK YOU AGAIN for your information


    73 de dg0opk