Posts by dg0opk

    Hi all...

    some work for the next weekend... ?

    ANDREW MW7IC2240 MK2 ...maybe running on 12V for a new portable setup....;)

    BUT NOT TESTET so lets see.... (look update)

    73 de dg0opk

    UPDATE: 1.may 2020


    first test are done, i got the following parameters with 12V DC input and setting the idle current overall to 1.07A@12V
    ( around 550mA @24V)

    Rf-Drive Idc(A) @ 12V Pout effienciency overall (with DC/DC)


    off 1.07

    -3dBm 1.16 26.8dBm low

    2dBm 1.38 31.7dBm 8.8%

    7dBm 2.03 36.5dBm 18%

    10dBm 2.6 38.3dBm 21%

    12dBm 3.48 41dBm 29.7%

    13.5dBm 4.37 42dBm 29.8%

    16.5dBm 5.67 43dBm 29%

    18.8dBm 6.4 43.4dBm 28.5% (SATURATION)

    amp is linear nearly upto max.15W, Pout max =22W @ 24V

    NOTE: you need some additional CAPACITORS because of the DC/DC supply...

    this PROJECT is nearly finshed now....

    73 de Michael dg0opk

    Hallo all...

    some short update...

    got a delivery of the small LM317 modules ... which can be modified with a little work (more than i have thought)

    what to do...

    - remove the trimmer resistor

    - cut out the ground pads on the upper side of pcb

    - make an "island" for the other 2 pins of the trimmer on the lower side of pcb

    - resolder the trimmer

    - add 820R (smd) and 100nF (smd)

    pictures and diagram of the modified pcb attached...

    73 & have fun with modification of amplifiers

    Michael dg0opk

    Hallo all...

    made today some tests with MW7IC2240 module from ebay...

    NOTE: i have no calibrated measequipment here so maybe there can be an absolute power error of 2-3dB... maybe anyone can verify and can post the results.... TNX

    here are my measurements

    2 modules were tested and have nearly identical parameters.

    PSU: 27V , idle current stage 1 was set to 100mA, idle current stage 2 was set to 500mA

    test frequeny 2405MHz, generator is ADALM PLUTO with driver SBB-5089Z + RF2126 , satsagen software

    Pin 0dBm 0.75A Pout=30dBm Gain=30dB DCinput=20W

    Pin 10dBm 1.5A Pout=39.7dBm Gain=29.7dB DCinput=40W Efficiency 22.5%

    Pin 15dBm 2.5A Pout=43.2dBm Gain=28.2dB DCinput=67.5W Efficiency 31,1%

    Pin 18dBm 3.0A Pout= 44dBm Gain= 26dB DCinput=81W Efficiency 30,8%

    Pin 20dBm 3.2A Pout= 44.2dBm Gain= 24.2dB

    the amplifier is very linear until 10-15W, max. Pout is about 25W, gain @ 2405MHz is 30dB,

    the output trimmer was turned nearly out , harmonics are > -50dBc no other modifications were needed

    It looks this is an easy and good useable amp for NB (15W) and a good driver for DATV (max.5W)...

    pictures attached...


    73 de dg0opk

    additional information about from 11april2020:

    like seen in the posts from UA1CCU it is possible to use one bias controller for both stages.

    I tried out my temperature compensated version for MRF7S21110 (look up in this thread) and it is working very nicely and stable over temperature. The idle current change is very low with cold (20deg) and hot heatsink (50deg).

    The Idle current of the module has to bet set to 600mA for best linearity. In DATV maybe 4W with shoulders 40dB are possible. This exactly the datasheet specification for W-CDMA systems.

    73 de Michael dg0opk

    Hallo ...

    an short update

    using a simple and cheap BIAS stabilisation circuit for the MRF7S21110 with good results

    Note: The BIAS CIRCUIT is (c) by dg0opk ... only for private use..... no reselling is allowed ...! (it makes no sense, look info 12.april 2020)

    73 & happy easter time ...

    STAY HEALTY Michael dg0opk

    EDIT and additional information 12.april 2020:

    i found this one as pcb version from china ...which is maybe usable for the bias circuit after a small modification

    73 de Michael dg0opk

    Halo Edson and all others....

    many thanks for your information about the station setup... that is very interesting ....

    But i have no idea about the different decoding levels and the performance of WSJTX also on different days ....normaly the same signals on the transponder must reach the same SNR level if you have enough ground noise of the transponder.

    Maybe there are some other influences in the signal path of the propagation and maybe also in the satellite hardware?

    BTW: an very interesting test ....

    73 for now

    Michael dg0opk

    Hallo ...

    some more have reached the -24dB .... but my receiver (85cm Dish, ADALM PLUTO) shows sometimes better signal levels of some stations ...

    anyone have an idea about the difference in decoding levels... in WSJTX ???

    Maybe it is interesting to hear some ideas about... and maybe it is helpful to get more about the monitoring station for this test...

    which hardware is used?

    Tnx and 73 de dg0opk

    Hallo ...

    first reception test this evening after the change.... cold and clear sky in germany...

    MER 11.6dB D7 @ 120cm OFFSET DISH... (with empty transponder)

    So some more space to play now ... and really good sig of the beacon now... reaching BADR4 Signal level 11.996H

    TNX AMSAT ...

    EDIT: 2nd signal TEST on 85cm TDA88 8.3-8.5dB (TBS6522, EBS Pro 17)

    73 de dg0opk

    Hallo all...

    here my FT8 & FT4 receiving results from yesterday....

    sometimes running PLUTOSDR (FT8) on 85cm in parallel to the AirspMini at 120cm (FT4+FT8)

    setup: TWIN LNB with internal TCXO + SDR Console 3.0.21 with software drift correction + virtual Audio to WSJTX

    73 de dg0opk

    Hallo all...

    here i will upload my RX Data from 21mach 2020 FT8 and FT4 monitoring on my 120cm Offset DISH with

    TWIN LNB (TCXO mod by DG0OPK), AIRSPY Mini, SDR CONSOLE 3.0.21 with BEACON LOCKING for drift correction and virtual audio cable to 2 instances of WSJTX (FT8 and FT4)


    WSJTX frequency is set to 1296.6 MHz for uploading to PSK31reporter ... (but not all spots can be seen because PSK31reporter dont support 3cm until now)

    73 de dg0opk

    Hallo ...

    i will try to let run my rx monitor on FT4 and FT8...

    received spots are sent with 23cm frequency marking (so not all spotted in PSK31reporter

    LINK last 12hours...…band=480000000-1400000000

    Additional NOTE

    some station are marked with unknown frequency in PSK 31 reporter

    so they can not be seen with 23cm filter

    maybe it is time to open PSK31reporter to 3cm (10.368/10.489 MHz)

    73 de dg0opk

    Hallo Robert and Thomas..

    tnx for your response ....

    but note ... we are not using an terrestrical radio path... we are using free space propagation with LOS (line of sight) so it is very interesting to monitor the changes of an LOS path which maybe only depends on some changes in the ionosphere at 10GHz ... ??

    never though and seen before that there are changes in path loss ...

    yes they are changes on heavy rain on bad weather conditions with thunderstorms (rainscatter) but changes on clear sky?

    (this is what i mean as a goal)

    Very interesting to hear someting about

    73 de dg0opk


    got today some more level now... also with snowfall on the QTH....

    9.6dB is reached again on 120cm ...nothing was changed on the setup ....

    maybe the wheather is going good now in DOHA... ?? again

    @ DH2VA

    and maybe we have really some "ionospheric scintillation" depending on the local position of the receivers?

    i dont know... but maybe it is interesting to watch about this...

    73 de dg0opk

    Hallo all...

    after checking my receiving systems this weekend i could detect an loss of MER of the DATV Beacon on 10492.5 ...

    it is about 0.3-0.5dB weaker thank in the weeks and the other times before

    the effect is on all my 3 receiving systems nearly the same but maybe some detuning of strong winds ???

    level with empty tranponder (only beacon seen)

    85cm LNB at Center MER 7.2 (before 7.8dB - sometimes over 8dB)

    85cm LNB 7degrees offset MER 6.5 (before 7.2dB)

    120cm Offset MER 9.3 (before 9.6-9.8dB)

    Can anyone confirm?


    the TV Signals from BADR 4 12168 V ,11996 H are unchanged and reaching 11.5 to 12 dB on my 120cm

    73 de Michael dg0opk