Posts by dj0abr

    thanks to everybody for testing the monitor.


    It may be a bit slow because my internet upload speed is at its limits if more than 20 users are using the site,
    but thats good for stability testing :)


    This evening I will try it on a new RPI-4. I don't expect that the RPI is fast enough, but I'll give it a try.

    Hello,


    usually the eshail.batc.org.uk webmonitor is used to see the activity on the QO-100 wideband transponder.


    I needed to see a similar picture, but from my own dish and LNB to compare it with the batc spectrum. And I want to
    stream it into the Ethernet or Internet like batc is doing.


    Using the hardware SDRplay RSPx I have written a web monitor including spectrum and waterfall.
    The software runs under Linux. Since the capture rate is 10MS/s a PC is needed (but I had also some success to run it on an Odroid-N2 SBC).


    Currently I have it running for testing on a desktop PC which is connected to an RSP1A SDR and a 120cm dish with a Megaset LNB.


    It can be view here:

    WB-WEB-MONITOR


    (for easy use, activate to "Autom:" checkbox and set the "average" slider according your preferences).


    After some testing and debugging I will publish it via Github during the next week for general use.


    vy 73
    Kurt, DJ0ABR

    ok thanks, that makes sense. So if I choose 1/4 than only one quarter is used for video. This is why my TX buffer is filled up to 99%.

    It also explains why 9/10 gives the best results in my local transmission over only 5m distance,

    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.

    thank you for answering my questions,

    Heiner, a test with 2000 kS/s worked fine too,


    For 333 kS/s:
    G0MJW: that did the trick. I reduced the input resolution to 640x480 and the picture was fine.


    An additional improvement was to change the FEC to 9/10.
    Can anybody explain what this FEC setting is doing ?

    With 1/2 I still have some blocks, with 9/10 the picture is clean.

    With some other FEC settings (i.e. 1/4) the TXbuffer fills up to 99%.

    I am trying to get a DVBS2 TX running with Pluto.
    In general it works, but the video quality is very bad.


    PC: Win7, Intel i7 16-cores, 16GB ram

    Pluto: all hacks installed, second core activated
    Pluto connected via USB or ETH (makes no difference)

    Software: DATV express, 333 S/s

    Cam: 1920x1080p webcam


    Receiver: SF8008

    RX signal strength: 99%


    When I receive videos (333 S/s) via QO100 from other people using pluto, all looks fine, nice quality.


    When I directly (not via QO100) receive my own signal, generated by pluto, there are strong artifacts and blocks. These blocks are "pumping" every second, the picture gets very bad and then improves a bit during the next second. When objects in the video are moving, I see only blocks and extreme artifacts like the tail of a comet.


    Please can anyone post the settings of the datv-express menus, or has another idea what I could try to improve quality ?


    73, Kurt, DJ0ABR

    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

    today we built the full PA equipped with all boards,


    the board in the middle is the (already released) 10W-PA. Right of it is the prototype 30W booster and at the left is a small universal board with an attenuator to fit the input to the 50mW of the Amsat TX mixer.


    All boards can simply be screwed to a cooler, but we did an aluminium box, just for fun. The red plug is the 24V supply (2A max) and the black plug is the PTT input.


    The 10W-PA followed by the booster has these data:


    Output: 26 watts Peak

    Input: 10mW (for full output, nice to be used with an SDR)

    Gain: 34 dB

    Efficiency: 48%


    in my case I have put an 10dB attenuator in front of the PA, so I need 100mW for full output.

    This small board (in the picture on the left) has pads for up to 5 SMD components (0603 or 0805). It can be used as attenuator, filter or whatever is needed.


    The RF lines of all boards are at the same position, so all boards can be easly stacked together with a solder bridge. Alternatively SMA connectors can be soldered to each board's input and output.


    I have ordered a couple of these filter boards and also the booster, should arrive end of this week, as usual you may contact Ernst (dl1ev@gmx.de) if you need empty boards.


    Best 73
    Kurt, DJ0ABR

    it took some time to get the new PCBs, but they arrived this week.


    The first board which is finally released is the 10W amplifier.


    10W means, compression begins at 10W output. In SSB we can expect an average power of 2,5 watts and if a speech compressor is used up to 4 watts, which works well with many QO-100 antennas. Gain is 17 dBm. We built a couple of board and no additional tuning was required, all worked immediately, so you usually don't need any measurement equipment except a DC voltage/current meter.


    The board has a PTT circuit now. The quiescent current is only ON during TX. The requirements for a cooler are very low (in SSB only), a piece of aluminium or any other cooler is usually sufficient.


    The complete development documents are available for everybody for free. Please see here: www.dj0abr.de .

    A member of our local club, Ernst, dl1ev@gmx.de, has empty boards available. If you want to get a board, please write an email to Ernst and ask for board number: 10821.


    The next step is a 30 watt booster which can be connected between the 10W PA and the antenna. The prototype is already working, currently I wait for the final boards.


    vy 73
    Kurt, DJ0ABR

    Before doing the final layout, we started some experiments with the BLF2425M9. Mounted on a homebrew prototype PCB this Mosfet generated 22 watts out from 500mW input with almost 50% efficiency.

    (nice for use in portable 60cm dishes).


    The plan for the final PCB is now as follows:

    1) 2.4 GHz SAW filter at the input (as recommended for the Amsat TX board)

    2) MHT1008 amplifier

    3) LP filter

    4) --- CUT ---

    5) Attenuator

    6) BLF2425M9 amplifier

    7) LP filter


    at step 4) there are simply a couple of holes in the PCB, the PCB can be cut here into 2 parts. So if only the MHT1008 is needed, the PCB is broken at 4) and the other part is thrown away (the PCB is very cheap :) ).

    If one needs both stages (i.e. for higher gain), then he uses the complete board with a gain of up to 34 dB.


    Some applcations (i.e. the Amsat Mixer board) need a gain of >17 but less then 34 dB. To adjust the gain to the needed value a simple attenuator (0,5 watts SMD resistors) can be mounted.


    This week we are doing the measurements with the BLF2425M9 board and also design the low pass filters.


    vy 73
    Kurt, DJ0ABR