Posts by DD1US

  • SWR POTY verbessern

    Herko,
    I am afraid that your design does not produce proper circular polarization.

    The correct phase shift needed for CP is right between the two dips, i.e. in your plot at 2350 MHz.

    IMHO you tuned your feed 50MHz too low.

    Kind regards

    Matthias

    http://www.dd1us.de

  • DATV Beacon changes

    Hi Adrian,

    when the bandplan and WB display get updated our friends from BATC/AMSAT-UK will also check and if needed adapt the overpower indicator. it may take a couple of days as people there are busy ... please be patient, thank you.


    Kind regards


    Matthias


    http://www.dd1us.de

  • How do I resubscribe to AMSAT-DL ?

    Hi Dave,


    maybe there are more people who want to join and support AMSAT-DL, therefore here some more instructions.


    After you have selected the one-year membership for 120 Euro (see above) you go to "Warenkorb".


    There you should see the following screen:



    Then you click at "weiter zur Kasse" and should then get to this screen:



    Once you have entered your personal data like address then scroll down and you should see:



    Please note that you will have to pay using paypal. I hope that is conveniant for you.


    Here you click at "Jetzt kaufen" and you ordered the membership.


    You will get to Paypal to finish the payment.


    Please let me know whether it worked or if there are any more questions.


    I will be happy to help you.


    Kind regards


    Matthias


    http://www.dd1us.de

  • How do I resubscribe to AMSAT-DL ?

    Hi Dave,


    you can simply order your membership for 2020 through the AMSAT-DL shop.


    The text is in german but maybe one of the online translation tools might help you.


    If not I can guide you through.


    You start here: AMSAT-DL Shop


    There you click on:



    Then you go to "Warenkorb" and follow the checkout procedure.


    Thank you very much for your continuous support of AMSAT-DL. This is very important to us.


    Kind regards


    Matthias


    http://www.dd1us.de

  • Question on using a MHL-21336 small chip amp.

    Hi Adrian,
    I also got some fake chips. The correct MHL-21336 is powered at both Vdd pins with 28V.
    At the fake chips Vdd1 is the gate bias with lower voltage, Vdd2 is the drain bias with 28V.
    The drain current will rise steeply when exceeding the gate bias voltage of 7V.
    The fake chips most likely contain modules of the type MHPA18010N, MHPA19010N or MHPA21010.

    They are 10W modules for cellular networks in the range 1800, 1900, 2100 MHz.

    I have not tried retuning them as I think it is not worth given the low price of the original MHL-21336.

    I can confirm that the modules from the vendor given by DC2TH are the real ones.
    Other vendors in China are selling the fake units.

    I will update my description shortly.

    DC2TH, is it ok to use your posted pcitures in my description ?

    Kind regards

    Matthias

    http://www.dd1us.de

  • MY QO100 SETUP

    Hi George,

    yes corner adapters can be a real problem. Some years ago I learned this the hard way when tuning a 23cm helix antenna array ... it turned out the problem was such an adapter. On 13cm it will be even worse / more likely.

    Kind regards

    Matthias

    http://www.dd1us.de

  • MY QO100 SETUP

    George,


    if you use the lime USB you already have multiple antenna ports for the different bands. However the lime USB only covers up to 3.6 GHz wihout the LMX8001 frequency extensio. If you add the extension you can go up to 10 GHz / 3cm band.


    Kind regards


    Matthias


    http://www.dd1us.de

  • Remote-Betrieb über QO-100

    Hi Mike,


    Peter may chime in but I am sure it was meant, that the station has to be operated at your home, whether it is rented or belongs to you ... I am not sure how to express it properly in English, maybe you registered home ?


    Kind regards


    Matthias


    http://www.dd1us.de

  • NB Transponder Bandplan and Operating Guidelines

    Dear all,


    Geri, I assume you need to increase the bandwidth in your receiver and center the CW beacon: then you should have a steady receive level, mark and space have the same downlink level.


    The received levels from lower (CW) beacon and the (upper) experimental beacon, which transmits presently also CW, are here at my station identical (plus/minus a few tenth of dB).


    So presently both (CW) beacons can be used as level reference.


    I do not recomment to use the PSK beacon level as especially SDR console does only measure CW signal levels precisely.


    Kind regards


    Matthias


    http://www.dd1us.de



    Thus both, the lower (CW) beacon and the exper

  • Bandpass filter

    I agree with the statements above but would like to recommend to add some thoughts:


    if your filter has significant insertion loss and/or limited power capabilities it is better to place it before the final PA.


    Assume you are operating a 200W PA at 50W to keep it very linear for DATV and your filter has an insertion loss of 1dB
    then you probably do not want those additional losses attenuating your precious power ...


    Kind regards


    Matthias


    http://www.dd1us.de