Posts by DH2VA

    its no so much a matter of asking but a matter of measuring. If properly done, you would have to do it at the feed. Unfortunately, this is 7/16 coax connector there and even then we would require the precise antenna gain.

    But as a guess, 3m is 35dBi and 100mW is 20dBm so we have 55 dBm EIRP, maybe 3dB more.

    A 90cm dish has some 24dBi, so 2W should be equivalent. Which I believe experience has already shown.

    After almost 2 months of operation of the transponders, I would like to make a survey which modes are being used on either transponder. This is especially true for the NB transponder, where I am learning every day about new digimodes! But also for the WB transponder I think it is time to collect data from people what setup they are using. SSB and CW are the well known ones but there are tons of other digimodes being used!


    The goal of all this collection will be a talk for the Hamradio Friedrichshafen in June. It shall serve as a guideline for all newcomers what can be done on the satellite and what setup is required. Certainly, after the talk is complete I will upload it to the webpage as a general information 'leaflet'.


    How can you contribute:

    - send in your mode used and a description of your groundstation, both for uplink and downlink. Pictures are appreciated!

    - give some estimate if you are at the limit of feasability or less power is possible.

    - at minimum, send a waterfall screenshot of your mode. Please no audio files as they get quickly large and don't play well in a presentation

    - give a link to the used software and/or the technical details of the digimode.

    - describe from your own perspective what the pros and the cons of this mode are.


    If used in the talk, all information will be credited to the original source. Please understand, that I will have to make a selection of entries, otherwise the talk could get boring rather easily (not all of the talk should be SSTV or FT8). And I need to stick to some time limit..


    Looking forward to your contributions! You may post directly to this thread or (if you think it's too much) send directly to (mycallsign)@amsat-dl.org


    73s Achim, DH2VA

    Trust us, we would love to share more technical details. But we have only little insight ourself and the little information we have is heavily NDA'ed. But we get two transponders for this price, so I am willing to live with it.:)

    When it comes to phase noise, a good TCXO can be better than a badly designed (or set up) GPSDO. Its advantage is the absolute frequency accuracy, so if you can live without it, I would go with the TCXO solution. Much less of a hassle as there are many errors one can make with GPSDOs.

    Actually David G0MRF did this study many years ago:


    No DX on LEO's ???


    Bottom line: you need some powerful propulsion to get from A to B.


    Now here is the catch: launch providers are more and more unwilling to accept non-paying secondary customers (hamradio) with a high-energy detonation device (propulsion) just next to their multi-million dollar main customer. Both AMSAT-NA and AMSAT-DL (and others!) have tried to overcome these and other problems in the past decades with little success.

    The term here is 'snowflaking' an amplifier (german term: Fähnchenschieben) and I consider it an art (and those who master it 'witches' .. hi!).

    Any amplifier has a complex impedance it wants to see on both input and output to produce max. output power. The striplines on both sides transform the complex port impedance to our known and loved 50 Ohms system impedance.

    Of course, real life is much harder. Matching the input influences the output matching and vice versa.. and matching for max. output is sometimes not identical for matching for max. gain.