Posts by pe1chl

    Sorry for the confusion.. we planned this for quite some time and got this now arranged with the satellite operator.

    The mailbox message transmitted by the beacon was changed this week (yesterday, I think):

    L HI de Qatar-OSCAR 100 (DL50AMSAT)

    Transponder is open for general use since 2019-02-14.

    Enjoy the Narrow Band (NB) and Wide Band (WB transponders.

    Follow the guidelines and keep transmiter power below beacon.


    For more information visit: http://amsat-dl.org/

    QO-100 was brought to you by Es'hailSat, QARS and AMSAT-DL.

    Good Luck and Good DX via the first geostationary P4-A satellite


    Maybe changes like this could be communicated there? Or is it difficult to quickly change the message?

    Hey I can use it to check the alignment of my yagi! Let's get out the solar eclipse glasses....


    Edit: ok this conjunction was within .6 degrees here so well within the beamwidth of my 80cm dish but I did not notice anything on the NB transponder receive.

    Maybe when I make a plot of the noise floor over an hour interval.


    I checked the alignment standing behind the antenna with solar eclipse glasses and it looks OK (see the silhouette of the mast over the sun but yagi not visible).

    Maybe you can use a coaxial relay and a dummy load, where the relay is energized when the transmitter is keyed? Or you could connect the other port to your antenna and use the relay to switch between local QSO and LNB reception, the relay would be energized only on receive via the LNB (using a switch and a circuit to connect it to the TX line).

    Interesting! I remember when I started receiving satellite TV that there were also events when the satellite passed through the earth shadow (during the night, of course) and the transponders were switched off.

    I have not heard about that recently so apparently there is enough battery capacity now to keep operating.

    S59MZ are you sure the oscillator stops working when you inject the external 25 MHz signal?

    Check if you maybe see 2 copies of the beacon, one at correct (GPS-stabilized) frequency and the other at the (drifting) crystal frequency.

    It could explain your 3dB drop as you may be receiving everything twice.

    An isolator is a circulator with a 50hm termination on one of the ports.

    It sends the signal from amplifier to antenna, but the reflected energy from the antenna (and other incoming signals) is sent to the termination resistor instead of to the amplifier.

    This protects the amplifier from bad SWR, but usually it is done to prevent intermodulation in the amplifier when strong local signals are present.

    Yes of course 75 ohm is OK for this too, I have done that in the past to have circular polarization with a crossed yagi.

    My planned experiment is to have two circular polarized antennas alongside the LNB and see if that results in proper pointing.

    Indeed I also want to avoid shadowing. For QO-100 NB it may not be important (I can afford to lose some signal) but I use the same antenna for TV.

    Ok I understand!

    I am planning to try with 2 circular patch antennas alongside the LNB so I need a 1:2 splitter which I want to do that way but of course the impedance of the match will be 35 ohms so it will have to be done a bit differently.

    Nice to see that your antenna works, maybe I will try that one as well.

    DL5RDI FPV (First Person View) is not the same as WLAN. It is the downlinking of video from drones which can e.g. be used while flying the drone. Of course in theory one could use WLAN and digital video for that, but it induces a delay which would make the drone difficult to control. So in this field of use, analog video with FM modulation is still often used. And of course, an amplifier for that does not need linearity. So you should always be careful not to buy FPV equipment when you want it to use for purposes where linearity is required.


    W.r.t. the reverse-SMA connectors I am less pessimistic. Usually you need a short pigtail between e.g. a module box and an N connector on the outside housing, and you can order the correct type (from reverse-SMA to normal N) and use it without any adapter. This can also be semirigid.

    But of course it is often easy to change the connectors anyway.

    Well you could try to use digital modes like PSK31 and CW and use them with decoding software like Fldigi.

    Then you can make QSO with standard phrases and/or translate what you receive using cut/paste to a translation site.

    But usually with such digital modes you can make QSO just with the pre-programmed function keys that send your name and station details.


    Welcome on the satellite!

    pe1chl You kill a lot of dealers when ordering in china direct. all these products are smuggeld into EU without any tax. no certificate of compliance, no ROHS, no return

    Well, it is not really smuggling. We can receive packages up to 22 euro in value without paying tax, above that we have to pay VAT and import duties, plus a 13 euro handling fee. So it is only attractive to order things < 22 euro and > ~50 euro.

    Frankly I do not care about ROHS, it is for careless consumers only. I do not dump my electronic waste into the environment, and like most amateurs I have more than enough stock of non-ROHS-compliant electronics (and solder) to make this little LNB insignificant. When it is discarded it of course goes to a recycling depot and the lead will not end up in the environment.

    Other compliance may be a factor, e.g. unwanted signal radiation.


    However, that is not my main concern. What I worry about is how it is possible to make and ship things so incredibly cheap. It likely involves non-environmental-friendly production, underpaid workers, people running their business but barely making sufficient income to live and eat, shipping things through systems that are only possible due to unjust exceptions (airlines paying no tax on fuel or fares, packages delivered for free in destination countries according to ancient reciprocal agreement) etc.

    It isn't (cannot be) a fair and sustainable system.


    And indeed, in the meantime it affects our local shops and dealers. They operate on a completely different regime. They have to charge VAT, and they cannot ship anything without charging at least 10 euro for shipping&handling realistically due to much higher shipping and wages here.

    Maybe it is easier for you because you are from China as well...

    I normally get no response when mailing far-East companies with enquiries about products or request for datasheets in English language. (at different companies)


    However this is an interesting part. I still have a Dream Multimedia DM-8000 which has plugin slots for extra tuners. I could try to get such a tuner work in that box, would be much more convenient that viewing through a PC.