Posts by SV1BDS

    Hi,

    This date is for Greece !!! Maybe for your location there is an other date. I manually look using Orbitron for dates. Maybe there is a more efficient way to look. A usufull link is mooncalc.org that does not need software installation.

    Hi,

    A trial to listen to DL0SHF EME 10 GHz beacon is planned. At 16/10 moon is passing 2.5 degrees away from QO100. A GNURADIO flowgraph is created to receive it via Pluto. Audio is feed to speakers, recorded and to WSJTX at Linux. Any successfull experience?

    Hi,

    Here in my QTH there is a short time tested capability of linking the QO100 station to a VHF/UHF station. This is planned to be used in an emergency. Is JOTA a case that can be used, especially under the COVID19 situation? This is a good case that this capability can be really tested so it will be ready for emergency usage.

    Hi,

    For the ground path the common solution of one ground point (star topology) is used, selecting the power amplifier as this point as it is the highest current device (5A). Thanks HB9SKA for proposal.


    An other puzzle has occurred, the sequencer. The requirements are:

    - controlled voltages : +Tx(5A), +Rx(0.1A), Coaxial relay (0.35A - positive or grounded), +main(2A for PLL Lo)

    - Input lines (control): PTT, Lock alarm( from PLL, can be programmed for active low/high)

    - power input : 12-13.8 V 7A


    Some good sequencers is of W1GHZ link1, link2a ,link2b, link3a, link3b, link4.


    The basic idea is to control also the main power supply from a P-channel mosfet. I use IRF4905as I can found them in eBay. But the main difference form these ideas is that if I put the Tx P-channel mosfet in series with the P-channel main power mosfet a important voltage drop exists. I use two IRF4905 in parallel to have a voltage drop of about 0.4 V for the Tx. So the idea is to put all the P-mosfets (Main, Tx, Rx, Coax relay) directly from +12-13.8 input power line. The problem is that Tx or Rx is activated when Main is Off. I have to redesign the control logic.

    If there are some other proposals than W1GHZ please inform me.

    Hi,

    In order to do proper cabling for 10 GHz transverter for positive and ground cables I have some questions. For positive power a sequencer is usufull to protect coaxial relay from hot switched and PA from SWR during switching (in my case there is no problem as a circulator exists). For ground cabling is more complicated. There are three ground paths. One is the RF path via the semirigids between shielded boxes. The other one is the metal box that the elements are fixed. And finally the power path that provides power. The question is how to properly cabling it. The current of the PA is about 5 A. Any proposals are welcome !!!

    Hi,

    I plan to create transverters for 2.4,5,10 GHz. Do you know any forum or list for technical discussion and schedule QSO ?

    For 5,10 GHz I must take permission from local authorities. QO100 is a perfect back communication channel !!!

    Hi,

    You can test the same frequency range as an analyzer. If you observe the same pattern you receive external or internal signals. If you receive less or nothing is leakage from Tx. The Pluto is not shielded.

    Hi,

    A proposal for the CW beacon is to transmit in 5 or 10 dB attenuation steps in order for someone to evaluate his receiving SNR. Maybe one of the two will be used this way.

    Hi,

    In my opinion when you insert 30 dB you loose SNR. As far I can understand you have a 2 S units at no signal. This is not a real problem that overload your receiver. My proposal to eliminate this you can add a 10 dB attenuator. If you put a bigger one maybe you loose SNR. The real result will be a quiet receiving.