Posts by dm4im


    20-25dB over the noise is good. How strong is the upper beacon?

    I see different levels when i compare gqrx and sdr-console, both getting their data from the same sdr dongle on a server running rtl_tcp. In gqrx, the lower beacon is 30-35dB over noise (when tx-ing the steady carrier) , the upper beacon 27dB. In sdr-console, the lower beacon is only 15dB , the upper beacon 25dB over noise.

    Maybe it depends on the settings. Experiment with LNA-Gain etc. Compare weak signals with web-sdrs to evaluate your setup. I can read many weak signals better on my own setup than on .

    73, Martin

    Here's what i get now:


    I tried LNB -> 20mKoax -> Amsat RX-Mixer -> FT-290R2. The s-meter was pinned in the right corner and i mainly heard noise, only the strongest signals were readable. Much better with 20db-ish attenuation.

    Tried a different radio with better strong signal handling. No attenuation necessary. So it depends on your radio. If your radio has it, the ATTENUATOR is your friend.

    73, Martin

    I bought the Universal RX Mixer and assembled it/put it in an enclosure while at my /p location during an easter vacation. I would have liked to find a feed through capacitor in the kit. If you - like many here - are not well equipped with parts, you need to order one . Reichelt doesn't have them, Pollin does. So why not include one in the kit and therefore raise the price to -say- 179.00€ ?

    I sure would have paid that extra 50Cent. It saves an order.

    73, Martin


    Will use the raspberry image for portable operation from my vacation qth, and , most important, for a presentation at DL0WH to show how easy it is to get qrv. We have a bunch of raspberry enthusiasts there, but they somehow lost connection to "radio" in "amateur radio". Just now and for preparing the presentation, i receive the sat on your raspberry image with a 60cm dish behind a closed balcony door and with a tree in the path. Amazing

    But also will try to get it up and running on a desktop pc. Will report here. I'm an even worse programmer ;-)


    I'm running GQRX at home on a Desktop PC. Do you intend to make the source code available so every one can install this on their desktop PC, not only for the raspberry?

    Hi there,

    i tried to inflate with 2 different programs with GUI on a linux computer, both failed. Inflating on the commandline resulted in a file >5Gb. I copied it to the card anyway using dd , but it wouldn't boot. Downloaded it to my laptop and tried there successfully. It also resulted in a file >5Gb, but dd copied it and it would boot. Something is wrong with the file, i should say.

    Anyway, good job! Been trying to run my own installation on a 3b+ over the last few days and failed (audio device underruns) or had a huge cpu-load >78%. So your optimizations, if any , do the trick. Load only abt. 40%. Keep on!


    Today DJ8LC and me measured the re-built antenna according to .The match was a lot better and closer to the desired frequency. I didn't fix the patch to the reflector but only glued 2 spacers on the patch so i could rotate the patch while measuring. The place of the spacers have a great impact on the match. We rotated the patch until we got a return loss about 20dB on 2400Mhz. Then we placed the antenna in it's final box and measured again. 26dB.... Done!

    The antenna is placed in the lid of the box, the box presses the antenna down to the lid when screwed on. Now i need to seal the hole where the n-socket protrudes the lid. see some pictures and a HowTo

    Now desperately waiting for the transverter from LZ-Land. 73, Martin

    Thanks Remco.

    Is this proven? My first antenna was according to the dimensions K3TZ gave, but was well below 2.4 Ghz, at least 800Mhz. Maybe i made a mistake somewhere.

    Is the diameter of the reflector critical? The design by 7N... says 100mm, K3TZ says 4inch (101,6mm).

    Hi there,

    i am new to frequencies like these , coming from the other end of the ham radio spectrum , DC for most people here .

    I greatly failed with my first attempt to build an antenna not made of wire at least 40m long, hi. I built the patch feed antenna, probably with the wrong dimensions. My question is: Can i use the dimensions given by G0MJW in this thread and not drill a 22mm hole ( won't need it) . Instead, i would use a screw and nut in the center for adjusting the distance between reflector and patch. Can i do that? Will the dimensions be the same? Thanks.

    73, Martin