Posts by OE3GBB

    Hello Laurent,

    this one seems to be the smaller brother of my 2,6 GHz board. Expect about 100 - 120 W in DATV when using a combiner of the two stages. Maybe the filters and the isolators have to be removed. The 3 dB Xinger should be oK for 2,4 GHz. The I2C controll maybe the same. Lets see what benno is finding out in this regard.

    73 Gerhard

    Correct, 27*100 is the maximum operation fequency. So the original use at 2620 - 2690 was correct.
    I have seen that it is easier to use those transistors at lower frequnecy than to exceed the maximum frequency.
    Therefore I like the 27 types for 13 cm.

    73

    Hi Benno,

    great to see that others also are working on this pallet.
    For me it is also a side project, at the moment just making a first concept.
    No, it is definitly a 2,6 GHz amplifier, from isolator and also transistors. But that is fine as those Doherty amplifiers seem to operate without change on the HF tracks also on 2,4 GHz.

    The Polisch vendor sold 7 of those, so maybe someone else will join us.

    73 Gerhard

    Hello,

    just received this new type of pallet from Poland. Is someone allready working on it? I am planning to operate both amplifiers together into a combiner. I allready have good results with a similar 2,6 GHz transistor pallet at 100W DATV. So I expect to get a combined linear power of about 160 W DATV out of this new pallet.
    My first analysis is, that there might be a problem with the output isolator. It is designed for 2620 - 2690 MHz. Has anyone measured the actual usable bandwith? The second isolator between driver and PA does have a bypass route, so no problem to cure. The 3dB couplers are from 2,3 to 2,7 GHz.

    The question is, if I have to desolder the big isolators to use the coax plugs, or just leave it, or just solder an output line to the combiner just behind the SWR measurement.

    73 Gerhard

    Can you explain what exactly you want to do?

    A friend asked me to think about an additional repeater at OE3XNK on 23 cm. I did some research on the net how to use SDR for that purpose and found QRadioLink. Have not tested it so far as it seems to be quite complicated for setup. There is also one information on the net how to use a simple script within the Pluto itself to copy a signal from RX to TX. For me GNU-Radio possibly seems to be the best solution.
    It should be at least a standard FM Repeater within the 23 cm band. But I think it this works the frequency could be changed easily to other bands or to crossband. I think there will be no need to decode the FM on RX and modulate on TX. Therefore maybe a linear repeater would be best.
    73 Gerhard

    Hi Gerhard OE3GBB,

    In practice what is important is the degradation in performance. I have to use as much power as I can. I use the WB transponder in the 1st section. I have noticed that degradation exists when others use the WB transponder. I continusly change flowgraphs experimenting. I must try USB modulation as it will permit me to hear the difference and not just degradate the FreeDV performance that I have now.

    QO100 opened a wonderful window of experimtation in high frequencies and digital communications!!!

    All right! I just wanted to get a feeling, how strong the WB signal has to be to stay within an acceptibal degradiaton for mode 1600 (BER 5%?). The WB transponder will reduce the SNR by 2 dB if it is fully populated. So if you normaly need SNR 5 it will go down to SNR 3! From shortwave I think to remember that in mode 1600 we need at least SNR 7 for a decent BER. Mode 700D would be good at lower BER, but I think the modulation should be DPSK, same as mode 2020 over satellite.

    Hi George,

    This is off topic, but you are very experienced in GNU-Radio:
    Do you know of a ready to use model in GNU-Radio for testing a simple RX/TX repeater using a Pluto or LimeSDR? Could be NBFM or linear.

    Want to try 23cm or above.

    73 Gerhard

    Danke für die Info. Ich muss ohnehin noch einen weiteren Fehler suchen, denn die PA hat bei einer Fehlersuche kurz geschwungen und dann stimmten die Gate-Spannungen nicht mehr. Eventuell ist einer der Transistoren kaputt.

    73 Gerhard

    On the terminal connection I get contiuously ....aUaUaU.... with some background sound on the speaker. It is very hard to tune the RX to the correct position. It seems that the transmitted audio is repeated somehow.