2,4GHz transmission check

  • Hello all,

    what equipment do you use to check the SSB mod on the 2,4GHz uplink signal?

    First i considered to buy an expensive receiver which works with SSB up to 3GHz but then i bought an "Arabsat Low Noise Downconverter" to use with a cheap RTL-SDR. So long its working ok, clearly there is some drift but to check the mod its enough.

    What do you (plan to) use ?

    vy73 DB8TF

  • I have a local WebSDR on 2320 MHz which I used to check my SG LAB transverter set to this frequency.

    When Es'hail-2 is opened I can change it to 2400 with a jumper setting.

    By the time I build this thing in an extra enclosure (with a PA of suitable size, to be determined after opening of the transponder) I will probably make that controllable with an external switch so I can use the same thing for 13cm DX when desired.

  • I will have an extra SDR (USRP2 w/SBX board) available. I will either listen to my uplink signal locally over the air, or use a Hybrid Coupler (and if needed attenuator) and feed it into the RX2 port of the SBX. [I am planning on being able to combine multiple uplink signals for various experiments/reasons]

    TX/RX port on this particular SBX will be an Aux uplink (possibly FT8), while the existing N200 w/SBX will have Primary narrowband uplink and downlink.

    The USRP2 and N200 will be phase locked via a MIMO cable, thus enabling ranging and timing experiments



  • DB8TF: The N200 was purchased a number of years ago when the exchange rate was far far kinder to us here in the UK [We won't talk about all the reasons it isn't now...], the USRP2 turned up second hand, as did the extra SBX, at a very good price, so I grabbed both of them as soon as I could, realising that there was great potential for experimentation with Es'hail-2/P4A :)

  • Ah yes I of course have my G0MRF converter for P3d... didn't even think of that!

    But I only tested on 2320.2 until now so that is not so practical for now.

    Of course once we are on 2400 it can be used...

  • Hope you understand a question from a "newOne".

    Is it important to check the own transmission signal using own "stuff"?

    I think i can read the quality of my tx-sigs listening on the RX signal coming from the satellite.

    mni tnx for your information


    -most of the time qrv in CW-

  • DL5RDI: exactly what i mean...

    I want to be sure that my signal is clean before i transmit over EH2

    vy73 DB8TF

    A very good and respectable motivation for sure, but if we are honest 99% of all hamradio operators don't do this. Going full duplex as suggested for satellite operations is very helpful here but the round trip time is messing with the brain. It needs a bit of practice to cope with a delayed version of own voice.

  • We will (hopefully soon) see how different HAMs use different methods to get good and clean signals over the bird. It will be a lot of fun for sure ;)

    Back to the "Arabsat Low Noise Downconverter"...

    I found a picture on my phone of a measurement from that converter: on 1,25GHz (3650-2400) it has about 12db less gain than in the "normally" used frequency range.

    But for simple equipment checks it's ok.

    I don't know if this is very interesting but maybe it helps some OMs who are considering to buy such a converter.

    vy73 DB8TF