Posts by 9m2cqc

    not ANY TX power... only up to its directivity if inserted the correct way around. I would guess maybe 20dB (?) in reverse direction. If you add another 20dB as plain attenuator (which a LNB with its huge gain might easily compensate) you have 40dB of protection for the LNB again accidental TX.

    Great and thank you for the pointers. I will look into this alternative too.

    73, Sion, 9M2CQC

    Thanks for the reply. The thing is I need full duplex operation, so the relay should only be energised (N.O. to dummy load) when the accidental transmission into 432 MHz band takes place. When transmitting on 144 MHz (the upconverter's IF), the relay should not be energised (still in N.C.) so that I can continue listening from the LNB.

    And yes, this can be done with a transceiver like the FT-847 that has PTT lines for individual bands. Unfortunately the IC-910 only have one PTT line irrespective of bands and therefore cant work with this solution. Guess I will just swap transceivers to mitigate this problem :)

    Thank you for all the hints once again :)

    73, Sion, 9M2CQC

    Well, the power protector is not supposed to and neither is it designed to handle long accidental transmission into the LNB path. Its there just to prevent accidental brief key ups from damaging the LNB just like how it was used to protect the SSB UEK-3000 receive only converter during the AO-40 days.

    The whole idea of using the IC-910 transceiver is that I can receive on the main band (top portion, on 432 MHz) while transmitting on the sub band (bottom portion, on 144 MHz into a upconverter) in satellite mode that allows automatic tracking of the uplink and downlink frequencies across the transponder.

    Yes, I have looked into the idea of a pull-up tx-inhibit too but it does not seem to help because I still need to transmit on the sub band while receiving on the main band. However, I need some extra measure in case the top and bottom band is accidentally swapped, thus causing me to accidentally transmit into the LNB.

    Thank you very much for the reply and hope that the above explanation clarifies my original question.

    Hi All,

    Does anyone know sources where I can purchase the SSB RF Power Protector (, or are there any alternative products to this?

    Reason for this is to protect the LNB against accidental transmission especially those with IF frequency of 432 MHz when used with a standard amateur transceiver such as the IC-910H that is capable of transmitting at 432 MHz.

    I have tried searching around but unfortunately cant find anyone who carries this. It was a famous protector back in the AO-40 days and connected inline between the UEK-3000 LNC and a 144 MHz IF transceiver to protect the UEK-3000 against accidental TX.

    Any pointers would be greatly appreciated. Thank you.

    73, Sion, 9M2CQC

    Hi Peter,

    Wow that is a really interesting history and story behind QO-100 !!! And its really please to regain contact again with so many old friends due to QO-100.

    Please do let us know when you are next in Penang and if time permits we would of course like to meet up with you. My e-mail address is good at and my cellphone number is +6012-2299798.

    Once again, I would like to thank you and the team who took so much effort and personal time to make QO-100 become a reality. You guys must have had a really hectic and busy time doing the commission of QO-100 and the GS there, so please do get enough rest and once I get the uplink portion done, will look forward to have a QSO with you on QO-100 :)

    73, Sion, 9M2CQC

    Hi Peter,

    Thank you for the welcome and confirmation that the promo video is still running.

    I am using the Kuhne LNC 10 so that brings 10.4925 GHz - 9.360 GHz (LO) to 1.1325 GHz. Understand that not all set top box can enter a downlink frequency of 10.4925 GHz so what I am doing is to maintain the LO at the box set to 10 GHz and set the downlink frequency to 11.1325 GHz (basically fooling the set top box as it does not allow 0 GHz IF and direct entry of 1.1325 GHz as the downlink frequency. hi hi!)

    I am receiving the NB transponder very FB but in the coming week when time permits I will try to re-adjust the dish again to attempt RX of the WB transponder. As well as get the TX uplink setup too.

    Thank you once again for all your efforts in making QO-100 become a reality and for confirming that the DATV is running continuously on the WB transponder.

    p/s. I believe you know David, 9M2DT a long time satellite operator who has not been active in the recent years. I did mention to him about you & QO-100 and he is eager to try get active again and work QO-100 too :)

    73, Sion, 9M2CQC

    Dear All,

    Sorry for opening a new thread, if this subject was discussed before but I tried to look around but couldn't find any answers.

    I would like to know if (1) the promo DATV video is still running at the moment, and if it is (2) what is the actual frequency and symbol rate (I read its some 2msps?). Also please advice if this can be received via a standard DVB-S2 set top box? Or do I need the MiniTiouner receiver? Alternatively, would the use of F6DZP software with the TT S2-1600 PCI card work?

    Thank you in advance for helping with my DATV RX setup, and looking forward to some QSOs soon once I get the 2.4 GHz TX portion setup.

    73, Sion, 9M2CQC

    Just establish what is the center frequency coresponding for the center frequency of IF (in your case 1129), then modify that into the line of config file that says shown_center_freq=

    Originaly the value is “center_freq” so you need to write 10489.xxxx instead of that.

    Thank you so much for that information, and yes I have got this fixed now :) My mistake as I was looking through the config file but really missed out this line.

    73, Sion, 9M2CQC

    Congratulations for the whole team! Nice waterfall plots on my OpenWebRX



    Hi Zoltan,

    Pardon me asking, but how do you get OpenWebRX to display the frequency in 10489.xx GHz? Would you mind sharing the part of your config file that sets this? I have been trying to do the same but failed.

    It would be so much nicer to show 10489.xx GHz instead of the IF frequency 1129 MHz. Many thanks for your assistance.

    73, Sion, 9M2CQC

    I am using 1m offset dish with Kuhne MKU 10 LNB and managed to get very good copy from QO-100 yesterday. More test and fine alignment of the dish to continue today. Location is in OJ03 about 20km from Kuala Lumpur, West Malaysia.

    73, Sion, 9M2CQC