Posts by DL5RDI


    Hello Wolfgang,

    with 100mW a modification of the PA is not mandatory. It will work just out of the box.

    But if you want to tweak every mW you can think about the bridging of the Input RX-TX-switching diode (bringing a few more mW of drive to the transitors). And about bridging the Output switching diode (this improoved my signal via the transponder 1dB).

    73 de Johannes


    Radio amateurs who receive this transmission via QO-100, please send us acknowledgements or talk to DA0Apollo directly via shortwave or the NB transponder on QO-100.

    I would realy like to speak to D0APOLLO and give feedback, but until now I just saw an activation on 20m which is to far for ground wave and to close for sky wave for me. Via QO-100 I did not find them yet. But perhaps tomorrow they consider to give a chance to OMs within 500km (e.g. 40, 80 or 160m) and/or a noticable presence on QO-100 NB transponder ;-)

    I still look forward to work DA0APOLLO ;-)

    73 de Johannes



    reading your post I think you mix a few different things.

    1. The shorting of pin 4-5 wil set the PA in a permanent TX mode. This will not add any mW to the output power. If your drive level is >2dBm this modification is not necesseray and you will not notice any difference.

    2. VK2XAX made 2 modifications. These modifications are only useful if you use the PA not only for TX (like for QO-100) but also for RX (e.g. terrestrial 2way QSOs in 2,3 GHz).

    (Removing the input TX/RX switching and replacing it with two SMA-jacks; one for the TX path and one for the RX path - the output switching is not modified).

    The second modification is also only useful in a 2.3GHz 2way QSO situation. Here he modified the RF-Vox to a "hard" PTT-switch. (This is also not needed in QO-100).

    If you have enough drive level (about 200mW) none of the above modifications give you any advantage.

    The only modification rising the output power in this situation is to bridge the output-switching diode. (and perhaps to add the small wire for a little bit less voltage drop inside the PA).

    73 de Johannes


    do you have a DVB-S receiver? If "YES" you could set it to one of the Astra 2 (28,2°) frequencies (ASTRA 2 should have a big signal in your area and you should see an image even when you are "about" the right direction.

    Having found ASTRA 2 you can use your amateur equipment and turn the dish slightly "clockwise" (towards west) and you should see signals of QO-100.

    With a Satfinder you will find a big signal on 28,2. The signal of ES Hail is "overlapped" by the ASTRA 2 signal thus you will not find ES Hail with the Sat-finder directly. You have to perform the above procedure (finding ASTRA2 and slightly turning towads west).

    Perhaps there was something in my text which helped you just a little bit.

    73 de Johannes


    I use 10MHz and 24MHz.

    (when you have a LNB originally running with 25MHz your output is around 1129.600 - no problem for a SDR - and thus you can also use a normal SAT-TV-Receiver for wide band).

    Thus for me it is a win - win situation. 10 and 24 MHz is a working QRG-combination and as bonus DATV ;-)

    73 de Johannes


    thank you for this nice description.

    I modified a few of these a few month ago. I did not even desolder the F-connector and remove the PCB and I did not desolder the XTAL.

    When the PCB is in place you see the solder lands of the Xtal which are going trough the PCB.

    With a scalpel I cut the solder lands in a way that there was no more contact to the xtal and a rest of the solder-point. On this point I soldered the wire for the REF-frequency. But you can also just cut the traces from the XTAL (see last Image the two big copper Points at the top) and solder the wire like seen in the Image). All other changes were made similar to Oscar's description.

    In this way you do not have to remove the PCB and you do not need to desolder the XTAL.

    73 de Johannes


    I first want to thank Heiner (DD0KP) for the hint to ask Mathias.

    My special thanks goes to Mathias (DD1US) who assisted me by phone in making the right setting in SD console to get the Pluto work also in TX with this superbe software (thanks to Simon !).

    Thank you very much for the help and solving my problem !!

    73 de Johannes

    Just a small "anancastic" remark concerning satellite DXCC via QO-100: :-)

    According to the ARRL DXCC rules the TX and RX must be in the same DXCC.

    This means: All contacts which are made by RXing via a websdr, which is not located in the same DXCC as the TX do not qualify for the DXCC according these rules.

    (e.g when you are listening via Goonhilly WEBSDR and you are not TXing from G the QSOs are not valid for DXCC).

    Like I implied in the beginning I wrote these lines with a big smile on my face. I just thought that this information can be helpful when you are aiming for SAT-DXCC and are talking about your RX-equipment to a rare DX ;-)

    73 and don't take this article to serious


    Hello David,

    Two questions:

    1. has the converter one or two 10GHz inputs (if two one should be marked H and one V or similar)

    2. Has the dual band feed have two outputs for 10GHZ (also one H and one V or similar ?)

    If not both conditions together are fulfilled I "fear" that I am right.....

    But let us wait for some people already using such a setup - and let 's hope that I'm wrong ;-)

    73 de Johannes

    Hello David,

    it's nice that you can switch the converter between NB and WB. But as far as i know the converter can NOT switch the polarity of the antenna. Therefore you must have a 10GHz feed with a vertikal and a horizontal output and the converter need for each a seperate input.

    This is one main reason why I always propagated the LNB (modified or not) solution.

    73 de Johannes

    P.s. If someone knows better than please tell me - I always want to expand my knowledge ;-)

    Problem with TX with SDR Console and ADALM Pluto


    after successfully experimenting with "analog" up- and downlink equipment I started to experiment with the ADALM PLUTO and SDR-Console 3.10.

    The RX-setup is nearly "plug and play" and is running fine.

    But I have problems with the TX. When I switch to TX I can heare a rising of the noiselevel in a receiver next to the Pluto aat 2400MHz, but I can not find a real signal. When I watch the meters (Power, ALC etc) of SDR console they also show "0" which means no signal output. Even when I put the sliders for Gain, Power.... to 100%. I suspected my MIC, but also when I use TONE or TUNE no signal output is shown or can be heard.

    BTW. There is a constant carrier on 2400.117 even when the Pluto is just in RX.

    I use a old Thosiba TECRA Laptop (I have to run SDR Console in "Realtime"in Win 10 to have no drop outs in RX). (The usage of the MIC is allowed in the security settings)

    (In the Pluto I made the software frequency expansion (70MHZ-6GHZ) and activated the 2nd processor core by software - but this should all have no effect on my "problem")

    Perhaps someone can give me a hint what I am doing wrong.

    73 de Johannes

    Hello Stef,

    my setup looks like that from OE9WLJ (POTY much closer to the mounting bracket than in your images) and I have only about 1dB "loss" compared to the LNB in the focus without the POTY. And like PA1EW already said the dielectric lens is not in the right postion.

    73 de Johannes

    I also modified a Starcom SR-3602 wihch was different from all others seen here (only a "nomal" Xtal on the "Backside" of the board).

    I bought and modified it, because the "neck" (after cutting away the "horn") measures 20mm and should fit inside the POTYs cavity.

    I will test this and the resulting performalnce in the next days.

    I already tested a VENTON LNB connected with an olive-clamp to the POTY - the result was very disapointing - tranpondernoise just 2dB with 1,2m offset dish.

    In the moment I have a Megasat DIAVOLO where I drilled a 22mm hole in the platic cap and just fitted it tight on the POTY (ca. 5.5 dB transpondernoise - this is very close to a LNB mounted exactly in the feed point without the POTY).

    Both tests were made with the "original" dielectric lens of the poty.

    I will report my result with the SR 3602 fitted inside the POTY

    73 de Johannes