Posts by dm4im

    Guten Morgen.

    Die Tatsache dass die Eloxal-Schicht weg ist, bedeutet nicht gleichzeitig, dass der Massekontakt besser geworden ist. Was, wenn beim Einlöten des Transistors nicht genügend Lötzinn in die Löcher geflossen ist? Oder auf der anderen Seite wieder hinaus, sodass jetzt nur eine kleine Fläche auf dem Gehäuse aufliegt?

    73, Martin

    Well, a whole bunch of mods to make a unit usable that is sold as "plug 'n play" , right? Add RTL-Stick & Laptop, add PTT, put RX-Splitter inside, add USB..

    Ok, this is my last post in this thread. Again i "lean out of the window too far" as we say here. Will stop now and adjust to the overall mindset: Who cares...

    No flames, just my 2 cents:

    A few remarks about the duplex, yes the unit is not duplex, so what.

    It violates the rules set up by Amsat when used as advertised, that's what. No mention of simplex in their advertise, why? Do they know things the buyer shouldn't? If i was a clueless buyer, i'd feel betrayed pretty soon. And by watching the signals on qo-100 one may sense that not all, but some, dx-patrol users are clueless. That's why they listen to the promises by D-P and believe inconsistent statements.

    if i turn on 70cm and hear a station in downlink, I know i am on the correct uplink.

    Well, that is what the vast majority of users does . They link their receiver to their transmitter. I've been listening since early 2019, it got a LOT better over time. Only few user don't.


    Your observations all relate to operator skills.

    How come you have a full-duplex setup, when there is nothing wrong with the simplex setup?

    I stick out my neck a lot farther than i should, but couldn't hold me back. It sure will turn out i should have. Oh my.. :/

    73, Martin


    i just found a new DX-Patrol toy on their website, they call it QO-100 Groundstation. Other than again there is no way to toggle RX/TX by a wire or switch , the manual says some things like how easy it is to use and the like. I heard someone on QO-100 say he is using the DX-Patrol QO-100 groundstation and he can NOT receive while transmitting. :/ There is no reference in half- or full-duplex in the manual. Anyone have info?

    73, Martin


    no matter what lnb you use, they ALL will drift, even when modified with a better oscillator. Maybe some really expensive ones won't drift. If you want only small drift, do not replace the built in oscillator by a better built in oscillator. Instead, feed the reference via coax from a place with minimum temperature changes, preferably from your shack. 25MHz multiplied by 390 is tricky to stabilize. A slamming door can cause frequency changes. I had a gps controled 25MHz vctcxo in a box and even this drifted a small amount for a moment caused by the moving air when i opened the shack door , then quickly settled again. A ocxo may do the trick. The one i used was cheap , not very accurate, but rock stable, meaning i had an offset of about 1.5kHz on 10GHz, but virtually no drift. Currently i use a gps controled vcocxo , everything is fine. So you see, there are different levels of accuracy and stability. You should start with a normal lnb and let sdr console take care of the drift. Once you are using the satellite you will quickly learn what level of stability/accuracy will suit your needs.

    73, Martin

    Edit: If you go for a (vc)tcxo, please be aware: Some of them change their frequency in steps. Some kind of "digital" hops. You don't want that. Others change their frequency smoothly. That is what you want.


    Amsat modifies the Opticum LTP 04H , so this one is known to work. This is one i use in my portable setup, you may find them in the uk as well:….html?&trstct=pol_3&nbc=1

    This is the one i currently use in my fixed setup….html?&trstct=pol_6&nbc=1 ; one output modified for reference input, one output terminated, 2 outputs for nb and wb transponder. They will work w/o modification. sdr-console takes care of the drift.

    73, Martin

    Edit: Amazon UK has them : Goobay 67272 Universal Quad LNB , Goobay 67269 Universal Single LNB

    Gosh, they are expensive in the UK!

    Maybe the LNB uses some other multiplication factor, not 25MHz*390=9750. But anyway, once you found the signals from QO-100 around 874MHz, you can calculate your downconverter offset. 10489.8-874.4 =9615.4 . Now setup your transverter definition in sdr console using 9615.4 - not 9750 - and you are good to go. I beleive the 400kHz after the decimal point is the inaccuracy of the internal crystal, so the offset is either 9615 or 9616 . But i also might be totally wrong. The fact that both lnbs show signals at 874.4 may lead to the conclusion that this really is directly fed into the sdr , not via the lnb. 437,075*2=874,15 .

    73, martin

    Exactly, you should receive a carrier on 10489.8 -9750 = 739.8MHz .

    If you already set up sdr-software like sdr-console or similar, you should see a needle coming out of the noise around that frequency.

    This ensures you that your lnb is working.

    73, Martin


    You can try receive the 24th harmonic of 437.075 =10489.8 ( 739.8 if the crystal is 25MHz , or 1105,8 if 24MHz)

    Just transmit with your handheld in front of the lnb. Remember any frequency error from your handheld will be multiplied by 24. So you may have to search a bit for the signal depending on the overall accuracy.

    73, Martin

    Well, i can tell that i hear level 24 , even 27, but only that it is there, just a bit over the noise. If i was meant to understand level 24, i would fail. So I voted 21.

    So to really determine how deep you can hear in the noise, random words do the trick. Or maybe a string of 5 figures in cw, like the old ZRO test on AO-10. 73, martin


    there is a chapter in the sdr-console manual titled PTT.

    A quick but not deep read brings me to the idea that one might connect a (foot)switch - via USB or serial - for keying sdr-console.

    Now if you also hook a RX/TX relay system to the (foot)switch you might have all you need. In other words: PTT for sdr console AND for whatever hardware is provided by a mechanical switch.

    73, Martin


    please keep in mind, that C:\\ProgramFiles\VideoLAN\VLC means the vlc executable must be in the folder named VLC.

    In other words: C:\\ProgramFiles\VideoLAN\VLC is NOT the executable.

    Or even in other words: C:\\ProgramFiles\VideoLAN\VLC\vlc.exe is the complete path to the executable.

    Is that the case on your win10? Also, try to install vlc.exe in the path that is represented by the translation to italian language (if that is the set language) , maybe that helps.

    73, Martin

    Hello Armin,

    you can use this board, click! : SI5351

    There are examples in the net, saying to cut a trace and use output 2 as the input. I recommend not to do this. If you need 2 frequencies, the calculation program might advice you to use output 0 and 2, not output 0 and 1.

    Remove the 25MHz TCXO and feed 10MHz via a capacitor.

    Download the SiLabs Clock Builder Software . Cheat the clock builder software by telling it you are using the SI5351 with 8 outputs and reference input.

    You will need a clean power source and you might need low pass filters at the outputs. I tested it with 24 or 25 MHz output plus 116MHz for my transverter, it works.

    73, Martin